Book of Abstracts - Royal Meteorological Society

Transcription

HIGH IMPACT
WEATHER AND
CLIMATE
CONFERENCE
BOOK OF ABSTRACTS
Poster Presentations
Observing Posters
Abstract Board Number 1 – 50
Predicting Posters
Responding Posters
Chamber measurements of emissions and subsequent
processes of light-duty diesel exhaust
M Rami Alfarra, Research Fellow and NCAS Scientist, NCAS
University of Manchester
Poster Board Number 1
Airborne particulate matter (PM) is recognised as a major public health concern, and road
traffic contributes significantly to the PM loading, particularly in populated areas. More than a
third of light-duty vehicles in the UK are run on diesel, and these represent a dominant
source of PM and NOx, with implications for air quality in cities. Furthermore, the black
carbon (BC) content of diesel exhaust may play a significant role in anthropogenic climate
forcing. From the perspective of both climate and air quality, there is a clear need for a
greater understanding of diesel particulate matter, and the processes it undergoes following
emission. For the COM-PART (Combustion Particles in the Atmosphere: Properties,
Transformations, Fate & Impacts) project, we have coupled the exhaust of a light-duty diesel
engine dynamometer rig (VW 1.9L SDI; representative of the EURO 4 standard) to the
Manchester Photochemical Aerosol Chamber. The chamber consists of an 18 m3 teflon bag,
a bank halogen bulbs and a pair of filtered xenon arc lamps to simulate solar light, and
chemical scrubbers to provide clean, filtered air. Particulate and gas phase components
were comprehensively studied using an array of state-of-the-science instruments to
investigate their microphysical, optical and chemical properties. The use of atmospheric
instruments on diluted, rather than direct, exhaust allows for direct comparison with ambient
measurements. In a series of experiments over several campaigns, samples of exhaust from
the diesel engine were injected into the chamber and diluted into clean air. This was done for
different engine conditions (engine speed and load), dilution ratios, exhaust treatment (i.e.
the presence of an oxidising catalytic converter), fuels (standard and bio-diesel), and
exposure to light. Here we present findings of Com-Part and discuss trends in particle
concentrations and properties as a function of engine conditions and photochemical aging in
the chamber.
What do we know about tornadoes in Europe?
Bogdan Antonescu, Research Associate, Centre for Atmospheric
Science, The University of Manchester
Other Authors: David Schultz
Our current understanding of the climatology of tornadoes in Europe is based on collections
of historical events, cases studies and regional climatologies, all of which are limited by the
inconsistencies in reporting practices and observational networks across Europe. Recently,
this situation began to change with more tornadoes reported in the last decade compared to
the previous period and with reports now coming from the majority of European countries,
which allow us to build more accurate and complete climatologies of European tornadoes.
What do we know about tornadoes in Europe? There are two main answers to this question.
First, there is not a widespread recognition of the threat of tornadoes to Europe and, as a
result, few European meteorological services forecast tornadoes. This laack of recognition
results in an underestimate of the tornado threat to Europe. Second, understanding the
influence of climate change on severe convective storms and their associated phenomena
(e.g., tornadoes) remains a great challenge. When considering this influence of a future
warmer climate, the starting point is to consider the observational data. Unfortunately, there
is a lack of long organized and centralized tornado records. Although the first collections of
tornado records were published during the first half of the 19th Century, no system was in
place until very recently to collect tornado reports at a European scale (i.e., the European
Severe Weather Database). Thus, without knowing what is the spatial and temporal
distribution of tornadoes in the current climate, all the analyses of the influence of climate
change on tornadoes are premature. For these reasons we present a synthesis of tornado
observations for 30 European countries between 1800 and 2014, based mainly on regional
tornado-occurrence datasets and articles published in peer-reviewed journals, with the aim
of producing a pan-European climatology. Thus, 9549 tornadoes were included in the
synthesis with the majority of the reports coming from northern, western and southern
Europe, and to a lesser extent from eastern Europe where tornado databases were
developed after the 1990s.
The annual average number of tornado reports increased from 8 tornadoes yr-1 between
1800–1850 to 242 tornadoes yr-1 between 2000–2014. The tornado season has a maximum
in June–August for the majority of the European countries analysed, and in August–
November over southern Europe. The intensity distribution for the 5187 tornado reports for
which an estimate of the F scale was possible shows that the majority of tornado reports,
74.7% of all tornado reports, were for weak tornadoes (F0 or F1), 24.5% for strong
tornadoes (F2 or F3) and 0.8% for violent tornadoes (F4 and F5).
To better understand the threat associated with European tornadoes, the synthesis of the
tornado observations for the 30 European countries was integrated into the European
Severe Weather Database (ESWD). The ESWD is a unique database maintained by the
European Severe Storm Laboratory. An objective analysis of the tornado threat in Europe is
performed using data from the ESWD between 1800 and 2014. Observational uncertainties
associated with tornadoes in Europe exist because only a few European countries have
systematically collected tornado reports and also because of the inhomogeneous population
distribution. To assess the tornado threat to Europe, a Bayesian hierarchical model was
used to correct for the population bias on tornado reporting. The tornado vulnerability in
Europe was also analysed by considering the vulnerability as a function of tornado incidence
and societal exposure. The societal exposure was determined based on the population and
property exposure for European administrative divisions. The tornado vulnerability was then
assessed by considering separately the tornado incidence and societal exposure.
Identifying historic streamflow droughts using
standardised indicators
Lucy Barker, Drought Monitoring Scientist, Centre for Ecology &
Hydrology
Other Authors: Jamie Hannaford, Simon Parry
The complex nature of drought makes it difficult to define and identify. Large numbers of
drought indicators have been developed to identify and quantify drought events.
Standardised drought indicators such as the Standardised Precipitation index and
Standardised Streamflow Index can be calculated for user-defined accumulation periods and
are comparable across both space and time. Here we use the Standardised Streamflow
Index (SSI) to identify streamflow drought events in 15 catchments with long observed
records. The duration and severity of each identified drought event was calculated. Events
were then ranked by duration and severity. Identified droughts showed strong spatial
coherence in drought occurrence and both event duration and severity, as did the most
severe droughts in each catchment.
The most severe droughts identified here using a consistent, objective method were
compared to major droughts identified in the literature using a relatively subjective method.
The most severe drought events identified by the two methods were comparable, although
some events were not identified by both methods due to a range of factors including: data
availability, the choice of drought characteristic and the choice of drought indicator.
However, the method used here illustrates how drought standardised drought indicators like
the SSI can be used to identify and compare drought events over both space and time. The
results also emphasise the need for longer streamflow records so the severity and duration
of historic droughts can be compared to those in the observed record.
Clustering of Regional-Scale Extreme Precipitation Events
in Southern Switzerland
Yannick Barton, PhD Student, University of Bern
Other Authors: Clement Chevalier, Paraskevi Giannakaki, Olivia Martius, Stephen
Pfahl, Hardald Von Waldow
Temporal clustering of extreme precipitation events on subseasonal time scales is of crucial
importance for the formation of large-scale flood events. Here, the temporal clustering of
regional-scale extreme precipitation events in southern Switzerland is studied. These
precipitation events are relevant for the flooding of lakes in southern Switzerland and
northern Italy. This research determines whether temporal clustering is present and then
identifies the dynamics that are responsible for the clustering. An observation-based gridded
precipitation dataset of Swiss daily rainfall sums and ECMWF reanalysis AU1 datasets are
used. Also used is a modified version of Ripley’s K function, which determines the average
number of extreme events in a time period, to characterize temporal clustering on
subseasonal time scales and to determine the statistical significance of the clustering.
Significant clustering of regional-scale precipitation extremes is found on subseasonal time
scales during the fall season. Four high-impact clustering episodes are then selected and
the dynamics responsible for the clustering are examined. During the four clustering
episodes, all heavy precipitation events were associated with an upperlevel breaking Rossby
wave over western Europe and in most cases strong diabatic processes upstream over the
Atlantic played a role in the amplification of these breaking waves. Atmospheric blocking
downstream over eastern Europe supported this wave breaking during two of the clustering
episodes. During one of the clustering periods, several extratropical transitions of tropical
cyclones in the Atlantic contributed to the formation of high-amplitude ridges over the Atlantic
basin and downstream wave breaking. During another event, blocking over Alaska assisted
the phase locking of the Rossby waves downstream over the Atlantic.
Apportionment of Elevated PM10 Values around a UK
Steelworks
David Beddows, NCAS Researcher, The University of Birmingham
Other Authors: Roy Harrison
Hayes and Chatterton (2009) analysed PM10 data from Port Talbot and suggested that
exceedences of the 24-hour PM10 Limit Value (50 µg m-3) may be caused by a range of
sources and conditions. It was concluded that the main sources contributing to elevated
PM10 were not from the blast furnaces and sinter plant stack, but rather due to wind-raised
dust from the blending plant or from the most likely potential source ‘activities’ on the
steelworks. To further understand the processes leading to elevated PM, our study
considered campaign data collected at 4 sites (Little Warren; AURN - Margam Fire Station;
Princes Street; and Dyffryn School) in Port Talbot measured across 4 weeks of April/May
2012. The dataset comprised of daily PM10 and PM2.5 Partisol measurements of Cl, NO3,
nss-SO4, Na, NH4, K, Mg, Ca, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Sb, Ba, Pb, EC and OC.
This was complemented by hourly PMfine/coarse concentrations of Na; Mg; Al; Si; S; Cl; K;
Ca; Ti; Cr; Mn; Fe; Ni; Cu; Zn; Br; Sr; Pb and BC, measured by Streaker/PIXE analysis at
both the Little Warren and Fire Station (Lucarelli et al 2011) and Single Particle Mass
Spectrometer data (Taiwo et al, 2014b) and gas phase pollutant measurements (NO, NO2,
NOx, SO2, CO and O3) from the AURN site. These measurements were analysed, identifying
the chemical signatures of the increment in PM above the local background attributable to
the works in Port Talbot, using meteorology and gas phase pollutant concentrations to assist
in an apportionment to a sources in the steelworks albeit from a process or fugitive source.
References Hayes, E. T. and Chatterton, T. (2009) An independent review of monitoring
measures undertaken in Neath Port Talbot in respect of particulate matter (PM10). Project
Report. Welsh Assembly Government.
Detection of brake wear aerosols by aerosol time-of-flight
mass spectrometry
David Beddows, NCAS Researcher, University of Birmingham
Other Authors: Manuel Dall'Osto, Roy Harrison, Oluremi Olatunbosun
Brake dust particles were characterised using an Aerosol Time-of-Flight Mass Spectrometer
(ATOFMS) operated using two inlet configurations, namely the aerodynamic lens (AFL) inlet
and countersunk nozzle inlet. Laboratory studies show that dust particles are characterised
by mass spectra containing
ions deriving from Fe and Ba and although highly correlated to each other, the Fe and Ba
signals were mostly detected using the nozzle inlet with relatively high laser desorption
energies. When using the AFL, only [ 56 Fe] and [ -88 FeO 2 ] ions were observed in brake
dust spectra generated using lower laser
desorption pulse energies, and only above 0.75 mJ was the [ 138 Ba] ion detected. When
used with the preferred nozzle inlet configuration, the [ -88 FeO 2 ] peak was considered to
be the more reliable tracer peak, because it is not present in other types of dust (mineral,
tyre, Saharan etc). As shown by the
comparison with ambient data from a number of locations, the aerodynamic lens is not as
efficient in detecting brake wear particles, with less than 1% of sampled particles attributed
to brake wear. Five field campaigns within Birmingham (background, roadside (3) and road
tunnel) used the nozzle inlet and
showed that dust particles (crustal and road) accounted for between 3.1 and 65.9% of the
particles detected, with the remaining particles being made up from varying percentages of
other constituents.
ERA5 - the replacement for ERA-Interim
Paul Berrisford, Scientist, NCAS-Climate, ECMWF
ERA5 will be the replacement for ERA-Interim, ECMWF's current reanalysis using the full
observing system. Production has recently begun with four parallel experiments and is
expected to take two years to complete. Following completion, consolidation to a publishable
experiment will be carried out, so the data are expected to be available by the end of 2017.
Preparation of the "reanalysis system", which has been ongoing for some time, will be
described, including the IFS model cycle, input data, bias correction, configuration and postprocessing. Methods of access to the various data products will also be discussed.
Managing drought risk in Africa
Emily Black
Agricultural drought in Africa can cause humanitarian catastrophe. Robust and reliable
information on meteorological conditions can reduce the impact of drought, both through
early warning of adverse conditions and through financial instruments, such as drought
insurance. In Africa, however, monitoring the weather is challenging because of the
heterogeneity of the climate and the sparcity of the observing network. The link between
rainfall deficit (meteorological drought) and dry soil (agricultural drought), furthermore, varies
in both space and time. Remotely sensed rainfall is increasingly being used to manage
climate-related risk in Africa. Applications based on such data must make maximal use of
the skill of the methodology in order to avoid doing harm by providing misleading
information. This is especially challenging in regions, such as Africa, which lack gauge data
for validation. In this study, we show how calibrated ensembles of equally likely rainfall can
be used to infer uncertainty in remotely sensed rainfall estimates, and subsequently in
assessment of drought. We illustrate the methodology through a case study of drought
insurance in Zambia. In order to investigate the transition from meteorological to agricultural
drought and the propagation of uncertainty from rainfall to soil moisture estimation, we drive
a land surface model with rainfall ensembles. Although our study focuses on agricultural
insurance, the methodological principles for application design are widely applicable in Africa
and elsewhere.
Development and application of UK sub-daily rainfall
datasets
Stephen Blenkinsop, Senior Research Associate, Newcastle
University
Other Authors: Steven Chan, Hayley Fowler, Elizabeth Lewis
Intense sub-daily rainfall may be associated with flash flooding, such as the events at
Boscastle in August 2004 and Newcastle upon Tyne in June 2012. Given the prospect of an
intensification of short-duration rainfall in a warming climate, the availability of high-quality
observed datasets on these timescales is essential to understand historical climate variability
as well as the drivers of intense rainfall. We therefore describe the development of new
hourly and 15 minute;rainfall datasets for the UK based on ~1600 raingauges from three
different data sources including tipping bucket raingauge data from the UK Environment
Agency. Significant problems in the use of such data for the analysis of extreme events are
identified, including the recording of accumulated totals, high frequency bucket tips and the
unrecorded non-operation of gauges. A series of procedures developed to quality control this
new dataset are described.
The seasonal climatology of UK hourly rainfall extremes based on the analysis of ~380
gauges with near-complete records for 1992-2011 is described. The highest frequencies and
intensities of hourly extremes occur during summer when the usual orographically defined
pattern of extremes is replaced by a weaker, north-south pattern. A strong diurnal cycle in
hourly extremes, peaking in late afternoon to early evening is also identified in summer, and
for some areas, in spring. This likely reflects the different mechanisms that generate subdaily rainfall, with convection dominating during summer when, typically, 50% of daily rainfall
totals in south east England are also derived from one hour bursts. A scaling relationship
between intense hourly rainfall and temperature that approximates that described by the
Clausius-Clapeyron relation is also noted in summer and could provide a mechanism for the
intensification of hourly rainfall under a warming climate.
The resulting quality controlled dataset will provide considerable value in several contexts
including validation of the new generation of very high resolution climate models, improved
understanding of rainfall generating processes and the construction of a gridded hourly
rainfall dataset.
Low Cost Ceilometers and Air Quality Predictions
Michael Brettle, Product Manager, Optical Sensors, Campbell
Scientific Ltd
Other Authors: Josh Vande Hey
Air quality models are in widespread use for predicting pollution levels in urban areas. Like
any model they are limited by the input data available. Surface weather data and current
pollution levels can be obtained relatively easily, albeit sensor location can be problematic.
The mixing layer height (MLH) is a very useful parameter and relatively site independent.
This poster will describe how inexpensive ‘off-the-shelf’ ceilometers can measure MLH and
some results of using MLH measurements in an air quality application.
Attribution of the Wettest May in South-Eastern China for
40 years
Claire Burke, Attribution Scientist, Met Office
Other Authors: Peter Stott, Ying Sun
During 2015 several provinces in south-eastern China experienced their wettest May in 40
years. This resulted in severe flooding with impacts including loss of life. We examine the
change in precipitation quantity, duration and intensity during May in terms of daily totals,
number of consecutive days of rain and intensity of rainfall. We use model data from
ensemble experiments with and without anthropogenic forcings generated with an upgraded
version of HadGEM3-A, which has higher resolution than any other global model currently
used for attribution, and other models available under the C20C initiative. Here we will
present the changes in probability for rainfall intensity and duration as a result of
anthropogenic climate change. Preliminary results indicate that anthropogenic forcing may
be detectable for heavy rain in this region of China.
WRF Modelling of Ozone Transport in the West Pacific
Warm Pool
Richard Newton, PhD Student, SEAES, University of Manchester
The CAST campaign, along with sister campaigns CONTRAST and ATTREX, was an
aircraft and field campaign based in Guam and Manus Island, Papua New Guinea between
January and March 2014. The field campaign in Manus Island consisted of ground
measurements and ozonesonde launches. One of the observations from the ozonesonde
data was a low-ozone event in the tropical tropopause layer on 21-23 February, which was
traced to the outflow from a marine convective system that pumped ozone-deficient air into
the tropopause region. This air was advected by an easterly jet over Manus Island, where it
was measured by the ozonesondes.
This low-ozone event has prompted further investigation using the Weather Research and
Forecasting (WRF) model. The model has been run for the period between 17-23 February
to investigate its ability to reproduce the conditions that produced the low-ozone event. The
model output was compared with the ground measurements and ozonesonde
measurements from Manus, and tracers were used to understand how efficient the
convective systems are at lifting air from the surface or lower troposphere into the
tropopause. Furthermore, the sensitivity of particular physics options to the experiment was
investigated. Future work will be focused on finding other instances of the low-ozone
phenomenon in the tropopause layer in order to determine their typical frequency, size and
longevity.
Stories from the Arctic field
Michelle Cain, PDRA, University of Cambridge
I will discuss my experience co-ordinating a range of communication activities for a multiuniversity research programme called Methane in the Arctic: Measurements and Modelling.
The project included ground- and aircraft based fieldwork in the European Arctic, as well as
computer modelling. Our communication activities included: our own field blog
(www.arcticmethane.wordpress.com), which was syndicated to the Scientific American
Expeditions blog; writing articles for other blogs with a wider audience than our own; use of
twitter; and podcasting our field work. The finale to our communications work was a live
event at a science festival, in which we took the audience along with us on a recreated
research flight, complete with a life-size mock up of a section of our research aircraft. I will
discuss my experiences of these forms of communication, and give an evaluation of their
successes and failures.
Evaluation of Mechanisms of Extreme Temperatures Over
Europe
Ioana Colfescu
Other Authors: Gabriele Hegerl, Simon Tett
Central Europe and the United Kingdom monthly-scale changes in location, intensity and
probability of temperature extreme events are quantified and compared for three different
periods using 20th Century Reanalysis version 2c ensemble mean. The extreme events
calculation is based on a composite analysis and the temporal linear trend for each region is
considered to be a good approximation of the externally forced component while the
remaining part to be internal variability. For hot and cold events of five and three days
composites of all occurrences above and below the 95th and 5th respectively are calculated
for 1920-1950, 1951-1980 and 1981-2011 for the internal and total components. The
circulation patterns associated with the extreme events are calculated as the composites of
the 500mb geopotential height found at each occurrence of cold or hot temperature event.
Differences between the composites of the most recent period and the other two are
analysed for both temperature and circulation. A Mann-Whitney test is used to evaluate the
statistical significance of the differences. Preliminary mechanisms for the changes found are
evaluated using radiation, sensible heat flux lead-lag correlations with respect to the events.
Our findings suggest no changes in the temperature and their associated circulation patterns
for hot events over the regions of study. The inclusion of the trend ( i.e external forcing)
doesn't overall change the temperature patterns either for these regions. However, areas
where significant differences are found in the North Atlantic and Greenland when the trend is
included and suggest an overall warming for these regions. For the cold events, significant
cooling over Europe and heating over Greenland is found with respect to 1920s while
cooling over the central Atlantic can be seen with respect to the 1950s period. The
associated circulation patterns show a consequent strengthening of the circulation over
Greenland and a weakening over Scandinavia. In comparison to the 1950s heating of the
North Atlantic seen in the recent period is found to be suppressed when the external forcing
is not removed.
Origins and trajectories of dust affecting the clouds in the
ICE-D region
Zhiqiang Cui, Institute for Climate and Atmospheric Science,
University of Leeds
Other Authors: Lindsay Bennett, Alan Blyth, Tom Choularton, Richard Cotton, Paul
Field, Martin Gallagher, Jim McQuaid, Ben Murray, Ryan Neely, Hannah Price
The field campaign of the Ice in Clouds Experiment - Dust (ICE-D) took place in the Cape
Verde region during August 2015. Aircraft measurements were made of aerosol, cloud
microphysics, and meteorological variables to investigate how the mineral dust transported
from African continent affect convective clouds in the Cape Verde region. Aerosol data were
analysed to study the vertical structure of the dust. The layered structures were found in
most of the cases. The top of the dust layer aloft could reach around 5 km. The aerosol in
the lowest 2 km above the sea surface usually decreased with altitude. Back trajectory
analyses suggested there were two origins of dust aerosol for some cases. The upper dust
layer originated from the Niger and Mali region and was transported with the easterly winds,
whilst the lower dust particles were from the Mauritania and West Sahara region. Satellite
dust products suggest at least in some cases the dust layer was polluted, i.e., externally
mixed with smoke. We will use numerical models to study how the aerosol size distribution,
chemical composition and mixing state affect convective clouds.
High resolution modelling of the initiation and
development of convective clouds in ICE-D
Zhiqiang Cui, Institute for Climate and Atmospheric Science,
University of Leeds
Other Authors: Alan Blyth, Tom Choularton, Paul Field, Martin Gallagher, Yahui
Huang, Annette Miltenberger
During the transition from dry season to wet season in the Cape Verde region in August,
dust aerosol particles transported with the Sahara Air Layer from the African Continent
sometimes meets the convective clouds in the moist air. Since mineral dust is a major
source of ice nuclei, the dust along with other types of aerosol can affect the microphysics
and precipitation of convective clouds. The state-of-art instruments board on the research
aircraft Bae 146 measured the cloud microphysics at certain levels during various cloud
development stages. We will use models with high resolutions to study the initiation and
development of convective clouds in the ICE-D field campaign. The modelling results will be
compared with the observations with different freezing parameterizations.
Volunteered Crowdsourced Extreme Weather Data in the
United Kingdom
Robert K. Doe, Director, Tornado and Storm Research Organisation
(TORRO)
The benefits of volunteered, crowdsourced, extreme weather data are enormous. For over
forty years the Tornado and Storm Research Organisation (TORRO) has developed and
encouraged public participation in a number of datasets relating to meteorological extremes.
These data have been continually updated and quality controlled. These datasets include
tornadoes, thunderstorms, hailstorms, lightning impacts, snowfalls, coastal storms, and also
maxima and minima extreme temperature. Once analyzed these data produce results of
significant scientific value. This poster highlights some of the major data achievements and
key results, examines some of the challenges ahead including investigating relationships
between these data; the new opportunities technology can provide and the importance of
citizen science in contributing to our knowledge and understanding of meteorological
extremes in the United Kingdom.
Understanding the rapid summer warming and changes in
temperature extremes since the mid-1990s over Western
Europe
Buwen Dong
Other Authors: Len Shaffrey, Rowan Sutton
Analysis of observations indicates that there was a rapid increase in summer (June-August,
JJA) mean surface air temperature (SAT) since the mid-1990s over Western Europe.
Accompanying this rapid warming are significant increases in summer mean daily maximum
temperature (Tmax), daily minimum temperature (Tmin), annual hottest day temperature
(TXx) and warmest night temperature (TNx) and an increase in frequency of summer days
(SU) and tropical nights (TR), while the change in the diurnal temperature range (DTR) is
small. This study focuses on understanding causes of the rapid summer warming and
associated temperature extreme changes since the mid-1990s over Western Europe. A set
of experiments using the atmospheric component of the state-of-the-art HadGEM3 global
climate model have been carried out to quantify relative roles of changes in sea surface
temperature (SST)/, sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and
anthropogenic aerosols (AA). Results indicate that the model forced by changes in all
forcings reproduces many of the observed changes since the mid-1990s over Western
Europe. Changes in SST/SIE explain 62.2% ± 13.0% of the area averaged seasonal mean
warming signal over Western Europe, with the remaining 37.8% ± 13.6% of the warming
explained by the direct impact of changes in GHG and AA. Results further indicate that the
direct impact of the reduction of AA emissions over Europe of changes in AA, mainly through
the changes in cloud concentration nuclei and aerosol optical depth with additional positive
feedbacks from land surface drying and the reduction in cloud cover the reduction of
emissions over Europe, is a key factor for increases in annual hottest day temperature and
in frequency of summer days. It explains 45.5% ± 17.6% and 40.9% ± 18.4% of area
averaged signals for these temperature extremes. The direct impact of aerosol changes acts
to increase DTR, but the change in DTR is countered by the direct impact of GHG forcing. In
the next few decades, greenhouse gas concentrations will continue to rise and
anthropogenic aerosols emissions over Europe and North America will continue to decline.
Our results suggest that the changes in summer seasonal mean SAT and temperature
extremes over Western Europe since the mid-1990s are most likely to be sustained or
amplified in the near term, unless other factors intervene.
The onset and cessation of seasonal rainfall over Africa
Caroline Dunning, PhD Student, University of Reading
Other Authors: Philip Richard Allan, Emily Black
The onset of the rainy season marks the beginning of the growing season and determines
planting dates, and is therefore of key importance to millions of African farmers. The
beginning and end of the wet season is determined using cumulative daily mean rainfall
anomalies from 5 observational datasets and the ERA Interim reanalysis in order to
investigate seasonality of rainfall over Africa. The method objectively classifies regions into
those which experience one or two wet seasons per year and determines onset and
cessation dates. Agreement in onset and cessation dates between datasets to within one
standard deviation over most regions, and comparisons with previous work, confirm that the
method is robust and accurate. Consistency in both temporal and spatial variability in onset
and cessation dates indicates a good representation of the seasonal cycle in the
observational and reanalysis datasets, although ERA Interim and the ARC observational
dataset exhibits some differences. Onset displays higher temporal and spatial variability than
cessation, which is less well defined due to slower progression. The coastal region of Ghana
and the Ivory Coast experiences two wet seasons per year, the first lasting from 3 April -28
June, and the second from 18 September - 9 November (on average). The successful
applicability to multiple datasets demonstrates its suitability for future studies on seasonal
African precipitation.
Observations of cloud microphysics and ice formation
during COPE
Martin Gallagher
Other Authors: Lyndsay Bennett, Alan Blyth, Keith Bower, Phil Brown, Thomas
Choularton, Jonathan
Croiser, James Dorsey, Michael Flynn, Yahui Huang, Alexei Korolev, Zixian Liu,
Jonathan Taylor, Paul Williams
Intense rainfall generated by convective clouds is a major source of flash flooding in many
parts of the world. Understanding the microphysical processes leading to the formation of
precipitation is one of the main challenges in improving our capability to make quantitative
precipitation forecasts. Here, we present microphysics observations of cumulus clouds
measured over the South-West Peninsula of the UK during the COnvective Precipitation
Experiment (COPE) in August 2013. Our multi-platform approach focuses on airborne in situ
measurements, which are framed into a wider context using complementary ground-based
and airborne radar data. We present details of the observations made during 1 case study
on 3 August 2013.
Observations of the microphysics of a cloud system in
ICE-D
Martin Gallagher
Other Authors: Alan Blyth, Keith Bower, Thomas Choularton, Richard Cotton,
Jonathan Crosier, Gary Lloyd, Jonathan Taylor
The ICE-D project was conducted during the summer of 2015 in the region of the Tropical
North Atlantic close to Cape Verde. This is a region frequently affected by eastward
convective clouds and cloud clusters. These clouds are frequently affected by large
quantities of dust raised and advected from the Sahara desert. The convective clusters
forming in this region frequently evolve into Tropical storms and Hurricanes over the Atlantic
ocean. It is hypothesised that the glaciation process is key to the development of these cloud
systems. In this paper we present measurements made of the cloud microphysics and
dynamics made during a case study forming part of this project. We investigate the origin of
the ice phase in the cloud and the relative importance of secondary and primary ice in
controlling the evolution of the cloud.
Detection and Analysis of High Ice Concentration Events
and Supercooled Drizzle from the IAGOS Commercial
Aircraft Database
Martin Gallagher
Other Authors: Darrel Baumgardner, Karl Beswick, Matt Freer, Gary Lloyd
Hazardous encounters with high ice concentrations that lead to temperature and airspeed
sensor measurement errors, as well as engine rollback and flameout, continue to pose
serious problems for flight operations of commercial air carriers. Supercooled liquid droplets
(SLD) are an additional hazard, especially for smaller commuter aircraft that do not have
sufficient power to fly out of heavy icing conditions or heat to remove the ice. New
regulations issued by the United States and European regulatory agencies are being
implemented that will require aircraft below a certain weight class to carry sensors that will
detect and warn of these types of icing conditions. Commercial aircraft do not currently carry
standard sensors to detect the presence of ice crystals in high concentrations because they
are typical found in sizes that are below the detection range of aircraft weather radar.
Likewise, the sensors that are currently used to detect supercooled water do not respond
well to drizzle-sized drops. Hence, there is a need for a sensor that can fill this measurement
void. In addition, the forecast models that are used to predict regions of icing rely on pilot
observations as the only means to validate the model products and currently there are no
forecasts for the prevalence of high altitude ice crystals. Backscatter Cloud Probes (BCP)
have been flying since 2011 under the IAGOS project on six Airbus commercial airliners
operated by Lufthansa, Air France, China Air, Iberia and Cathay Pacific, and measure cloud
droplets, ice crystals and aerosol particles larger than 5 µm. The BCP can detect these
particles and measures an optical equivalent diameter (OED) but is not able to distinguish
the type of particle, i.e. whether they are droplets, ice crystals, dust or ash. However, some
qualification can be done based on measured temperature to discriminate between liquid
water and ice. The next generation BCP (BCPD, Backscatter Cloud Probe with polarization
detection) is now undergoing performance testing and can differentiate atmospheric particle
types. Given that the BCP and BCPD are both single particle detectors, this permits high
sensitivity to the smallest quantities and rapid detection (within seconds) to alert flight crews.
The BCPD is being implemented as part of a near real-time, flight forecasting system that
uses satellite and models, coupled with in situ measurements from the BCPD and
meteorological sensors. This presentation will describe the essential components of such a
system and how it will be implemented to optimize aircraft flight paths while minimizing
potential hazards. Examples of measurements from the BCPD will be given that
demonstrate its capability for detection and differentiation of atmospheric particulates,
especially supercooled liquid droplets and ice crystals, in near real-time.
Observing the influence of atmospheric transport
pathways on iodine species and particle formation at a
coastal site in Antarctica
Zoë Fleming, NCAS Research scientist, long term trace gases,
National Centre for Atmospheric Science, University of Leicester
Other Authors: Stephen Edmundson, Anna Jones, Peter Fretwell, Howard Roscoe
The Met Office’s NAME dispersion model has been used to create 10 day back footprints,
highlighting the pathways of air arriving at the Halley measurement station. Halley is located
6 km from the coast, on the Brunt ice shelf and over 10 km from the ice sheet that covers the
Antarctic continent. There is a large seasonal variation in sea ice cover on the ocean near
the station, often revealing patches of open water during the summer months. Iodine
compounds (including IO) have been known to form on sea ice and can have a large effect
on ozone photochemistry and also be implicated in particle formation. With this long term
analysis of sea ice, open water and even long range pollution effects from South America
and South Africa can be detected and related to the chemistry of the airmasses arriving at
Halley.
The contribution of sting-jet windstorms to extreme wind
risk in the North Atlantic
Suzanne Gray, Professor of Meteorology, Dept. of Meteorology,
University of Reading
Other Authors: Peter Clark
Wind storms are a major winter weather risk for many countries in Europe. These storms are
predominantly associated with explosively-developing extratropical cyclones that track
across the region. A substantial body of literature exists on the synoptic dynamics,
predictability and climatology of such storms. More recently, interest in the mesoscale
variability of the most damaging winds has led to a focus on the role of sting jets in
enhancing wind storm severity. We present a present-era climatology of North Atlantic
cyclones that had potential to produce sting jets. Considering only explosively-developing
cyclones, ones with sting-jet potential are more likely to have higher relative vorticity and
associated low-level wind maxima. Furthermore, the strongest winds for sting-jet cyclones
are more often in the cool-sector, behind the cold front, when compared with other
explosively-developing cyclones, which commonly have strong warm-sector winds too. The
tracks of sting-jet cyclones, and explosively-developing cyclones in general, show little offset
from the climatological storm track. While rare over Europe, sting-jet cyclones are relatively
frequent within the main storm track with up to one third of extratropical cyclones exhibiting
sting-jet potential. Thus, the rarity and, until recently, lack of description of sting-jet
windstorms is more due to the climatology of storm track location away from highlypopulated land masses, than due to an actually rarity of such storms in nature.
High Impact Weather events observed at the NERC MST
Radar Facility at Aberystwyth
David Hooper, NERC MST Radar Facility Project Scientist, NCAS
The NERC MST Radar Facility at Aberystwyth is a field station that is run on behalf of the
UK's atmospheric science community. The MST (Mesosphere-Stratosphere-Troposphere)
radar profiles the atmosphere over the altitude range 2 - 20 km. It primarily measures wind
and atmospheric structure. It is operated on a continuous basis. The Facility operates a
number of auxiliary instruments. This poster gives examples of 3 high impact weather events
observed by the Facility's instruments: a Sting Jet (a localised but extreme wind event), a
Tornado, and a heavy rain/flooding event.
The measurement and modelling of rainfall drop size
distributions at the Chilbolton Facility for Atmospheric and
Radio Research
Judith Jeffery, Lidar and meteorological instruments manager,
STFC Rutherford Appleton Laboratory
Other Authors: K’ufre-Mfon Ekerete, Francis Hunt, Ifiok Otung
The measurement and modellig of the drop size distribution (DSD) of rainfall is vital in
quantifying rainfall rates and accumulations and also in predicting the impact of rainfall on
radiocommunications. The use of rainfall radar to predict rainfall occurring at the ground over
a wide area depends on a calibration of the radar reflectivity as a function of drop size.
Ground-based measurements of DSD in the vicinity of the radar provide valuable calibration
data. During extreme weather events it is also vital that radiocommunications are
maintained, for example for the coordination of emergency responses. As microwave
frequency increases, so does the attenuation due to rainfall, and this must be mitigated for in
system design. Models of rainfall statistics for different world climate regions are essential for
this application. At the Chilbolton Facility for Atmospheric and Radio Research (CFARR)
long-term measurements of DSD have been made using a variety of instruments. They fall
into two measurement types - sensing drop sizes via the impact made by drops on a surface
or by using optical systems to detect and size drops. The respective strengths and
weaknesses of these techniques will be described. Work is also in progress to fit CFARR
DSD data using new models, in conjunction with the Mobile and Satellite Communications
Research Group of the University of South Wales. In particular the Gaussian Mixture Model
is being trialled as a suitable method for fitting the multimodality of DSDs. The current status
of this research will be discussed.
A gridded hourly rainfall dataset for the UK
Elizabeth Lewis, Research Associate, Newcastle University
Other Authors: Paul Bates, Stephen Blenkinsop, Gemma Coxon, Hayley Fowler, Jim
Freer, Niall Quinn, Ross Woods
A new 1km gridded hourly rainfall dataset for the UK has been created by disaggregating the
daily Gridded Estimates of Areal Rainfall (CEH-GEAR) data set using comprehensively
quality-controlled hourly rain gauge data from over 1300 observation stations across the
country. Quality control measures include identification of frequent tips, daily accumulations
and dry spells, comparison of daily totals against the CEH-GEAR daily dataset, and nearest
neighbour checks. The quality control procedure was validated against historic extreme
rainfall events and the UKCP09 5km daily rainfall dataset. The hourly gridded rainfall product
has great potential for use in many hydrological applications that require high temporal
resolution meteorological data. One important example of this is flood risk management, with
flooding in the UK highly dependent on sub-daily rainfall intensities amongst other factors.
Knowledge of sub-daily rainfall intensities is therefore critical to designing hydraulic
structures or flood defences to appropriate levels of service. Sub-daily rainfall rates are also
essential inputs for flood forecasting, allowing for estimates of peak flows and stage for flood
warning and response. In addition, an hourly gridded rainfall dataset has significant potential
for practical applications such as better representation of extremes and pluvial flash flooding,
validation of high resolution climate models such as the model used in the CONVEX project
and improving the representation of sub-daily rainfall in weather generators.
Atmospheric drivers of European drought events
Ronald Li, PhD Student, Atmospheric, Oceanic and Planetary
Physics, University of Oxford
The 2003 European summer heatwave is associated with persistent or recurring
atmospheric patterns, like for example waves and jet shifts. This brings up the rsearch
questions of how changes in background states affect wave propagation, and whether we
can understand where waves in individual periods come from. Examples of the different
background states considered include the North Atlantic Oscillation, the East Atlantic
pattern, and the Atlantic jet. Using methods like temporal filtering, empirical orthogonal
functions, and Rossby wave propagation theory, we examine how these different
background states allow different wave propagation, and assess their roles with the 2003
European heatwave.
The role of data recovery and historical climate records in
understanding High Impact Weather
Mark McCarthy, Manager of National Climate Information Centre,
Met Office
Other Authors: Malcolm Allan, Christine Duffy, Timothy Legg, Sarah Pankiewicz,
Catharine Ross, Martyn Sunter
The study of rare high impact weather and extreme events benefits from having long
observational records to provide historical context and a sufficiently large sample of events
for robust statistical analysis. The UK benefits from the substantial efforts of George Symons
in the late 19th Century, and many others since, to both standardise the methods of
measurement and also recognise the high value of historical observations. This legacy has
left us with rich historical meteorological data for the UK. However a large majority of our
observational data prior to about 1960 remains in paper archives, while modern meteorology
and climate research continue to work toward increasing demands for more localised
information in both space and time. In this poster we present a number of recent activities at
the Met Office to supplement our digital meteorological archives from paper records such as
daily climatological returns from observing stations, to monthly rainfall recorded in the British
Rainfall publication since 1862. We will conclude with some case studies showing the impact
of these additional data on our representation of some historical high impact weather and
climate events.
A High Resolution Measurement Station for Baseline
Studies Related to Unconventional Petrochemical
Extraction Activities in the UK. 2015 Preliminary CO2 and
CH4 Results
Iq Mead, Lecturer, Cranfield University
As the potential for extraction of hydrocarbon reservoirs using unconventional methodologies
e.g. hydraulic fracturing is explored in the UK the need for robust methodologies for
quantification of potential impacts has become pressing. To fully quantify any potential risks
or impacts of extraction activities on air quality and greenhouse species distributions a
detailed climatology of existing conditions is needed. Crucially, this is needed at the local
scale in the areas where operations are proposed over an extended period before extraction
related activities. Expanses of the Northern UK have now been made available for
explorative drilling associated with onshore shale oil and gas reservoirs. In expectation that
there would be some form of activity related to the petrochemical industry in this region a
new routine measurement station was implemented at a site in the North West UK in late
2014. The potential impact of activates such as hydraulic fracturing in modulating
distributions of greenhouse and air quality species in the UK are poorly characterised and
may be dissimilar to those described in US studies. It is therefore clear that air monitoring is
needed at local scales prior to exploration or extraction activities to assess both potential
impacts and future reporting needs. Use of high resolution ground based sampling
technologies for regulation and hotspot screening studies is an established methodology.
Suitably located and pre-emptively operational stations provide an overview of changes in
emission sources and distributions. This is key to understanding the impacts of these types
of under characterised extraction activities. There is a requirement for high information
content data for the characterisation of fugitive and overall emissions for compliance studies,
mitigation analysis and the contextualisation of emissions in terms of regional and national
inventories. This manuscript describes preliminary data from an ongoing study which
demonstrates both the utility of pre-emptive and then continuing targeted monitoring and its
critical importance in understanding composition changes associated with emerging
extraction activities.
A Global Climatology of Upper-Tropospheric Cut-off lows
Cristian Muñoz, PhD student, School of Earth, Atmospheric and
Environmental Sciences. The University of Manchester
Other Authors: David Schultz, Geraint Vaughan
Cut-off lows are upper-level low-pressure areas formed on the equatorward side of the polar
or subtropical jet stream. They develop from a trough that experiences a marked tilting and
subsequent breaking off, leaving a pool of cold air and cyclonic circulation detached from the
extratropical wave. These systems constitute an important feature of upper-level midlatitude
weather systems because they can favour, along with a sudden development of deep
convection on its eastern flank and a surface cyclone, an increase in the tropospheric ozone
concentration through a stratospheric-tropospheric exchange mechanism. Previous work
studying each hemisphere independently using different approaches has shown that cut-off
lows in the Northern Hemisphere have a different behavior compared to those in the
Southern Hemisphere. Whereas cut-off lows in the Northern Hemisphere occur mostly
during the late warm season and at lower isentropic surfaces (320–330 K), cut-off lows in the
Southern Hemisphere occur year round at higher isentropic surfaces during the late summer
(325–350 K) and at lower isentropic surfaces during the winter.
The University of Leicester is developing a new multi-sensor platform for characterizing
urban air quality. SOGS (small, open, general-purpose sensor) combines a high quality 32channel datalogger and solar battery charger with a flexible interface for supporting both
analog and digital instruments. Recent work with the system has been focused on the use
of Metal Oxide Semiconductor (MOS) gas sensors in urban air quality monitoring, due to
their potentially high sensitivity and low cost. This kind of sensor is widely used in industrial
warning systems thanks to its responsiveness to a broad range of gasses, but that same
feature has limited their utility for serious pollution monitoring. Field testing and modelling
work have led to a prototype low cost instrument design with promising accuracy and
precision. This poster will address the use and current limitations of MOS gas sensors,
including their calibration, best practices for reliable atmospheric monitoring instrument
design using MOS in-situ sensors, the design of the SOGS instrument platform and show
preliminary calibration results.
Flood and Water Management Applications of High
Resolution Dual-Polarisation X-band Radar in Northern
Scotland
Ryan R Neely III, Lecturer of Observational Atmospheric Science
NCAS and the University of Leeds
Other Authors: Lindsay Bennett, Alan Blyth, Christopher Collier, David Dufton
As part of SEPA’s Flood Warning Strategy (2012-2016), SEPA has committed to increasing
their understanding of the spatial representation and real time measurement of rainfall.
Activities associated with this include reviewing the UK's weather radar network and its
suitability for flood warning provision and making recommendations for future improvements
(including new and temporary installations to help increase the probability of detection (POD)
of intense rainfall by radar).
In order to meet this strategic objective SEPA has partnered with NCAS and the University
of Leeds' School of Earth and Environment to conduct a pilot project in the North of Scotland
from January to August 2016 using the NCAS Mobile X-band Weather Radar (MXWR).
Thus, the overall aims of this work is to answer:
1) What are the benefits of high temporal and spatial resolution radar precipitation estimates
for flood forecasting in Northern Scotland?
2) How do dual-polarisation radar observations improve rainfall estimates used in flood
forecasting?
Here we show examples from the ongoing observations that start to show the benefit of the
high resolution radar data under various high impact events.
Systematic assessment of hydrological drought
termination in observed and reconstructed river flow
records
Simon Parry, Hydrologist Centre for Ecology & Hydrology and
Loughborough University
Other Authors: Christel Prudhomme, Katie Smith, Rob Wilby, Paul Wood
Drought termination has often been characterised as an abrupt return to ‘normal’ conditions,
although this may reflect a reporting bias towards extreme transitions that are more
memorable. An objective approach is necessary to identify and characterise the full range of
variability in drought terminations. Whilst there are a number of long observed river flow
time series in the UK, the use of river flow reconstructions allows a more comprehensive
assessment of drought termination in the historical record. A catalogue of drought
termination events from a previous study is supplemented by additional events identified in
river flow reconstructions from 1910 onwards produced by the GR4J lumped catchment
hydrological model. Results from 24 catchments across Great Britain show that droughts
and drought terminations occurred more frequently in the predominantly reconstructed
period (1910-1960) than the observed period (1960-2010), with the reconstructed data
highlighting the importance of major events in 1921-22, 1933-35 and the 1940s. Taking the
events derived from reconstructed and observed river flows together, the pre-instrumental
period contains most of the events with the highest drought termination rates, highlighting
the value of the reconstructed data. The increased sample size of drought termination
events provides a more robust historical context in which to place contemporary events.
Challenges in using metal oxide sensors for air quality monitoring
Philip Peterson, Postgraduate Research Student, University of
Leicester
The University of Leicester is developing a new multi-sensor platform for characterizing
urban air quality. SOGS (small, open, general-purpose sensor) combines a high quality
datalogger and solar battery charger with a flexible interface for supporting both analog and
digital instruments. Recent work with the system has been focused on the use of Metal
Oxide Semiconductor (MOS) gas sensors in urban air quality monitoring due to their
potentially high sensitivity and low cost. This kind of sensor is widely used in industrial
warning systems thanks to its responsiveness to a broad range of gasses, but then at same
feature has limited their utility for serious pollution monitoring. Field testing and modelling
work have led to a prototype low cost instrument design with promising accuracy and
precision
This poster will address the use and current limitations of MOS gas sensors, including their
calibration, best practices for reliable atmospheric monitoring instrument design using MOS
in-situ sensors, the design of the SOGS instrument platform and show preliminary calibration
results.
Α synoptic climatology of peak wind power generation
events over Great Britain using Self-Organizing Maps
Kostas Philippopoulos, Research Scientist, University of Reading
Other Authors: David Brayshaw, John Methven
In the recent years wind energy penetration has increased significantly and in the near future
it is expected to cover a larger fraction of electricity demand, as a part of the global
renewable energy transition. However, due to the increased near-surface wind variability, the
integration of wind power in the electric grid imposes some significant challenges on its
stability and reliability. Peak wind power generation events are of particular interest in terms
of power system management as the inefficient use of large amounts of wind power leads to
significant complications on system operations. The motivation of the current research is to
examine the atmospheric circulation effects on these events, focusing on national
aggregated values over the Great Britain. The analysis is based on an ‘environment-tocirculation’ synoptic climatology approach since our goal is to identify the atmospheric
circulation patterns that are specifically associated with peak wind power generation events.
These events are identified using the synthetic 34-year (1980 – 2013) hourly time series of
GB-aggregated wind power generation (Cannon et al., 2015). The peak values correspond
to time series peaks that are higher than 80% and separated by at least four-hour intervals.
For the selected events the sea-level pressure (SLP) and the geopotential height at the
500hPa level (Z500) fields for a domain centered over the study area are extracted from the
MERRA reanalysis dataset. These fields are used as the input of the atmospheric circulation
classification procedure, which is based on competitive learning and on the use of SelfOrganizing Maps (SOM). The classification results to a two-dimensional map of atmospheric
circulation patterns (SOM feature map) where the neighboring nodes (patterns) are interconnected and each one is associated with the SLP and Z500 composites. The optimum
number of nodes is selected based on the quantitative evaluation of the results using a set of
cluster validation indices along with SOM specific quality measures. The optimum size of the
SOM feature map contains nine patterns organized in a 3x3 hexagonal lattice and additional
information regarding their interrelationships is obtained from the interpretation of the Umatrix. The results signify the importance of the westerly-component flow along with the
location and the proximity of the low-pressure centers to the British Isles. Special
consideration is given to the position and size of the cyclones relative to the actual wind farm
distribution over Great Britain. The study highlights the importance of large-scale
atmospheric circulation on peak wind energy power output events and the applied
methodology enables a more systematic investigation of the climate variability impacts on
extreme wind power production.
Processes controlling the diurnal cycle of moist
convection in the West African Sahel
Miroslav Provod
Other Authors: John Marsham, John Parker
Deep convection and mesoscale convective systems (MCSs) are integral components of the
West African Monsoon. The diurnal cycle in rainfall features a minimum around noon and a
peak at sunset. It is known that storms tend to initiate in the afternoon and evening and
MCSs persist through the night, but mechanisms underlying this diurnal cycle are poorly
understood and poorly represented by global models. Observational data, gathered during
the AMMA (African Monsoon Multidisciplinary Analysis) campaign, together with Unified
Model simulations, are used to study this diurnal cycle. The evening peak in initiations is
consistent with daytime heating reducing convective inhibition. The nocturnal monsoon flow,
and the embedded low-level jet (LLJ), bring moisture, increasing CAPE above the nocturnal
stable layer, which MCSs exploit. Furthermore, the LLJ provides favourable conditions for
MCSs by enhancing environmental shear to balance the vorticity of the MCS’s cold pools.
The nocturnal monsoon flow and the LLJ allow moisture flux convergence (MFC) into storms
to increase through the night, generating a secondary rainfall maximum around dawn. After
sunrise, boundary-layer (BL) mixing erodes the LLJ, providing less favourable shear and
decreasing MFC, and entraining dry air into the BL, decreasing CAPE: all three of these
processes combine to provide the rainfall minimum around midday. The results demonstrate
the importance of capturing the nocturnal LLJ and its interactions with organised moist
convection for modelling Sahelian rainfall and the monsoon.
Highlighting two NCAS Atmospheric Measurement
Facilities: “The Cape Verde Atmospheric Observatory
(CVAO)” and ‘The COZI-Lab”: What can and do they offer
to the UK community?
Katie Read, NCAS Research Scientist, AMF, NCAS,
University of York
The Cape Verde Atmospheric Observatory (CVAO, 16° 51’49 N, 24° 52’02 W) is a wellestablished Global Atmospheric Watch (GAW) measurement platform offering infrastructure
and supporting measurements in a remote subtropical marine boundary layer location. The
observatory celebrates 10 years of running this year during which it has supported science
from over 15 different countries and contributed to 30 publications. Long-term
measurements include many trace gases, greenhouse gases, and measurements of
chemical and physical aerosol parameters. Over the last two years, the COZI-Lab has
become a much-needed supporting lab for both campaign and long-term measurements,
such as those made at the CVAO. The lab allows instrumental development and calibration
methods to be perfected offline from the long-term measurements. It houses calibration setups relevant for ozone, carbon monoxide, nitrogen oxides and sulphur dioxide all referenced
to global calibration scales; providing a key service for the UK community. There is also
equipment, which allows temperature, pressure and humidity effects on the measurements
to be evaluated, and a cylinder filling facility. A manifold set-up ensures that additional
equipment can be run alongside the core instrumentation to facilitate intercomparison
experiments.
Monitoring air pollution transport from London to rural
areas using lidar
Hugo Ricketts, Research Scientist, NCAS/University of Manchester
Other Authors: Geraint Vaughan, David Wareing
The Clean Air for London (ClearfLo) Project took place in and around London. The aim of
the project was to learn how both atmospheric dynamics and chemistry affect air pollution in
the south east of England. During the winter and summer of 2012 many different types of
instrument including lidars were deployed throughout London city centre, suburbs and into
rural areas. Amongst these instruments was the Boundary Layer Aerosol/Ozone Lidar
owned by the National Centre for Atmospheric Sciences (NCAS). Ozone and aerosol data
are presented from data collected during July and August 2012 and compared to back
trajectories to identify their origins.
The Link between Atmospheric Blocking and Extreme
Events in Southeast South America
Regina R. Rodrigues, Associate Professor, Dept. of Geosciences,
Federal University of Santa Catarina, Brazil
Other Authors: Tim Woollings
Atmospheric blocking represents an important feature for regional climate and weather
patterns and plays an important role in extreme events, such as heat waves and droughts. In
spite of its importance, our knowledge of the physical mechanisms inherited to intensity and
frequency of atmospheric blocking is very limited, particularly for the Southern Hemisphere.
In this study, we investigate atmospheric blocking over east South America using different
indices in austral summer for the period of 1979-2014. Our results show that in general
blocking over this area is a consequence of propagating Rossby waves that grow to large
amplitudes eventually breaking anticyclonically over central South America. During blocking
episodes, the establishment of the South Atlantic Convergence Zone is inhibited causing
deficient rain over central South America and excess rainfall over the Amazon and southeast
South America. Moreover, persistent blocking can also lead to heat waves in South America
as well as warming of the western South Atlantic. Episodes of extreme events will be
presented.
Trends in historical heatwaves in the U.K.
Kate Salmon, Applied Scientist, Met Office
Other Authors: Michael Sanderson
There has been a long-term increase in the length and number of extreme hot days and
heatwaves in Europe since 1880, due to a combination of rising global temperatures, largescale atmospheric circulation changes and other natural climatic oscillations. Extreme
heatwaves can cause adverse social, economic and environmental effects; the summer
2003 heatwave caused the death of 2000 people in the U.K. alone as well as loss of
livestock, and buckling of railway tracks. Despite the enormous scale of these impacts, there
has been relatively little research into long-term trends of U.K. heatwaves during the last
century. This study uses U.K. observational temperature data collected since 1853 to
determine trends in the length, duration and intensity of U.K. heatwaves. Using stationspecific hot-day thresholds, we show that the length of heatwaves has significantly increased
at some stations since ~1930. Other stations, mainly coastal, experienced shorter
heatwaves in the 1960s, potentially due to lower sea surface temperatures, which could
indicate differences in long-term heatwave trends between coastal and inland stations. This
work, in association with the Health Protection Research Unit, will provide a baseline for
determining the future likelihood of extreme heatwaves, such as those in 2003 and 1976.
Global Occurrences and Causes of Tropospheric Inertial
Instability
Callum F. Thompson, PhD Student, University of Manchester
Inertial instability represents an imbalance between the pressure gradient and combined
Coriolis and centrifugal forces acting on an air parcel. Circulations resulting from the release
of this instability can enhance the outflow of convective storms, determine the location of
ITCZ convection, and possibly contribute to the organisation of banded precipitation. The
fact that the instability can feature in a variety of environments highlights the need for a
climatology to better understand tropospheric inertial instability. To do this, one must
determine a suitable criterion. A common criterion is when the absolute vorticity is the
opposite sign to the Coriolis parameter. However, there also exists criteria based on
potential vorticity and another incorporating flow curvature. Which criterion, if any, is most
suitable for diagnosing inertially unstable regions? A new climatology will be presented
displaying the merits of each criterion. Preliminary results for a 1979-2014 climatology show
the occurrence of unstable regions not just in the tropics, where it is most frequent, but also
extending into midlatitudes and even polar regions. At lower levels, there is a distinct
climatological signature in the North Indian Ocean during Northern Hemisphere summer.
However, establishing the areas most susceptible to instability is only one part of the puzzle.
With the criterion identified and applied to a climatology, the question of what causes the
formation of the instability will be addressed. Are there certain atmospheric environments
that promote inertial instability? How often are these environments realised? These are the
questions we wish to answer.
Free tropospheric aerosol observations by Raman lidar
Geraint Vaughan, Director of Observations, NCAS, University of
Manchester
Other Authors: Zoe Bradley, Hugo Ricketts
Over the summer of 2014 and 2015 the Raman lidar system at Aberystwyth observed
frequent occurrences of aerosol layers in the free troposphere, layers which are not
observed at other times of the year. The Raman lidar can measure the optical depth and
lidar ratio of these layers, giving an indication of their microsphysical properties. A summary
of the observations will be presented, together with evidence that the aerosol originates from
forest fires over North America. The hemispheric spread of absorbing aerosol, at a time of
year when the northern latitudes are illuminated by the Sun, suggests that there may be
implications for the Earth’s radiation budget.
The role of Mesoscale Instabilities in Sting-Jet Dynamics in
Windstorm Tini
Ambrogio Volonte, PhD Student, University of Reading
Windstorms often have large social and economic impact, usually due to strong gusts
related to low-level jets occurring along warm and cold fronts. Analysing the Great Storm
that affected the UK in October 1987, Browning (2004) and Clark (2005) highlighted the
existence of an additional region of strong surface winds in the frontal fracture area,
belonging to a descending airstream called “sting jet”. Despite a large body of work
performed since then, sting-jet dynamics is still not totally understood and our current
research aims to bridge this gap. This poster presents analysis of a sting jet identified in
Windstorm Tini (12 February 2014, surface gusts over 100 mph in Wales ) to highlight the
dynamical processes underpinning the airstream. Particular attention is devoted to the
evolution of atmospheric instabilities along the airstream, showing that both the release of
conditional symmetric instability and of inertial instability have a primary role in sting-jet
descent and acceleration. An analysis of the processes generating these instabilities is
performed, pointing out how filaments of negative absolute vorticity form in this curved and
frontolytic environment and at what extent they determine the dynamics of this strong and
narrow descending jet. The investigation is carried out through simulations run with the
MetUM, the operational forecast model of the UK Met Office, and back-trajectories are
largely used to gain further information on the dynamics of the sting jet.
Direct observations of wet radome attenuation at 94GHz
Chris Walden, Head, Chilbolton Facility for Atmospheric & Radio
Research, STFC/NCAS
Other Authors: John Bradford, Anthony Illingworth, Darcy Ladd, John Nicol
One of the objectives of the ACTRIS Research Infrastructure is to provide accurate
observational data on the variability of clouds. However, deriving reliable estimates of ice
water content from precipitating clouds is a significant challenge due to the large but
unknown radar attenuation by the wet radome protecting ground-based mm-wave radars.
This means that the observed pdfs of ice water content are biased and cannot be compared
with NWP model values. We present first results of a technique to measure the radome
attenuation directly in real time.
Diagnosing observation error statistics for SEVIRI
observations
Joanne Waller, PDRA, University of Reading
Other Authors: Sarah Dance, Graeme Kelly, Nancy Nichols, David Simonin
It has been common practice in data assimilation to treat observations errors as
uncorrelated; however, recent work has shown that the inter-channel observation error
statistics for certain satellite instruments exhibit a correlated structure. As a result
meteorological centers are beginning to use correlated inter-channel observation errors in
their operational assimilation systems. In this work we characterise both inter-channel and
spatial error correlations for observations from the Spinning Enhanced Visible and Infrared
Imager (SEVIRI). The errors are calculated using a diagnostic that makes use of statistical
averages of observation-minus-background and observation-minus-analysis residuals. The
results suggest that the operational variances are much too large, with the estimated
variances being as low as one tenth of those currently used. We find that the horizontal
observation error correlations range between 30km and 80km dependent on the observation
channel; this is larger than the operational thinning distance of 24km. The upper level water
channels have significantly correlated inter-channel errors, as do the surface channels. We
find, for the surface channels, that the observation error variances and inter-channel
correlations are larger in coastal areas of the domain. This is the result of mixed pixel
observations being assimilated.
Diagnosing observation error statistics for Doppler radar
radial wind observations
Joanne Waller, PDRA, University of Reading
Other Authors: Sarah Dance, Nancy Nichols, David Simonin
With the development of convection permitting numerical weather prediction, the efficient
use of high resolution observations, such as Doppler radar radial winds, in data assimilation
is becoming increasingly important. These observations are now routinely assimilated in
operational systems, though to avoid violating the assumption of uncorrelated observation
errors it is necessary to reduce the density of the observations both by the use of
superobservations and observation thinning. Taking into account the full, potentially
correlated, error statistics will allow the quantity of observations used to be increased and
may improve the impact that the observations have in the assimilation. In this work we use a
diagnostic that makes use of statistical averages of background and analysis innovations to
calculate observation error statistics for the Doppler radar radial winds that are assimilated
into the Met Office 1.5km model. Results show that the Doppler radar radial wind error
standard deviations are similar to those used operationally and increase as the height of the
observation increases. The observation correlation length scales found using the diagnostic
are larger than operational thinning distance of 6km and are dependent on both the height of
the observation and on the distance of the observation away from the radar. Additional tests
show that the long correlation length scale cannot be attributed to the background error
covariance matrix used in the assimilation. However, it is possible that the use of
superobservations or a simplified observation operator results in some of the large length
scale horizontal correlations.
Using methane isotopologues to constrain Arctic methane
emissions
Nicola Warwick, Research Associate, University of Cambridge,
NCAS
Other Authors: Michelle Cain, Rebecca Fisher, James France, David Lowry, Euan
Nisbet, John Pyle
Methane is an important greenhouse gas. The Arctic is a region of significant methane
emissions from both natural and anthropogenic sources. Arctic sources of methane include
wetlands, some of the World’s largest gas fields, decomposing gas hydrates and melting
permafrost. Many of these methane sources are poorly quantified and some have the
potential to lead to a positive climate feedback, releasing more methane as the climate
warms. Here we present global atmospheric model simulations of Arctic methane as part of
the NERC MAMM project (Methane and other greenhouse gas in the Arctic: Measurements,
Process Studies and Modelling). In our simulations, atmospheric methane is coloured by
source and δ13C and δD isotopic composition to determine the contributions of different
methane sources to the Arctic methane budget. Results from our simulations indicate a
different seasonal cycle for high northern latitude (>50°N) wetland emissions than predicted
by process model studies, which could impact the way top down studies apportion different
methane sources in the Northern Hemisphere. In our simulations, recent predictions of large
methane emissions from thawing submarine permafrost on the Arctic Shelf can only be
reconciled with global scale atmospheric observations by making large adjustments to high
latitude anthropogenic emission inventories.
Drivers for Seasonal Variability of Winter Storms over
Europe
Simon Wild, PhD Student, University of Birmingham, School of
Geography, Earth and Environmental Sciences
Other Authors: Daniel J Befort, Gregor Leckebusch
Winter storms associated with extreme wind speeds and heavy precipitation are the most
costly natural hazard in several European countries including the UK. Exceptional stormy
and rainy weather conditions in e.g. winter 2013-2014 and the ongoing winter 2015-16
caused major destructions primarily through flooding. Improved seasonal forecasts of winter
storms will thus help society, policy-makers and (re-) insurance industry to be better
prepared for such events. In this study we will investigate mechanisms and precursor
conditions (primarily over the North Atlantic) on a seasonal time scale leading to enhanced
winter storm frequency over Europe. Secondly we will analyse whether existing seasonal
forecast systems, namely the ECMWF S3 and S4 model suites, are able to capture these
identified links. We will show that an increased temperature gradient at the western edge of
the North Atlantic is related to winter storm frequency further downstream partly causing
increased numbers of storms over the British Isles, as e.g., in winter 2013-14. Further
sources of seasonal predictability over the North Atlantic include the 'Horseshoe Index', a
SST tripole anomaly pattern that - if present in the previous summer - could also cause a
higher number of winter storms over Europe. We will show results of AMIP-type sensitivity
experiments using a state-of-the-art AGCM (ECHAM5), supporting this hypothesis.
Connection of African Easterly Waves and Equatorial Waves
Gui-Ying Yang, Senior Research Fellow, NCAS-Climate, University
of Reading
Other Authors: John Methven and Steven Woolnough
Connection of African Easterly Waves and equatorial waves. Gui-Ying Yang, John Methven
and Steve Woolnough. National Centre for Atmospheric Science, UK. University of Reading,
Reading, UK. Envelopes of active convection are frequently observed to be related to the
structure of large-scale waves. Examples of such phenomena include African Easterly
Waves (AEWs) and equatorial waves which are fundamental components of the tropical
climate system. However, there are severe deficiencies in the simulation of the initiation,
amplitude and phase speeds of AEWs. Therefor identifying and understanding the
processes that are important in AEWs initiation, maintenance and propagation is important
for the improvement of weather forecasting in the tropics and is also likely to be crucial for
climate prediction. In this study, ERA-Interim data in the period 1979-2010 are used to
investigate the relationship of AEWs and equatorial waves in June-September. It is found
that a large portion of AEWs are connected to equatorial westward-moving mixed Rossby
gravity (WMRG) and n=1 and 2 Rossby (R1 and R2) waves, especially in the lower
troposphere. Some convection associated with AEWs tends to occur in the cyclonic centre
of R2 waves in the lower troposphere and the NH convergent (divergent) region of WMRG
waves in the lower (upper) troposphere. The crests and troughs of AEWs, tracked using low
level vorticity centres, move along with horizontal structures associated with these equatorial
waves. Composites relative to vorticity centres have a strong projection onto WMRG, R1 and
R2 waves. It is also found that the meridional wind component that projects onto R2 waves
tilts upshear below the African Easterly Jet which is a signature of baroclinic wave growth.
The wind projecting onto other wave modes is untilted or tilts downshear. It is suggested that
the structure of AEWs bears some resemblance in the horizontal to the structures from
equatorial wave theory.
The contrasting roles of water and dust in controlling daily
variations in radiative heating of the summertime Saharan
Heat Low
Cathryn Birch, Research Fellow, University of Leeds
Other Authors: Jamie Banks, Helen Brindley, Luis Garcia-Carreras, Douglas Parker,
Alex Roberts, Claire Ryder, Martin Todd
The summertime Sahara Heat Low (SHL) is a key component of the West African Monsoon
(WAM) system. Considerable uncertainty remains over the relative roles of water vapour and
dust aerosols in controlling the radiation budget over the Sahara and therefore our ability to
explain variability and trends in the SHL, and in turn, the WAM. Here, new observations from
the Fennec field campaign during June 2011 and June 2012, together with satellite retrievals
from GERB, are used to quantify how total column water vapour (TCWV) and dust aerosols
(from aerosol optical depth, AOD) control day-to-day variations in energy balance in both
observations and ECWMF reanalyses (ERA-I). The data show that the earth-atmosphere
system is radiatively heated in June 2011 and 2012. It is TCWV that largely determines
variations in daily mean TOA net flux and the net heating of the earth-atmosphere system. In
contrast, dust provides the primary control on surface heating, but the decreased surface
heating from dust is largely compensated by increased atmospheric heating, and so dust
control on net TOA radiation is weak. Dust and TCWV are both important for direct
atmospheric heating. ERA-I captures the control of TOA net flux by TCWV, with a positive
correlation (r=0.6) between observed and modelled TOA net radiation, despite the use of a
monthly dust climatology in ERA-I that cannot capture the daily variations in dustiness.
Variations in surface net radiation, and so the vertical profile of radiative heating, are not
captured in ERA-I, since it does not capture variations in dust. Results show that ventilation
of the SHL by cool moist air leads to a radiative warming, stabilising the SHL with respect to
such perturbations. It is known that models struggle to capture the advective moistening of
the SHL, especially that associated with mesoscale convective systems. Our results show
that the typical model errors in Saharan water vapour will lead to substantial errors in the
modelled TOA energy balance (tens of W m-2), which will lead to errors in both the SHL and
the WAM". i.e. W/m2
Impact of sub-kilometre model rainfall forecasts on UK
urban flood predictions
Cathryn Birch, University Academic Fellow, University of Leeds
Other Authors: Sophie Cowie, Kirsty Emma Hanley, Neil Hunter, Rob Lamb, Alex
Scott, Kay Shelton, Sarah Warren
In recent years there have been a number of summetime flood events within the UK that
have caused significant disruption and damage to buildings and infrastructure, with acute
damage in urban areas. In these events, the primary source of flood risk in urban areas is
surface water (or “pluvial”) flooding before rainwater has entered a watercourse. A
recommendation of the Pitt review, which followed the 2007 flood events, was to further
develop tools and techniques for predicting and modelling surface water flooding.
Urban flooding is the direct response to high-intensity, possibly sub-hourly, rainfall episodes,
which are often caused by convective storms in the summer months. Here we use regional
convection-permitting Met Office Unified Model simulations to study a case of summertime
heavy convective rainfal over the south-west of England. The simulations were performed as
part of the NERC-funded DYMECS project with grid-spacings of 1500, 500 and 200m for 7
August 2011, when more than 100mm of rain fell over the Bath and Taunton area.
The simulations are used to understand the impact of model resolution on flood prediction.
First the model simulations of rainfall are evaluated against radar and rain gauge data. The
observations and model simulations are then used to drive JFlow, a flood model that
produces high-resolution hazard mapping. Comparisons between the outputs from the flood
model give insight into whether the increased horizontal resolution of the rainfall input data is
of significant benefit for flood prediction.
Atmospheric Feedbacks in the ENSO cycle and the Role of
the Hydrological Cycle
Samantha Ferrett, Associate Research Fellow, Exeter University
Other Authors: Matthew Collins
In the context of shale gas exploration and production, atmospheric emissions have a
number of potential impacts. Emissions may (both separately and collectively) have
implications for climate change, air quality and public and occupational health. Public health
impacts concern direct primary emission from infrastructure on site (e.g. Particulate Matter
(PM) and nitrogen dioxide (NO2) from generators, traffic, plant, flares, dust and materials
handling), to gases that may affect air quality (e.g. Non methane hydrocarbons (NMHCs)),
as well as potentially hazardous and harmful trace gases (e.g. benzene). Secondary impacts
may occur downwind through reactive chemistry. There are numerous sources of
greenhouse gases — both natural and artificial. Natural variations of long-lived greenhouse
gases, mainly methane (CH4) and carbon dioxide (CO2), relate to soil and deeper subsurface processes. This signal is augmented by emissions from vehicle exhausts, industry
and landfill. Development of a shale gas exploration programme potentially adds further
fugitive emissions from leaks, gas storage, processing operations, frack fluid and flowback.
Wide variations in the concentration of these gases occur over various timescales as a result
of uptake by plants and variations in anthropogenic emissions. Variations can be seen for
even minor changes in wind direction, depending on local conditions (e.g. if a road exists
nearby). Monitoring of gases over time therefore provides an understanding of the baseline,
upon which any changes induced by future activity can be compared quantitatively. It is
important to establish the range of baseline concentrations of greenhouse gases and other
air quality parameters before any shale gas operations begin. The air quality measurement
site is based at Kirby Misperton inside the boundary of the Third Energy site situated there. It
comprises a waterproof enclosure containing instrumentation to measure continuous
concentrations of ozone (O3), PM, nitrogen oxides (NOx), CH4 and CO2 as well as
meteorological measurements (wind speed, wind direction, air temperature and relative
humidity). In addition to this air samples will be taken in stainless steel canisters and
returned to York for analysis of NMHCs.
Laboratory evidence supporting a hybrid model of black
carbon optical properties
James Allan, Senior Research Fellow / NCAS Scientist, University
of Manchester / NCAS Composition
Other Authors: M Rami Alfarra, Hugh Coe, Dantong Liu, Gordon McFiggans, James
Whitehead
It is established that atmospheric radiative properties, and thus climate and weather, are
highly sensitive to black carbon (BC) produced by combustion, particularly on regional
scales. However, the magnitude and in some cases even sign of this anthropogenic
perturbation remain uncertain. Part of this uncertainty is due to complications in our ability to
model its optical properties based on bottom-up composition and morphological data. An
aspect of this complicated nature is the effect of co-called ‘coatings’, i.e. non-BC material
that is co-emitted on the particles or is added through atmospheric processing. Typically,
diesel engines emit particles with thin coatings whereas biomass burning produces thickly
coated particles. Depending on the model used, it can be predicted that these coatings could
increase the mass absorption cross section of the BC by a factor of 2 or more, however,
data on this taken from field measurements has to date been seemingly contradictory. Here
we present laboratory data using a diesel engine and a novel combination of instruments
that supports the use of a hybrid model, whereby the optical enhancements only become
active once the coating mass fraction is above a certain amount. We hypothesise that this is
because that at lower mass fractions the coatings do not completely envelop the BC. This
has implications in how BC optical properties are handled in regional and global models.
Improved Soil Water Stress Representation in JULES Land
Surface Model and its Simulations of Vegetation Function
over Europe
Beena Balon Sarojini, Post doctoral Research Scientist, NCASClimate / University of Reading
Other Authors: Gregorio Egea, Anne Verhoef, Pier Luigi Vidale
Current land surface schemes in weather and climate models use coupled photosynthesis–
stomatal conductance (A–gs) sub-models of plant function to estimate plant transpiration,
which is part of the land surface energy, water and carbon fluxes. Plant function is controlled
by many environmental factors, and soil moisture control on root water uptake and stomatal
function is a primary control on feedbacks in sub-tropical to temperate ecosystems.
Parameterisations of the above process of soil moisture control on plant function (called soil
water stress or beta) vary among Land Surface Models (LSMs). We have implemented
higher levels of biophysical complexity in the state-of-the-art LSM, JULES, by allowing root
zone soil moisture to limit plant function non-linearly via individual routes of CO2 assimilation,
stomatal conductance, or mesophyll conductance as well as combinations thereof (Egea et
al. 2011 ; Verhoef & Egea, 2014). We show that simulations including stomatal and
mesophyll routes in the imposition of soil water stress on plants are better capable of
simulating the spatiotemporal variability in water use efficiency and can support more
versatile ecosystem responses, e.g. those observed in different regions that are radiation
limited or water limited. Our results have implications for simulating soil moisture,
evapotranspiration and soil-land-atmospheric interactions over the European region
including the UK.
Sensitivity analysis of a probabilistic road surface
temperature forecast model
Thomas Bennett, PhD Student, Aston University
The effective maintenance of road surfaces during winter months in extreme weather is
necessary to minimise accidents and ensure that traffic is kept moving. Decisions on
whether to salt the roads in a region have to be made daily. Road salt is expensive and
environmentally harmful so it should not be used when it is not needed; on the other hand if
it is not applied when it should be the roads will be more dangerous. It is therefore important
that an effective forecast model for the road surface is in place to aid these decisions. We
present results from our road surface temperature model which uses a surface energy
balance approach. The inputs include meteorological, physical and traffic parameters that all
have some uncertainty associated with them. The aim of the sensitivity analysis applied here
is to determine which of these input parameters have the largest effects on the output road
surface temperatures. The aim is then to highlight the parameters that have been shown to
be the most important, and where possible reduce our uncertainty about these through
measurement, so that the overall uncertainty of the model is reduced and more confidence
can be placed in the forecasts. We apply several different sensitivity studies, addressing
different aspects of the model behaviour. A traditional sensitivity analysis shows which
parameters the model is most sensitive to on average over all weather and input scenarios.
We also show results from forecast sensitivity analyses of the model run in an ensemble
prediction mode which show how the most important parameters can change depending on
the input and initial conditions of the model. Such sensitivity analyses are more useful for the
forecasting context, since in operational use, it is the forecast response that is most relevant.
The model forecast sensitivity is dominated by the forecast air temperature with wind speed,
relative humidity, sky view factor and road traffic volume also showing time varying
influence. Many parameters have little influence on the response of the ensemble mean
beyond finite sample (ensemble) size effects. We describe how the sensitivity analysis can
be used to identify areas of the model that would benefit from better observation, and
discuss how the results can be used to improve probabilistic road weather forecasting.
Valley heat deficit as a bulk measure of wintertime
particulate air pollution in the Arve River Valley
Charles Chemel, Research scientist, National Centre for
Atmospheric Science, University of Hertfordshire
Other Authors: Gabriele Arduini, Yann Largeron, Dominique Legain, Alexandre Paci,
Chantal Staquet, Diane Tzanos
Urbanized valleys are particularly vulnerable to particulate air pollution during the winter,
when ground-based stable layers or cold-air pools persist over the valley floor. We examine
whether the temporal variability of PM10 concentration in the section of the Arve River Valley
between Cluses and Servoz in the French Alps can be explained by the temporal variability
of the valley heat deficit, a bulk measure of atmospheric stability within the valley. We do this
on the basis of temperature profile and ground-based PM10 concentration data collected
during wintertime with a temporal resolution of one hour or finer, as part of the Passy-2015
field campaign conducted around Passy in this section of valley. The valley heat deficit was
highly correlated with PM10 concentration on a daily time scale. The hourly variability of
PM10 concentrations was more complex and cannot be explained solely by the hourly
variability of the valley heat deficit. The interplay of the diurnal cycles of emissions and local
dynamics is demonstrated and a drainage mechanism for observed nocturnal dilution of
near-surface PM10 concentrations is proposed.
On the role of subgrid turbulence models in the boundarylayer grey zone
Omduth Coceal, NCAS Research Scientist, University of Reading
(NCAS)
Forecasting localised weather conditions such as fog, poor air quality, high surface
temperatures and thunderstorms remains a significant challenge for NWP. A key part of the
challenge involves the representation of small scale processes, including turbulence in the
atmospheric boundary layer (particularly the stable boundary layer). High resolution NWP
promises to deliver better localised forecasts, but will increasingly rely on adapting existing
or developing new parametrisations to work in the so-called “grey zone” where boundarylayer turbulence and other small-scale processes are partially resolved. This study compares
several subgrid models using large-eddy simulations (LES), and evaluates their performance
as potential candidates for the grey-zone regime. Methods of anaylsis include comparing
sub-filter stress contributions from the models, turbulence statistics and organised structures
against results from high resolution LES.
Investigating the water balance in West Africa during wet
and dry years
Peter Cook, Research Scientist, NCAS-Climate, Department of
Meteorology, University of Reading
Other Authors: Emily Black, Anne Verhoef
Research is being carried out on modelling of the terrestrial water balance with land surface
models, in the context of recharge prediction of Sub-Saharan shallow aquifers. Emphasis is
on extremes in the recharge time series and how these may change in the future, in relation
to management of surface and groundwater resources in Sub-Saharan Africa (SSA). We are
currently using daily data of precipitation, surface and subsurface run-off, evapotranspiration and soil moisture from ERA-Interim/ERA-LAND reanalysis, and derived from an
ensemble of high resolution model runs (UPSCALE), for 1985-2010, to study the SSA water
balance. This work is part of the BRAVE research project, “Building understanding of climate
variability into planning of groundwater supplies from low storage aquifers in Africa - Second
Phase”, funded under the NERC/DFID/ESRG Unlocking the Potential of Groundwater for the
Poor (UPGro) Program. Investigators are from the Departments of Meteorology and of
Geography and Environmental Science at the University of Reading, the British Geological
Survey, and a large number of water resources research, governance, and (international) aid
agency partners in Ghana and Burkina Faso.
Evaluation of the upper-level circulation in the TibetanPlateau region in the Met Office Unified Model
Julia Curio, Post-doctoral research scientist, NCAS-Climate and
Department of Meteorology, University of Reading
Other Authors: Andrew Turner, Reinhard Schiemann
The Tibetan Plateau (TP) plays an important role in global atmospheric dynamics and in
shaping the regional atmospheric circulation over South and East Asia. Modelling the
atmospheric flow over and around the TP is a particular challenge due to the complex
interactions between mechanical and thermal forcing by topography and the location of the
TP between the Asian monsoon and mid-latitude westerlies.
The upper-tropospheric Asian Westerly Jet (AWJ; including its East Asian Subtropical and
Polar-front components) is a convenient indicator of the regional circulation as a whole and
plays an important dynamical role in downstream surface conditions and circulation, for
example for the seasonal evolution of precipitation regimes over China. Despite the
importance of the AWJ, detailed evaluations of the AWJ in global circulation models (GCMs),
including in the Met Office Unified Model (MetUM) are rare.
The work in this study forms part of the new Climate Science for Services Partnership
(CSSP) China on the Tibetan Plateau. We evaluate the representation of the AWJ including
its seasonal migration between the south and north sides of the TP in the MetUM. We
develop metrics to capture monthly-mean as well as transient properties of the AWJ on
synoptic timescales. These metrics are applied to recent high-resolution MetUM simulations
developed in the FEBBRAIO and PRIMAVERA projects, and to verifying atmospheric
reanalysis data. Statistical relationships between the AWJ and surface temperature and
precipitation over the TP and downstream will be also be determined in the MetUM and in
reanalysis data/observations.
Changes in Arctic summer cyclone behaviour during the
21st Century
Jonny Day, AXA Research Fellow, University of Reading
Other Authors: Giuseppe Zappa
Unlike the mid-latitude storm tracks of the North Atlantic and Pacific, which are most active
during winter, Arctic synoptic scale cyclones and extreme winds are more frequent during
summer. The dramatic warming of the Arctic over the last three decades has reduced both
the thickness and area covered by summer sea ice, leaving Arctic waters navigable by ship
traffic exactly during this period of seasonally enhanced cyclone activity. The understandable
desire of the international shipping industry to utilise opportunities offered by Arctic
navigation has led to a 10-fold increase in Arctic marine traffic on the Northern Sea Route.
However, according to a recent report by Lloyds of London “the risks involved are not
understood at a level to enable underwriters to price insurance for Arctic transit with either
clarity or certainty”. This study will present an assessment of the performance of CMIP5
models in representing Arctic summer cyclone frequency and intensity during the last 30
years and present results on how these properties will change in the future.
A novel multispectral algorithm based on the Meteosat
Second Generation satellite for the detection, tracking and
nowcasting of the thunderstorms
Michele de Rosa, Weather systems analyst/Researcher, Geo-K S.r.l.
Other Authors: Fabio Del Frate, Matteo Picchiani, Massimiliano Sist
The number of the extreme meteorological events has increased in the last few years and
the trend should be the same for the next future. The development of these events is very
short both in time and space and the damages could be very huge in terms of human life
losses. So it is very important to monitor and prevent these natural hazards by means of
advanced techniques which are able to: detect the event as soon as possible; track the
behavior of the event and predict the development of the event. The aim of this work is to
present a new algorithm, named StormTrack, based on the Meteosat Second Generation
(MSG) satellite. The StomTrack algorithm is able to use several channels of the MSG for the
early detection, the tracking and the nowcasting of the stormy objects. The detector makes
use of the two water vapor channels together with the 10.8 𝜇m channel in order to detect the
base (channel 6 and channel 9) and the nuclei (channel 5 and channel 9) of the cells without
any threshold. In this step some features, like the geometry and the level of hazard, are
extracted. The detected objects are tracked, using a temporal correlation, and their
trajectories are computed together with the phase of each detected cell. This step makes
use of some algorithms from the computational geometry. The final step is the nowcasting of
the detected cells. Each object is projected ahead in order to predict its development both in
space and time. The prediction interval ranges from 15 minutes to 30 minutes ahead. Some
results on selected case studies are presented together with the comparison with similar
algorithms.
Exploring the diabatic role of ice microphysical processes
in two North Atlantic summer cyclones
Dr Chris Dearden, Post-doctoral Research Fellow, University of
Manchester
Other Authors: Jen-Ping Chen, Tzuchin Tsai, Geraint Vaughan
Numerical simulations are performed with the Weather Research and Forecasting model to
elucidate the diabatic effects of ice phase microphysical processes on the dynamics of two
slow moving summer cyclones that affected the UK during the summer of 2012. The first
case is rep resentative of a typical mid-latitude storm for the time of year, whilst the second
case is unusually deep. Sensitivity tests are performed with 5 km horizontal grid spacing and
at lead-times between 1-2 days using three different microphysics schemes, one of which is
a new scheme whose development was informed by the latest in-situ observations of midlatitude weather systems. The effects of latent heating and cooling associated with
deposition growth, sublimation and melting of ice are assessed in terms of the impact on
both the synoptic scale and the frontal scale. The results show that, of these diabatic
processes, deposition growth was the most important in both cases, affecting the depth and
position of each of the low pressure systems and influencing the spatial distribution of the
frontal precipitation. Cooling associated with sublimation and melting also played a role in
determining the cyclone depth, but mainly in the more intense cyclone case. We also explore
the effects of ice crystal habit and secondary ice production in our simulations, based on
insight from in-situ observations. However in these two cases, the ability to predict changes
in crystal habit did not significantly impact the storm evolution, and we found no obvious
need to parameterize secondary ice crystal production at the model resolutions considered.
A 3D NCAS community Chemical Transport Model:
Convective tracer transport and other applications
Wuhu Feng
Other Authors: Martyn Chipperfield, Sandip Dhomse, Ryan Hossaini
TOMCAT is a 3D chemical transport model (www.see.leeds.ac.uk/tomcat). It contains a
detailed description of stratospheric and tropospheric chemistry. TOMCAT is also the host
CTM for the GLOMAP global aerosol model. TOMCAT is a test-bed for development of
aerosol and chemistry schemes for the UM and UKCA. It shares common chemistry /
aerosol code. Since mid 2011 NCAS has been supporting the development of
TOMCAT/SLIMCAT in Leeds through the co-funding of Wuhu Feng. The model is currently
being used in a wide variety of scientific studies and has been available for the UK
researchers. In the poster, we will show some model applications including the issues
related to the treatment of convective tracer transport and as well as the quality of
meteorological analysis data used in the model.
Perturbation Growth Structure in Different Convective
Regimes
David Flack, PhD Student, University of Reading
Other Authors: George Clinton Craig, Suzanne Gray, Humphrey William Lean,
Robert Plant
Convection-permitting ensembles have led to greater understanding of the variability of
convective-scale forecasts. However, convective-scale variability is not fully understood,
especially with respect to different convective regimes. Using a convective adjustment
timescale to diagnose the convective regimes of quasi-equilibrium and non-equilibrium, four
convective cases are examined in convection-permitting ensembles. The ensembles (6
perturbed members, 1 control member) are based on the operational United Kindom
Variable resolution (UKV) configuration of the Met Office Unified Model and Gaussian
peturbations are added into the boundary layer to represent turbulent fluctuations close to
the model grid scale. Regime differences are highlighted in the vertical and horizontal
structure of the perturbation growth. Further understanding of perturbation growth within the
different regimes could lead to better understanding of convective-scale variability.
Predicting high-impact freezing rain events in the ECMWF
global model
Richard Forbes, Senior Scientist, ECMWF
Other Authors: Timothy Hewson, Ivan Tsonevsky
Freezing rain is a weather hazard with potentially severe consequences for transport, power
loss, damage to infrastructure, vegetation and a danger to lives. It is therefore an important
weather phenomenon for operational numerical weather prediction models to be able to
forecast. A recent change to the operational global model at the European Centre for
Medium-Range Weather Forecasts has significantly improved the prediction of freezing rain.
Forecasts for European and North American case studies illustrate the potential for providing
useful information on severe freezing rain events a few days in advance. A statistical
evaluation over the last decade of winter seasons highlights the regions most affected by
freezing rain.
Impact of different convection permitting resolutions on
the representation of heavy rainfall over the UK
Giorgia Fosser, Regional Climate Change Scientist, Met Office
Hadley Centre
Other Authors: Steven Chan, Elizabeth Kendon
Deep convection is responsible for some of the most damaging weather phenomena (e.g.
heavy rainfall, large hail, and tornadoes) and acts on an hourly time scale over a spatial
scale of few kilometres. To represent the average effects of convection, global and regional
climate models (with grid spacings of order 10-100 km) rely on parameterisation schemes.
These are a known source of model deficiencies, leading to errors in the diurnal cycle of
summer precipitation and an underestimation of hourly precipitation extremes. Higher
resolution regional climate models (<10km grid spacing) that give a better representation of
the effects of mountains and coastlines, and mesoscale dynamics, are increasingly
becoming available. As grid spacings approach the km-scale, the so-called “convection
permitting” scale, it is possible to represent deep convection explicitly. Previous studies (e.g.
Ban et al, 2015; Fosser et al, 2015; Kendon et al, 2015) have show that these convection
permitting models are able to give a much more realistic representation of convection, and
are needed to provide reliable projections of future changes in hourly precipitation extremes.
In this context, the UKCP18 project aims to provide policy makers with new UK climate
change projections at hourly and local scales, thanks to the first ensemble of runs at
convection permitting resolution. This study outlines the benefits of convection-permitting
resolution in terms of the representation of heavy rainfall, and investigates the impacts of
different convection permitting resolutions as well as the domain size. Bibliography Ban N,
Schmidli J, Schaumlr C (2015) Heavy precipitation in a changing climate: Does short-term
summer precipitation increase faster? Geophys Res Lett 42-1172. Fosser G, Khodayar S,
Berg P (2015) Benefit of convection permitting climate model simulations in the
representation of convective precipitation. Kendon EJ, Roberts NM, Fowler HJ, et al (2014)
Heavier summer downpours with climate change revealed by weather forecast resolution
model. Nat Clim Chang 4:570-576.
Hybrid parallelization and domain nesting in the ELMM
LES code
Vladimír Fuka, Research Fellow, University of Southampton,
Aerodynamics and Flight Mechanics
This paper presents first results of project “Large-Eddy Simulation Code for City Scale
Environments” funded by ARCHER eCSE. The project aims to enhance the capabilities of
the LES model ELMM (Extended Large-eddy Microscale Model) for simulations of city scale
areas (<10 km)) while achieving high resolution within street canyons in certain areas of
interest. Two main steps for this objective are hybrid OpenMP/MPI parallelization for better
parallel efficiency with very large numbers of processors and domain nesting to achieve
higher grid resolution in selected areas. The main reason why hybrid parallelization was
selected was the usage of the fast Fourier transform for the solution of Poisson equation
during pressure correction. This step becomes a major factor determining the length of the
solution when large number of processors is used. Domains are implemented in ELMM as
sets of MPI processes which communicate with each other as in a normal non-nested run,
but also with processes from another (inner/outer) domain. It should stressed that the
duration of solution of time-steps in the outer and in the inner domain must be synchronized,
so that the processes do not have to wait for the completion of their boundary conditions.
This can achieved by assigning an appropriate number of CPUs to each domain, and to gain
high efficiency. When nesting is applied for large eddy simulation, the inner domain receives
inflow boundary conditions which lack turbulent motions not represented by the outer grid.
ELMM remedies this by optional adding of turbulent fluctuations to the inflow using the
efficient method of Xie and Castro (2008). The spatial scale of these fluctuations is in the
subgrid-scale of the outer grid and their intensity will be estimated from the subgrid turbulent
kinetic energy in the outer grid. The developed ELMM code is accessible by the Archer
community.
The introduction of automatic nowcasting warnings for
thunderstorms at MeteoSwiss
Marco Gaia, Head of the regional center south of MeteoSwiss,
MeteoSwiss
Thunderstorm warnings are a high priority task for national weather services, because of the
serious damages caused by flash floods, heavy precipitations, strong wind gusts, hail or
lightning. MeteoSwiss, the national weather service of Switzerland, has recently developed a
novel automatic thunderstorm warning system based on the algorithm called “TRT”
(Thunderstorms Radar Tracking).
The main use of TRT is the early identification of thunderstorm cells and the retrieval of the
most critical parameters such as cell extension, velocity, direction and vertical development,
thanks to real-time weather radar observations. Based on the TRT information, the new
automatic thunderstorm warning system derives the motion and intensities of the
thunderstorm cells. After extrapolating the future position of each cell in the next minutes (up
to 30 min) a notification informing about the location, the intensity and the lead-time of the
convective cell can automatically be introduced in the operational warning system used by
the forecaster office to issue the thunderstorm warnings.
The aim is to support the overall warning system of MeteoSwiss for the thunderstorms. Until
now, indeed, the thunderstorm warnings are sent out manually by the forecaster for one of
the 159 warning regions of Switzerland. In very intense convective situations, with a lot of
thunderstorm cells, the limits of this manual approach are soon achieved. During the
summer seasons 2014 and 2015, MeteoSwiss has launched two test campaigns in order to
evaluate the performance of the new automatic system. This comparison was performed at
the level of the 159 warning regions. From the results it emerges that the overall
performance of the automatic system was comparable with the performance of the manual
system, with both POD of about 30% and FAR of 60%. But the automatic system was able
to send out the warnings 14-18 minutes before the manual warning system. This is a very
significant improvement for nowcasting thunderstorm warnings.; as expected the automatic
system is able to reduce the “emission time”. Moreover the automatic warning system opens
new possibilities to alert the population through mobile telecommunication devices.
The tool allows a user to receive thunderstorm information for a given location directly and
automatically on his phone and/or e-mail box whenever the system detects an incoming
thunderstorm cell for his location. During the summer seasons 2014 and 2015, MeteoSwiss
has launched two test campaigns with more than 500 beta testers. The results of the both
test campaign have been very promising. With a POD (Probability Of Detection) of 77% in
2014 and 88% in 2015, and a FAR (False Alarm Ratio) of 23% in 2014 and 33% in 2015, the
beta testers’ feedbacks reported a quite encouraging scenario from the users’ point of view.
Finally, users showed general satisfaction for the new automatic system and they
appreciated the opportunities offered by such systems (e.g. customization). Especially the
possibility to get thunderstorm warnings for given location, defined by geographical
coordinates, has been appreciated.
On the basis of this results MeteoSwiss is planning to introduce officially the automatic
warning for thunderstorms starting in summer 2016. At the conference in Manchester we will
explain not only how the automatic systems works and the results of the test campaigns, but
we will illustrate as well how we will integrate the automatic system in the general activities
of the forecaster office. Indeed, even if the system can run fully automatic, we have
introduced the possibility for the forecaster to interact with the system, in order - for example
- to issue a manual warning, if the system is not able to detect a thunderstorms cell. In the
realization of the project, the “human side” (i.e. the interaction with the forecasters and the
inclusion of the customer’s needs in the process of the development) was as important as
the “hard side” of the system (i.e. the development of the scientific algorithm).
A winter case of a subsynoptic Mediterranean cyclone that
produced high impact weather
Ana Genoves Terol, PhD student, Department of Physics.
Universitat de les Illes Balears
On last February the 15th, 2016 a windy and heavy rain storm happened over the sea,on the
SW edge of the Mediterranean.
The high impact weather was related to the presence of a meso-cyclone that propagated
over the sea, south of the Balearics and northern of the Algerian coast. Some coastal places
at the south and southeast coasts of Iberia and the Islands (the Balearics and South of
Sardinia), were affected by strong winds and some heavy rain. The genesis of the cyclone at
sea level was around the Balearics, or east of the islands.
These kind of subsynoptic structures are not unusual in the Mediterranean sea. From time to
time the presence of heavy rain and strong winds are related to the presence of cyclones
developed only at low levels in the troposphere. The convergence produced by the presence
of the cyclone in cases of weak (or apparently indiferent) forcing at high levels, or the only
presence of a not large maximum wind at 300 hPa is enough to produce vertical velocities
and heavy rain. The life cycle of these mesocyclones can have a duration of some hours.
The area where the strong winds storm developed and its most notorious displacement
occurred (northern of Africa’s north coast) is known as an area of maximum presence of
cyclones, frequently associated with the topographic interaction of the flow from SSW with
the major Atlas mountain range. However, these kind of topographic structures are normally
stationaries, with exception of cases of high baroclinity at low levels and a PV maximum
arrives to the area where the surface cyclone is. In those cases a large scale mediterranean
storm can be produced. The episode of last February has some differences with the known
climatological behaviour for this area of the Western Mediterranean.
The event occurred when the ECMWF new-cycle 41r2 was in Beta testing - Release
Candidate testing mode, less than a month before the date of planned implementation (8
March 2016). The new high resolution and the new products related to convection can be an
excellent opportunity for understanding and forecasting the small scale processes that
happen in the Mediterranean or some other maritime areas of the world in relation to
subsynoptic cyclones heavy rain and strong winds.
A first study of this high impact weather event and the particular meteorological
circumstances are presented in this poster.
WMO/WWRP HIWeather project to harness global science
for better local warning systems
Brian Golding, Fellow in Weather Impacts, Met Office
Other Authors: David Johnston, Paolo Ruti
Early warning systems play a key role in enabling communities to survive and recover from
weather-related disasters. In the last decade, weather forecasting research has advanced to
support warning systems at longer lead times and smaller space scales, enabling protective
actions to be taken against a wide range of weather-related hazards. Building on these
developments, the World Meteorological organisation (WMO) World Weather Research
Programme (WWRP) launched the 10-year HIWeather project in January 2015 with the aim
of focussing international research on the further advances needed to optimise the
production and communication of hazard warnings. The poster will describe the scope of the
project, encompassing warnings of flooding, strong winds, wildfires, winter weather, extreme
heat and pollution, particularly focussing on the needs of megacities in the develolpoing
world. It will outline plans and progress under five research themes: growing knowledge of
the physical processes that lead to hazards, building better hazard prediction models;
modelling human impacts of hazards; developing good practice in communicating warnings;
evaluating forecasts and warnings. It willdescribe pans for capacity building through
Forecast Demonstration Projects, which integrate and trial the research outcomes in
collaboration with local National Meteorolgical & Hydrological Services, academic institutes
and users.
Verification of extreme rainfall using site-specific
climatology
Brian Golding, Fellow in Weather Impacts and Co-chair WMO
HIWeather project, Met Office
Other Authors: Clare Bysouth, Rebecca Stretton
This poster examines how well the probabilistic version of the site-specific forecasts that
appear on the Met Office web-site predict extreme 24h rainfall events. An analysis of the
climatology at every UK observing station reveals that choosing a single rainfall
accumulation threshold is inappropriate because one threshold may almost never be
exceeded at some locations but regularly exceeded at others; so the performance would be
dominated by the wettest sites in the UK. Therefore, in an attempt to forge a link between an
event and its impact we have chosen site-specific event thresholds that are based on the
climatology at each site (these have been calculated using 30 years of data at every
observing station). We have selected the 98.9th percentile of the climatology distribution at
each site (which corresponds to the four wettest days of the year) to obtain site-specific
event thresholds. For this analysis we have examined 21 months of 24h rainfall
accumulation forecasts at 128 sites using three verification methodologies; the Symmetric
Extremal Dependency Index, a threshold weighted version of the continuous ranked
probability skill score (CRPSS) and a partitioned version of the CRPSS.
11-yr Solar Cycle Influence on Atlantic / European Weather
Lesley Gray, NCAS Senior Scientist, Oxford University
Other Authors: Martin Andrews, Jeff Knight, Tim James Woollings
An 11-yr solar cycle influence on european weather has been postulated for many years but
evidence is weak and the signal is not statistically significant when observations such as
mean sea level pressure (mslp) and sea surface temperatures (SSTs) are correlated with an
11-yr solar index such as sunspot number. However, recent analysis of the Hadley Centre
December-January-February (DJF) mslp (HadSLP2) and SST (HadISST) datasets for 18702010 has shown evidence of a lagged response of mslp and SSTs, peaking at approximately
3-4 years after solar min/max. This has been further confirmed in a reconstructed dataset of
Atlantic / European sector mslp extending back to 1660. A mechanism for this lag has been
proposed that involves both atmospheric forcing via anomalies in stratospheric ozone and
temperatures together with an indirect forcing mechanism via Atlantic SST anomalies that
can persist beneath the mixed-layer during summer and re-emerge in the following winter,
thus amplifying and extending the signal from one year to the next. The nature of the 11-yr
signal is further explored in the HadSLP2 dataset by examining not only DJF averages but
also the individual months. This shows evidence for both of these mechanisms, and
suggests that the stratospheric mechanism dominates in late winter and the Atlantic SST
mechanism dominates in early winter. The 11-yr solar signal in frequency of Atlantic /
European blocking events is also investigated. The DJF signal is dominated by the late
winter response and maximises at lag-zero, suggesting an important role for stratospheric
influence on blocking.
Contribution of Tropical Cyclone to rainfall and moisture
transport over East Asia
Dr Liang Guo, University of Reading
Months from July to October are active TC season over EA with September has the most
TC. The seasonal cycles of northward and westward TC are different, with the number of
northward TC peaks at September and westward TC peaks at October. There are
discernible inter-annual and inter-decadal variabilities in the detected TC tracks. TC
contributes to 10-30% of overall rainfall along the coastal region of EA during JASO. During
its peak, its contribution can be up to 40% over South China and reaches as north as the
Korean Peninsula. The contribution of TC rainfall to extreme rainfall is higher and is up to as
large as 50-60%. As its contribution to extreme rainfall amount is larger than its contribution
to extreme rainfall days, TC rainfall is an important contributor to the most extreme daily
rainfall over EA. Though moisture transported by TC is smaller than mean EA summer
monsoon flow, due to different seasonal cycles between mean monsoon flow and TC
activity, moisture transported by TC eddy is important when EA summer monsoon shifts and
withdraws. In particular, when the monsoonal convergent band shifts to mid-latitude in July,
TC eddy becomes the moisture supplier over the south China; when EA summer monsoon
withdraws in September and October, TC eddy becomes the main moisture supplier over
EA, and its impact can be observed further inland. With further looking into the moisture
transport through the east and south boundaries along the EA coast, more differences
between the mean flow and TC eddy are revealed. For mean flow, moisture is gained via
the south boundary but is lost via the east boundary during the EA summer monsoon
season. For TC eddy, the situation is opposite, with moisture is gained via the east
boundary but is lost via the south boundary during the TC active season. The east boundary
moisture gaining is attributed to the layout between the direction of TC advance and the
direction of TC moisture flux. It is the moisture influx along the righthand side of the
westward TCs that contribute to this gaining. And the south boundary moisture losing is
attributed to the reversion of the mean specific humidity field.
Local and remote impacts of aerosol species on Indian
summer monsoon rainfall in a GCM
Liang Guo, University of Reading
The HadGEM2 AGCM is used to determine the most important anthropogenic aerosols in
the Indian monsoon using experiments in which observed trends in individual aerosol
species are imposed. Sulphur dioxide (SD) emissions are shown to impact rainfall more
strongly than black carbon (BC) aerosols, causing reduced rainfall especially over northern
India. Significant perturbations due to BC are not noted until its emissions are scaled up in a
sensitivity test, in which rainfall increases over northern India as a result of the Elevated
Heat Pump mechanism, enhancing convection during the pre-monsoon and bringing forward
the monsoon onset. Secondly, the impact of anthropogenic aerosols is compared to that of
increasing greenhouse-gas concentrations and observed sea-surface temperature (SST)
warming. The tropospheric temperature gradient driving the monsoon shows weakening
when forced by either SD or imposed SST trends. However the observed SST trend is
dominated by warming in the deep tropics; when the component of SST trend related to
aerosol emissions is removed, further warming is found in the extratropical northern
hemisphere that tends to offset monsoon weakening. This suggests caution is needed when
using SST forcing as a proxy for greenhouse warming. Finally, aerosol emissions are
decomposed into those from the Indian region and those elsewhere, in pairs of experiments
with SD and BC. Both local and remote aerosol emissions are found to lead to rainfall
changes over India; for SD, remote aerosols contribute around 75% of the rainfall decrease
over India, while for BC the remote forcing is even more dominant.
Wind-Tunnel simulation of stable atmospheric boundary
layers for fundamental studies in dispersion and wind
power
Paul Hayden, NCAS-Surrey PDRA, EnFlo Laboratory,
University of Surrey
Other Authors: Philip Hancock
In simple terms a stable atmospheric boundary layer is straightforward; it is one of rising
potential temperature with height. In practice, it is far from straight forward. As noted by
Hunt’s (1985) question: “is the structure of the stable boundary layer too variable to rely
upon?”. Nevertheless, understanding the behaviour of stable boundary layers, which are
very different from convective layers, is important for the understanding of surface transfers
of momentum, heat and substance, of the dispersion of contaminants or hazardous
substances, and of the development of the wakes of turbines in a wind farm. The latter
determines the energy output and loads on downwind machines (Hancock & Pascheke,
2014a, b). Recently we have been investigating artificially thickened (spatially evolving)
stable boundary layers, artificial thickening effectively making the EnFlo wind tunnel much
longer than it is in order to match the scale of the simulated boundary layer to the scale of
the model in question, such at a building or model wind turbine, and associated
instrumentation. This is being approached as a systematic study, referenced to a naturally
(but less deep) stable boundary layer, which is in the same range of boundary-layer-depthto-surface-Obukhov-length as a function of Richardson number. At this stage we are
confining our investigation to weak and moderately stable flow. So far the results show that
artificially thickened layers can be developed with characteristics that are near to but not
precisely the same as in a naturally growing layer. It appears that the discrepancy is
associated with the initial development of a stable layer. For a flow evolving spatially from
near-zero thickness as arises in a wind tunnel simulation, the flow is initially neutral, stability
increasing with increasing development length. Initial attempts at conditioning the inlet
temperature profile Tz, which had been successful for convective flows (Hancock et al.
2013), were a failure. It is interesting to note that a similar behaviour was observed by
Mason and Derbyshire (1990) in large eddy simulations of temporally evolving stable flow.
The work is still in progress; the contribution to the conference will include work yet to be
undertaken. Hunt, J C R (1985) Diffusion of the stably stratified atmospheric boundary layer.
J. Climate and App Meteorology, 24, 1187-1195. Mason, P J and Derbyshire S H (1990)
Large-eddy simulation of the stably-stratified atmospheric boundary layer. Boundary-Layer
Met., 53, 117-162. Hancock, P E and Pasheke, F (2014a, b) Wind-tunnel simulation of the
wake of a large wind turbine in a stable boundary layer. Part 1: the boundary layer
simulation. Part 2: the wake flow. Boundary-Layer Met. 151(1), 3-21; 23-37. Hancock, P E,
Hayden P and Zhang, S. 2013 A wind-tunnel artificially-thickened weakly-unstable
atmospheric boundary layer. Boundary-Layer Met. 149(3):355–380. Not sure which theme,
so have elected N/A assuming this is 'other'.
Rossby wave propagation on potential vorticity fronts with
finite width
Ben Harvey, Research Scientist, NCAS / University of Reading
Other Authors: Maarten Ambaum, John Methven
The horizontal gradient of potential vorticity (PV) across the tropopause typically declines
with lead time in global numerical weather forecasts and tends towards a steady value
dependent on model resolution. Rossby waves reside on and propagate along on this “PV
front”, and an accurate representation of their characteristics is crucial for weather forecasts.
This poster examines how the propagation of Rossby waves is affected by spreading the
tropopause PV contrast over a broader frontal zone. The approach taken is to analyse
Rossby waves on a PV front of finite width in a simple single-layer model. Broadening the
front causes a decrease in both the jet speed and the ability of waves to propagate
upstream. The contribution of these changes to Rossby wave phase speeds cancel at
leading order. At second order the decrease in jet speed dominates, meaning phase speeds
are slower on broader PV fronts. Estimates are made for the error in Rossby wave
propagation speeds due to the PV gradient error present in numerical weather forecast
models.
The representation of an observed cold front in a high
resolution NWP model
Ben Harvey, Research Scientist, NCAS / University of Reading
Other Authors: Chloe Eagle, Humphrey Lean, John Methven
This study assesses the representation of an intense cold front in high-resolution (<1km)
NWP simulations. The case used is from 24 November 2009 when an area of deep low
pressure developed to the west of Scotland and the associated trailing cold front advanced
from the west towards the UK and France. A unique in-situ observation dataset is available
for this case, provided by the FAAM BAe136J research aircraft. A low-level frontal circuit
was performed allowing accurate calculation of both the frontal circulations and the nearsurface turbulent fluxes. The focus of the study is the convergence of the model at high
resolution. Do the resolved frontal circulations vary with resolution, does the sharpness of
the frontal zone converge at high resolution, and is there a consistent transition from
parametrised to resolved turbulent fluxes as more of the boundary-layer structure is
resolved?
Reducing the risk of volcanic ash to aviation
Natalie Harvey, Research Scientist, University of Reading/NCAS
Other Authors: Helen Frances Dacre, Nathan Huntley, David Thomson, Helen
Webster
The ash produced when a volcano erupts provides a significant risk to aircraft through
temporary engine failure, permanent engine damage and visibility reduction. This risk is
avoided by closing airspace and re-routing flights, both of which have financial implications
for the aviation industry.
The RACER (Robust Assessment and Communication of Environmental Risk) project aims
to quantify the importance of the source, structural and parameter uncertainty in volcanic ash
forecasts. Volcanic Ash Transport and Dispersion models (VATDs) are complex and
therefore it is not possible to perform the large number of simulations needed to sample the
full range of parameter values. We can however use an emulator, a simple statistical
approximation of a complex model, to predict VATD output at any parameter choices given a
set of training simulations which span the all parts of parameter space. This enables the
whole of parameter space to be explored more quickly.
In this presentation, emulation of the Numerical Atmospheric-dispersion Modelling
Environment (NAME) model for a case study day in May 2010 will be discussed. This
emulator has been built using over 500 NAME runs. Each run has 27 parameters perturbed
including parameters relating to the eruption (e.g. plume height, particle size distribution and
ash density) as well as internal model parameters relating to turbulence and wet and dry
deposition. The perturbed parameter values are determined using Latin hypercube sampling
of ranges found through an expert elicitation process.
Through the development of this emulator it has been possible to identify the parameters
which contribute the largest uncertainty to the forecasts and thus identify priority areas for
model development and for observational campaigns. The emulator can also be used to
produce probabilistic forecasts of volcanic ash. This methodology could be easily transferred
to other dispersion applications.
Past and future emergence of climate extremes
Ed Hawkins, Associate Professor, NCAS-Climate, University of
Reading
Other Authors: Erich Fischer, Andrew King
Determining the time of emergence of climates altered from their natural state by
anthropogenic influences can help inform the development of adaptation and mitigation
strategies to climate change. Here we explore the past emergence of climate extremes and
find that we expect local temperature and precipitation extremes to already differ significantly
from their previous quasi-natural state at many locations or to do so in the near future. In
addition, agreement is high on the spatial pattern of long-term future forced heavy
precipitation response, which shows an intensification over most land regions, in particular
Eurasia and North America.
MAGIC - Managing Air for Green Inner Cities
Paul Hayden, Research Fellow, University of Surrey
Other Authors: Paul Linden, Chris Pain
MAGIC, the winner of the EPSRC Grand Challenge 2: Future Cities: engineering
approaches that restore the balance between engineered and natural systems, commenced
in December, 2015. It addresses the specific challenge: how to develop cities with no air
pollution and no heat-island effect by 2050? The project will develop a novel facility
consisting of an integrated suite of advanced models and an associated management and
decision support system that together allow the city design and its operation to manage the
air so that it becomes its own ventilation and cooling system, with clean, cool air providing
low-energy solutions for health and comfort. The facility comprises three key components: (i)
a fully resolved air quality model that interacts with sensor data and provides detailed
calculations of the air flow, pollutant and temperature distributions in complex city
geometries and is fully coupled to naturally ventilated buildings, and green and blue spaces;
(ii) reduced order models that allow rapid calculations for real time analysis and emergency
response; and (iii) a cost-benefit model to assess the economic, social and environmental
viability of options and decision. The scientific air quality component is a fully-resolved
computational model that couples external and internal flows in naturally ventilated buildings
at the building, block and borough scales. It will be supported and validated by field
measurements at selected sites and by wind tunnel and other laboratory studies. The
reduced order models will be developed from the computational model and from laboratory
process studies, and will be capable of producing gross features such as mean pollutant
concentrations and temperatures. They will be used to provide capabilities for scoping
studies, and real-time and emergency response. The cost-benefit model will provide the link
between the scientific and engineering models and implementation advice. It will include
modules for the built environment, public spaces and transportation, and provide estimates
of the life-cycle costs and benefits of the various scenarios at the individual building, city
block and borough scales. Eventually, it is envisaged that this will also include social and
health effects.
Forced Modes of winter Variability in GLOSEA5 seasonal
forecasts
Dan Hodson
Other Authors: Adam Arthur Scaife, Timothy Rowan Sutton
The GLOSEA5 seasonal forecast system exhibits a significant level of skill in predicting the
North Atlantic Oscillation and key aspects of European winter climate. Whilst GLOSEA5
reproduces the observed variability, the predictable signal appears to be weaker than that in
observations. Here we use an Optimal Detection methodology to examine the variability in
Mean Sea Level Pressure that is common across all members of the GLOSEA5 Winter
Forecast ensemble: the atmospheric forced modes driven by boundary forcing and initial
conditions. We find that dominant Forced Modes are an NAO-like dipole pattern and a PNAlike pattern. The latter is associated with an El Niño SST pattern in the ocean. The NAO-like
dipole is not strongly associated with any clear SST pattern, suggesting that it may arise as
a response to common atmosphere initial conditions, perhaps in the stratosphere, or some
other source of external forcing. The dominance of either Forced mode varies across the
winter months, with the NAO perhaps more dominant in early winter. Similar patterns are
seen in the observations, but the amplitudes are about three times larger than in the model,
generally consistent with previous results. The NAO-like pattern appears to dominate
preferentially in winters with fewer Sudden Stratospheric Warmings. We discuss these
results and examine the possible implications for seasonal forecasts of European winter
climate.
Importance of multiple cells in the 3 August COPE
potential flash-flood case
Yahui Huang
Other Authors: Alan Blyth
The COnvective Precipitation Experiment (COPE) field campaign took place over the south
west of England in the summer, 2013. The aim of the COPE is to understand the
microphysics and dynamics of convective clouds that produce heavy rainfall potentially
leading to flash floods. In this poster, we show results from high-resolution WRF model runs
performed for 3 August, 2013. In particular, studies of the amount of precipitation from two
different cloud situations (isolated and closely packed) are presented to show the importance
of the interaction between the microphysics and dynamics to the development of ice and
precipitation in cumulus clouds.
Comparing impacts of air-sea coupling and mean-state
errors on the MJO across models
Nicholas Klingaman, Senior Research Fellow, NCAS-Climate and
The Madden-Julian oscillation is the dominant mode of tropical sub-seasonal variability. By
influencing regional monsoons, tropical cyclones, the El Niño-Southern Oscillation and extratropical storm tracks, the MJO represents a key source of predictability globally on weekly
and monthly scales. Despite the importance of the MJO, most weather and climate models
fail to simulate its structure, period, amplitude and teleconnections. Many studies have
atmosphere-ocean coupled feedbacks improve the representation of the MJO. However,
there is little consensus on the mechanisms behind this improvement, or on which aspects of
the MJO coupling affects (e.g., period, propagation). Further, large mean-state biases in
coupled models complicate analysis of the role of air-sea interactions and often degrade the
simulation of the MJO. We have developed a modeling framework that comprises an
atmospheric model coupled to many columns of a one-dimensional, thermodynamic ocean.
Within this framework, the ocean mean state is specified through temperature and salinity
corrections. We apply this framework to two models: the Met Office Unified Model (MetUM)
and the Super-Parameterised Community Atmospheric Model (SPCAM). In atmosphere-only
mode, MetUM has a poor simulation of the MJO, while SPCAM produces near-observed
amplitude and propagation. Leveraging our framework, we compare the impacts of air-sea
coupling on the MJO in MetUM and SPCAM, when both models are constrained to the
observed mean ocean state. We also perform simulations in which the models are
constrained to the ocean climatologies from their respective coupled models, to evaluate the
effect of errors in the coupled mean climate on the MJO, and to separate those errors from
the impacts of air-sea coupling. We apply novel process-oriented diagnostics of air-sea
interactions to understand the mechanisms underlying changes in simulated MJO behavior.
The low-resolution version of the UK Earth System Model:
towards an efficient ESM for the UK community
Till Kuhlbrodt, Model Configuration Manager for UKESM-lr, NCAS,
The UK Earth System Model (UKESM) is currently under development. We report on the
progress on the development of the low-resolution version (UKESM-lr) which we plann to
release in Autumn 2016. With a resolution of approx. 150 km in the atmosphere (UM10.3,
N96) and one degree in the ocean (NEMO3.6, eORCA1), this version of UKESM will be
used for the bulk of the CMIP6 simulations. A comprehensive atmospheric chemistry
(UKCA) and a marine biogeochemistry (MEDUSA) are included in UKESM, covering the
global carbon cycle. Here we report on the finalising of the configuration of the model, with a
focus on the long spinup run for the ocean physics and biogeochemistry. Performance of the
current version is compared to a previous version of N96ORCA1 (GC2).
Observed Extreme Rainfall Trend in Hong Kong and
Projection for the 21st Century
Edwin Lai Sau-tak, Assistant Director, Hong Kong Observatory
Other Authors: Sai Ming Lee, Tse Cheung, Hang Wai Tong
The Hong Kong Observatory has been conducting meteorological observations in Hong
Kong for over 130 years. The meteorological data collected over the years serve as an
important basis for monitoring and assessing changes in the climate in Hong Kong. Against
the background of global warming and local urbanization, the long-term meteorological
observations in Hong Kong point to not only a significant warming trend but also increased
occurrences of extreme rainfall events in the past century. The hourly rainfall record at the
Observatory headquarters was broken several times in the last few decades, whereas it
used to take several decades to break the record in the past. Looking into the future, we
summarize here in this poster the latest assessment on projected rainfall trend in Hong Kong
in the 21st century based on results statistically downscaled from daily model data of the
Coupled Model Intercomparison Project Phase 5. Under the high greenhouse gas
concentration scenario (RCP8.5), the annual number of extreme rainfall days (daily rainfall ≥
100 mm) would increase from an observed value of 4.2 during 1986-2005 to 5.1 by the end
of this century (2091-2100). The average rainfall intensity (i.e. annual rainfall divided by the
number of rain days), the annual maximum daily rainfall, the annual maximum 3-day rainfall
and the annual maximum number of consecutive dry days would increase, while the annual
number of rain days would decrease. Projection results for other greenhouse gas
concentration scenarios will also be presented.
The benefit of "convection-permitting" resolution in a
climate model for representation of summer precipitation
variability and extremes.
Petter Lind, Research scientist, PhD student, SMHI
Other Authors: Colin Jones, Erik Kjellstrom, David Lindstedt
Within the climate modelling community, it is still an open research question regarding the
ability of current generation of climate models to provide societies with accurate and reliable
predictions of regional climate change, particularly concerning the statistics of extreme
events and high impact weather including hydrological extremes such as flash floods. This
complicates the efforts to formulate appropriate and necessary strategies for mitigation and
adaptation to climate change on regional and local level. Therefore, there is an urge within
the climate research community, in part driven by expectations from society, to generate
more accurate and reliable predictions of regional weather and climate extreme events than
are possible with the current generation of climate models. In this context, we have run the
HARMONIE regional climate model at "convection-permitting" 2 km horizontal resolution
over a few areas in Europe, including the Alps with its complex terrain where model
resolution is an important factor. The question we seek to answer is how well summer
precipitation characteristics (which is dominated by convective events) on sub-daily time
scales are captured by HARMONIE. Our means to answer this question involves the
evaluation of diurnal timing and the intensities, durations and frequencies of precipitation
spells, with focus on high-intensity events. The model results are evaluated against a
number of different observations, including high-resolution gridded observations based partly
on radar measurements, reanalysis data and point measurements (rain gauges).
Comparison is also performed against two other HARMONIE runs at the coarser 6.25 and
15 km resolutions to investigate the sensitivity to horizontal resolution. In contrast to the 2
km run these model simulations are run with an active convection parametrisation adapted
for high resolution. Our results show a considerably improved realism of the sub-daily
characteristics of precipitation at "convection-permitting" resolution, especially concerning
duration and frequency as well as the atmospheric conditions leading to the events. These
findings indicate a clear benefit of using "convection-permitting" scales, handling convection
explicitly in the model, and a means to increase our confidence in possible changes in
precipitation and its extremes induced by a perturbed climate system.
A new regional climate model operating at the mesogamma scale; performance over Europe
David Lindstedt, Research Scientist, PhD student, SMHI, Swedish
Meteorological and Hydrological Institute
Other Authors: Colin Jones, Erik Kjellstrom, Peter Lind
Present-day state-of-the-art RCM’s operate on horizontal resolutions of ∼10-40 km. Further
increasing resolution without reaching cloud-resolving scales, one reaches the scale
traditionally referred to as the ”grey-zone” (∼3-8 km). At the Rossby Centre, we are working
towards the development of a new regional climate model, based on the non-hydrostatic
NWP model HARMONIE. Accurately representing large scale regional climate variability is
vital when the primary interest is whether HARMONIE at this high resolution improves
representation of higher order regional climate statistics such as intensive precipitation
events. In this study, we present results from a number of initial simulations made with this
new model system, run in climate mode for a ten-year period. We have shown that not only
the large scale climate is very well represented but also on the regional scale and for
higher order climate statistics the model is in overall good agreement with observations.
Decreasing the grid box size from 15 km to 6 km results in a more realistic representation of
extreme precipitation occurrences.
Connections between forecast errors over North America
and the North Atlantic and forecast errors over Europe
Oscar Martinez-Alvarado, Research Scientist, NCAS-Atmospheric
Physics and Department of Meteorology, University of Reading
Recent research suggests that the representation of diabatic processes in numerical
weather prediction models can be a major factor in the development of forecast errors over
the North Atlantic-Europe sector. However, it is not yet clear what type of diabatic processes
can have the most important influence. On the one hand, European forecast busts in six-day
forecasts have been associated with errors in forecasts of Rossby waves propagating from
North America to Europe. It has been hypothesized that at least part of the connection
between these two forecast errors is given by diabatic processes associated with convective
activity over the USA Great Plains. On the other hand, case studies show that errors in fiveday forecasts of Rossby waves over the North Atlantic can be preceded by errors in
forecasts of cyclogenesis over the west Atlantic around two days before. In this case, the
connection between these forecast errors would be provided by the strong diabatic
processes associated with warm conveyor belts. In this contribution, the relationship
between these two pieces of research is explored. Are they describing two aspects of the
same causal process? The investigation is performed via lagged analysis of forecast errors
in relevant variables, such as mean sea level pressure and geopotential height, in
operational forecasts archived by The Interactive Grand Global Ensemble (TIGGE). The
relationships between lagged forecast errors in those variables as well as the physical
processes that could be responsible for those relationships are discussed. The analysis is
performed separately for winter and summer to highlight differences in the physical
processes at play in these two seasons.
How well do medium-range ensemble forecasts simulate
atmospheric blocking events?
Mio Matsueda, Assistant Professor/Academic visitor, University of
Tsukuba/University of Oxford
This study assesses forecast performances of medium-range ensemble forecasts, regarding
atmospheric blocking events in winter (2006/07-2014/15) and summer (2007-2015) over the
Norther and Southern Hemispheres (NH and SH).The medium-range ensemble forecasts
available at the TIGGE data portal, have been provided by CMA (China), CMC (Canada),
CPTEC (Brazil), ECMWF (Europe), JMA (Japan), KMA (South Korea), NCEP (US), and
UKMO (UK).
Generally, models simulate the frequency of blocking in both NH and SH well, even at a lead
time of 15 days, except some extreme blocking events. Verifications based on Brier Skill
Scores (BSS) for probabilistic blocking forecasts show that the probabilistic blocking
forecasts over NH are better than those over SH, although there are some year-to-year
variabilities of the forecast skills. In both hemispheres, probabilistic skills in winter tend to be
higher than those in summer. ECMWF shows much higher skill compared to the other
models for both seasons in both hemispheres. There are larger skill differences among the
models over SH than NH. In both seasons over NH, probabilistic forecasts over the EuroAtlantic region have comparable skills with those over the Pacific region. The probabilistic
forecasts (except CPTEC) become comparable to the climatological forecast after lead times
of 15 days in winter and 10 days in summer. In SH where Australia-New Zealand and Andes
blockings occur, probabilistic forecasts of Andes blocking in winter show highest skills and
are comparable with the climatological forecast after a lead time of 14 days, whereas the
other probabilistic forecasts are comparable to the climatological forecast at lead times of 612 days.
Investigating tropical drivers of North Atlantic/European
Sector summertime variability
Cheikh Mbengue
Other Authors: Helen Dacre, Kevin Hodges, Tim Woollings
Accurate weather predictions help societies plan for and mitigate against adverse effects of
the weather. Today, forecast skill of European wintertime circulation remains significantly
higher than that of the summertime circulation. This gap in forecast skill may reflect possible
gaps in understanding, which likely resulted from a skewed research focus towards
wintertime circulation. Here, theories of the drivers North Atlantic/European Sector
summertime variability are developed and tested using ERA-Interim reanalysis data in
concert with a hierarchy of numerical models. Statistics conditioned on cyclone tracks are
also used to promote insight. Comparing patterns of variability of potential tropical drivers to
patterns of summertime circulation variability helps to enhance understanding of tropical
control of North Atlantic/European summertime circulation variability. For example, it is
shown that variability in the extent of the Northern Hemisphere’s tropical mean meridional
overturning circulation projects onto the dominant modes of Atlantic sector jet variability.
Findings such as this one provide observational evidence supporting tropical control of
midlatitude climate variability and have significant implications for summertime predictability.
A New Radiation Sscheme to explain Rapid Climate
Change
Alastair B. McDonald, Independent Researcher,
The greatest danger facing the world from the increase in anthropogenic greenhouse gases
is that an abrupt climate change occurs, but the climate models are unable to replicate those
events. A simple explanation for both the abrupt warmings and abrupt coolings in the
northern hemisphere is a change in the size of the North Atlantic/Arctic sea-ice pack, since
that would be driven by the positive ice-albedo feedback and by the runaway greenhouse
effect of water vapour. Here is proposed that the climate models fail to simulate abrupt
climate change, because they are based on an incorrect paradigm. A new radiation scheme
is presented where changes to the surface temperature maintain the radiation balance at the
top of the atmosphere by adjusting planetary albedo rather than outgoing longwave
radiation. Since the terrestrial radiation, which is absorbed at the bottom of the atmosphere,
is effectively saturated, an increase in the concentration of greenhouse gases does not
result in more radiation being absorbed. However, the radiation is absorbed closer to the
base of the atmosphere and so warms the Earth's surface. This causes the snow line to rise
in altitude and latitude, and the subsequent decrease in planetary albedo increases the
global temperature. A loss of the Arctic sea ice is already being observed, and when a
tipping point is passed the sea ice sheet will suddenly disappear and an abrupt warming will
result.
A numerical sensitivity study of heavy precipitation event
for domain area in regional numerical weather prediction
model
Jae-Sik Min, Researcher, Weather Information Service Engine
(WISE) Institute
Other Authors: Sangil Kim, Young-Jun Kim
In this study, the synoptic-scale condition and variability of 850 hPa wind speed over the
East Asia region are investigated using the National Centers for Environmental Prediction
(NCEP) Final analysis (FNL) data set from 1 December 2001 to 30 November 2011. A
distribution of strong wind and large variance of wind speed are located in northern and
eastern China during winter season. At summer season, the East China Sea and south sea
of Japan appear large variance of wind speed which is caused by an extended North Pacific
high and typhoon. Based on the results of investigation of synoptic-scale winds, a sensitivity
experiment on precipitation response to domain size has been performed using Weather
Research and Forecasting (WRF) model version 3.6 for heavy precipitation event over the
Korean peninsula on 26-27 July 2011. Numerical experiment of three different domain sizes
are designed with model setup of 5 km (CTL, EXP1) and 9 km (EXP2) grid spacing and 50
levels vertical resolution. We found that major rainfall is led by location of short-wave trough
with baroclinic structure over Northeast China and extended North Pacific High. The
correlations of observation and numerical experiments of 1-h precipitation represent that
EXP2 show the best performance (correlation coefficient: 0.79). We concluded that the
synoptic-scale systems such as short-wave trough and North Pacific High contribute to
performance in experiment of the largest domain.
Exploring the atmospheric impacts of changes in North
Atlantic ocean circulation
Pablo Ortega, Postdoctoral Researcher, NCAS Climate - UREAD
Due to its long memory and its direct effect on the northward heat transport, the ocean
circulation is a key element to understand climate variability in the North Atlantic. Its study is
however hampered by the lack of long-record in-situ observations. Most climate models
support a driving role of deep water formation in the Labrador Sea on the ocean circulation,
and many validate the use of deepwater densities over this region as a relevant proxy for its
variability (Robson et al 2014). Observations show that this index has been decreasing
steadily since the mid 90s, and has been followed over the last decade by a significant
cooling in the eastern subpolar gyre, consistent with the expected reduction in northward
heat transport (Robson et al; Submitted). This study focuses on the atmospheric impacts
following similar decadal trends in Labrador Sea deepwater densities. We first analyse a
300-year long simulation with the HadGEM3-GC2 model (Williams et al 2015), whose ocean
component has a horizontal resolution of 0.25°x0.25°. A composite analysis of the 9 largest
equivalent trends in the simulation reveals significant atmospheric changes following by 5
years the deep density declines. The associated patterns of response show marked
seasonal differences, especially over land. Particularly interesting is the appearance of a
strong positive winter North Atlantic Oscillation, a well-known driver of Labrador deep water
formation, that could thus act as a negative feedback on the ocean circulation. To further
investigate how this atmospheric response is established we are using a new configuration
of the Met Office Unified Model, coupled to a high resolution ocean mixed layer model
(Hirons et al 2015). This recently developed configuration is particularly powerful as it allows
constraining the ocean to any particular state, and examination of the impact of the
associated coupled air–sea interactions on the climate system. Several experiments are
being performed to isolate the particular regions and processes responsible for changes in
the atmospheric circulation
Ocean-atmosphere state dependence of the response to
sea ice loss
Joe Osborne, Associate Research Fellow, University of Exeter
Other Authors: Matthew Collins, James Screen
A large number of recent studies have explored the local and remote effects of Arctic sea ice
loss. But can natural ocean-atmosphere variability modulate the response to diminished sea
ice cover? Here, we use an atmospheric general circulation model (AGCM) to test the
sensitivity of the response to sea ice loss to the phase of the Atlantic Multidecadal Oscillation
(AMO), which varies on multi-decadal timescales. In these experiments, a wave-train
response to wintertime sea ice loss is seen in the Pacific-North America sector in the
negative phase, which is missing in the positive phase. This anomalous wave-train may be
triggered by sea ice loss in the Sea of Okhotsk and the resulting enhanced meridional SST
gradient in the western North Pacific in the negative AMO phase. Other possible physical
mechanisms behind these state dependencies are discussed, as well as evidence for similar
responses in observations.
A Complex Networks Analysis of StratosphereTroposphere Teleconnections
Scott Osprey, NCAS Scientist, NCAS-Climate and Department of
Physics, University of Oxford
As focus for the impacts of anthropogenic global warming (AGW) increasingly turn to
regional scales, it is widely appreciated that dynamical rather than thermodynamic drivers of
regional circulation responses and their associated extremes become more important.
Regional circulation and its response to AGW not only involves localised processes, but also
those nonlocal integrators of regional circulation - global teleconnection patterns - including
phenomena such as the North Atlantic Oscillation, Atlantic Multi-decadal Oscillation, the
Pacific Decadal Oscillation and the El Nino Southern Oscillation. The role these large-scale
modes of variability play in the expression of regional circulation change and extremes is not
only of pressing concern for government agencies in planning adaptation strategies, but is in
itself an open and active area of scientific research. There is Increasing evidence that upper
atmosphere variability can covary with (or impact) tropospheric weather, especially at high
latitudes during boreal winter. The ability of global climate models to capture the relevant
processes and feedbacks involved in these ‘stratosphere-troposphere teleconnections’ is
crucial if tropospheric forecasts are to benefit from reproducing stratospheric phenomena
that are potentially predictable from weekly through to interannual timescales. We will
describe recent advances in Complex Network Theory which can identify non-local and
potentially nonlinear links between different parts of the climate system. Our focus here we
will be on stratosphere and troposphere covariability. We will show that these techniques not
only identify events historically implicated in stratosphere-troposphere coupling, but also
highlight a wider spectrum of covariability which has been largely under-reported by the
research community.
Impact of sea-air interactions on the summer tropicalextratropical teleconnections over North Atlantic and
Europe
Albert Ossό, Research Scientist, NCAS
Other Authors: Len Shaffrey, Buwen Dong, Rowan Sutton
The influence of air-sea interactions on the North Hemisphere summertime atmosphere
mean state and interannual variability is analyzed in two 45-yr long experiments with the
MetOffice Unified Model. In the first experiment, the atmosphere is allowed to freely interact
with a high resolution mixed-layer model, and then the diagnosed daily SSTs from this
experiment are used to force a second simulation where atmosphere-ocean interaction is
suppressed. In the coupled experiment, the summer-mean North Atlantic eddy-driven jet is
shifted poleward and the subtropical jet is shifted equatorward compared with the uncoupled
experiment. The coupled experiment exhibits about two times less precipitation variability
over the tropics compared with the atmosphere-only experiment and it is much less biased
against observations. A better representation of tropical precipitation variability in the
coupled experiment is especially apparent over the Indian-monsoon area, where the
precipitation response to SSTs when suppressing air-sea interactions is too vigorous. It is
found that the coupled experiment is able to capture the westward propagating Rossbywave
trains exited by the Indian monsoon, while the uncoupled experiment is not. The
analysis suggests that the equatorward shift of the subtropical jet stream when including
airsea interactions is critical to permit the interaction between the Indian monsoon and the
westerly jet that generate the westward propagating Rossby wave trains.
Sources of forecast error in the short term prediction of
drought in the UK
Tess Parker, Postdoctoral Research Assistant, AOPP, Department
of Physics, University of Oxford
Other Authors: Antje Weisheimer, Tim Woollings
The current capability to produce skilful, reliable and useful meteorological forecasts of
European climate on monthly to seasonal time scales is limited, in particular for precipitation.
Increased model resolution and the development of new parameterisations have led to an
improvement in the representation of some meteorological drivers of drought in climate
models, such as ENSO teleconnections over Europe, anticyclonic blocking, North Atlantic
weather regimes, and Northern Hemisphere stationary wave patterns. Key to the
development of skilful monthly to seasonal or longer forecasts is a deeper understanding of
the meteorological drivers which may lead to enhanced predictability of drought events in the
UK. Recently identified key drivers include North Atlantic sea surface temperatures,
stratospheric-tropospheric interactions, and tropical-extratropical interactions such as the
impact of the Madden-Julian Oscillation on the North Atlantic Oscillation. The contribution of
these drivers to the evolution of individual drought events in the UK is not yet known. Our
research investigates one of the most severe multi-annual drought events in the UK from
winter 2009/10 to winter 2011/12. An ensemble of models is used to investigate the sources
of forecast error in the short-term prediction of drought. An analysis of blocking events as
well as the sensitivity of blocking to atmospheric variables such as mid-tropospheric and
stratospheric geopotential height is presented. The role of ENSO, the NAO, Rossby wave
breaking, and tropical-extratropical interactions including the MJO and tropical storms will
also be discussed.
Future Challenges for Operational Surface Water Flood
Forecasting in Scotland
Louise Parry, Senior Hydrometeorologist, SEPA
Other Authors: Michael Cranston, Richard Maxey
In July, 2002, the east end of Glasgow was inundated during a severe flood event, which
affected nearly 500 homes, the railway network, and caused millions of pounds worth of
damage. In the 14 years since there has been an increase in occurrence of high profile
summer surface water flood events across Scotland, as well as the UK in general.
Forecasting these events poses a significant challenge to the operational and research
communities as pluvial flooding is strongly linked to the occurrence of convective rainfall
events which can be highly localised and are notoriously difficult to forecast. In addition, the
resultant impacts and hazards of an event are extremely location specific.In July, 2014,the
Scottish Flood Forecasting Service (SFFS) successfully piloted the UK's first operational
surface water flood risk forecasting model with a 24-hour lead time over the east end of
Glasgow during the Commonwealth Games. The forecasting system used detailed off-line
surface water flood maps to identify hazards in areas forecast to be at risk in a 100km 2 Gridto-Grid (G2G) hydrological model (1km resolution) adapted for surface water flow and
inundation, and driven with the Met Office short range (36 hour) 24-member ensemble
forecasts and the STEPS nowcast ensemble. The question now is how best to modify or
develop further the SFFS surface water flood forecasting capability based on lessons learnt
from the pilot, and developments in the observation network and the NWP and hydrological
models, since the pilot study.Options for extension of the surface water flood forecasting
capability include rolling out a national scale model or development of regionalised models
or tools for other urbanised areas across Scotland. In addition, we are researching options
for case (client) specific forecasts such as for transport infrastructure, and as such are keen
to engage with the wider research community and encourage case studies and research in
Scotland.
A Global Flash Flood Prediction System
Fatima Pillosu, Graduate Trainee, ECMWF, Reading
ECMWF (the European Centre for Medium range Weather Forecasts) is developing a global
system for predicting flash floods. A general overview of this project will be provided. As its
input the system will use forecast fields from the ECMWF global ensemble prediction
system. Post-processing techniques convert the global model forecasts for gridboxes into
probabilistic forecasts for rainfall at any point within those gridboxes, and flash flood alerts
will then be based on those point forecasts. The post-processing techniques are key to the
success of this system; they aim to incorporate the degree of sub-grid variability expected
within each grid box. These techniques have been “meteorologically informed”. This means
that they rely on (a) a detailed physical understanding of rainfall generation mechanisms,
and (b) study of individual cases of flash flooding. In (b) we want to ensure that the
atmospheric structures that are believed to allow very large totals to accrue over small areas
in a short time are present in real cases, and that such structures can be foreseen using
output from the global model itself. This poster will highlight what we understand the key
factors to be, using case studies such as the devastating Tbilisi floods of June 2015, and
physical reasoning, to illustrate. Furthermore, it will be shown that standard global model
output does contain information that is pivotal in identifying when the atmospheric
configuration has the potential to deliver flash floods, even though the pure rainfall forecast
from the model is often not, itself, extreme, and so would not, if taken literally, provide any
warning.
Assessing spatial precipitation uncertainties in a
convective-scale ensemble
Robert Plant, Associate Professor, University of Reading
Other Authors: Seonaid Dey, Stefano Migliorini, Nigel Robers
New techniques have recently been developed to quantify the location-dependent spatial
agreement between ensemble members, and between the ensemble members and radar
data. This can be used to obtain a spatial spread-skill relationship for precipitation. A
summer of convection-permitting ensemble forecasts are analysed using this approach,
taken from the summer 2013 of the MOGREPS 2.2km ensemble system, and factors
influencing the spatial agreement of precipitation fields are identified. Overall, the system
was found to be well spread for this summer, albeit with some indications for the ensemble
to be over confident in the location of precipitation. For the forecast lead times considered
(up to 36 hrs) a diurnal cycle was seen in the levels of spatial agreement and in the spatial
spread-skill relationship. Both the spatial agreement, and the spatial spread-skill, were also
dependent on the fractional coverage and (to a lesser extent) on the average intensity of
precipitation. A poor spread-skill relationship was associated with a low fractional coverage
of rain, and extreme (either high or low) average rain rates. The spatial agreements obtained
were also found to be location dependent, with higher confidence in the location of
precipitation in the northwest of the UK.
A national-scale hydrological simulation of low flows and
drought across Britain
Alison Rudd, Hydrological Modeller, Centre for Ecology &
Hydrology, Wallingford
Other Authors: Victoria Bell, Helen Davies, Alison Kay
There have been numerous studies on floods in the United Kingdom, but until recently
drought research has been comparatively neglected. The launch of a five-year NERCfunded interdisciplinary research programme “UK Droughts and Water Scarcity” is allowing
researchers to address this. Our work on one of these projects, MaRIUS (Managing the
Risks, Impacts and Uncertainties of droughts and water Scarcity), uses a national-scale
hydrological model, previously used extensively for flood studies, to identify drought periods.
The model is driven by a new long-term (1890 - 2012) precipitation dataset (CEH-GEAR)
and estimates of potential evaporation. Model performance is assessed against observed
river flows for low flow and drought periods. Concepts such as severity and duration have
been used to identify historic hydrological droughts across Britain from model output, by
examining gridded time series of monthly mean river flow and soil moisture. We also
investigate how drought occurrence and severity have changed over the last 100 years and
identify regions that have been particularly susceptible to drought.
The Systematic Effects of Parametrized Physical
Processes in a Numerical Weather Prediction Model
Leo Saffin, PhD Student, University of Reading
Numerical models of the atmosphere combine a dynamical core, which approximates
solutions to the adiabatic and frictionless governing equations, with the tendencies arising
from the parametrization of physical processes. Tracers of potential vorticity (PV) can be
used to accumulate the tendencies of parametrized physical processes and diagnose their
impacts on the large-scale dynamics. This is due to two key properties of PV, conservation
following an air mass and invertibility which relates the PV distribution to the balanced
dynamics of the atmosphere. Applying the PV tracers to many short forecasts allows for a
systematic investigation of the behaviour of parametrized physical processes. The forecasts
are 2.5 day lead time forecasts run using the Met Office Unified Model (MetUM) initialised at
0Z for each day in November/December/January 2013/14. The analysis of the PV tracers
has been focussed on regions where diabatic processes can be important (tropopause
ridges and troughs, frontal regions and the boundary layer top). The tropopause can be
described as a surface of constant PV with a sharp PV gradient. Previous work using the PV
tracers in individual case studies has shown that parametrized physical processes act to
enhance the tropopause PV contrast which can affect the Rossby wave phase speed. The
short forecasts show results consistent with a systematic enhancement of tropopause PV
contrast by diabatic processes and show systematically different behaviour between ridges
and troughs. The implication of this work is that a failure to correctly represent the effects of
diabatic processes on the tropopause in models can lead to poor Rossby wave evolution
and potentially downstream forecast busts.
Impacts of climate change on hot days and heat waves in
the UK
Michael G. Sanderson, Senior Applied Scientist, Met Office
Other Authors: George Ford
Hot days and heat waves are known to cause mortality in the very old and very young, and
those with existing conditions such as heart disease. This study examines projected
changes in hot days and heat waves in the United Kingdom. Methods: Hot days and heat
waves are defined using temperature thresholds from a heat wave plan operated by Public
Health England; heat alerts are issued to the public by the Met Office. These thresholds are
linked to available epidemiology and have been shown to be consistent with a 15-20%
increased risk of mortality. The UK is divided into 16 administrative regions, and thresholds
are defined for each region. The highest threshold temperatures are used for London and
south east England, and the lowest for north east England. Daily maximum and minimum
temperatures from an ensemble of eleven regional climate model projections for the period
1970-2089 were analysed. These projections were created using a medium emissions
scenario. The modelled temperatures were bias-corrected before use. Results: Hot days and
heat waves were projected to increase in number across the UK as the climate warms. The
“hot season”, the number of days between the first and last hot day of the year was
projected to increase by up to 40-50 days by the 2080s. In western areas of the UK,
changes in the distributions of heat wave lengths were small throughout the 21st century. In
contrast, a small number of extremely long heat waves (15-28 days) were simulated in
eastern areas of England during the second half of the 21st century. The number of regions
affected by heat waves on any given day also increased as the climate warmed. In the
present day climate, almost all heat waves have occurred during July and August. During the
second half of the 21st century, heat waves were projected to occur between June and
September, and occasionally May in some regions. Conclusion: Hot days and heat waves
are projected to increase in number, and appear both earlier and later in the year as the
climate of the UK warms. In eastern areas of England, extreme heat waves lasting 15-28
days were projected to occur about once every decade. Combined with the aging population,
excess mortality from hot days and heat waves is likely to increase in the future unless
suitable adaption measures are implemented. Impact-based forecasts, an existing Met
Office capability, could support appropriate mitigation strategies and policy changes.
Evaluation of extreme precipitation over European river
basins in global Met Office Unified Model high-resolution
climate simulations
Reinhard Schiemann, Senior Scientist, High Resolution Climate
Modelling, NCAS Climate, University of Reading
Other Authors: Marie-Estelle Demory, Matthew Mizielinski, Malcolm Roberts. Jane
Strachan, Pier Luigi Vidale
Flood events affecting large European river basins of a drainage area of < (100 000 km2 )
are largely caused by extreme precipitation over these river basins immediately preceding
the river floods and lasting for one or several days. In this study, we evaluate the
representation of such extreme precipitation events in the Met Office Unified Model
(MetUM). Extreme-value distributions of basin-scale precipitation are estimated for highresolution (down to about 25 km grid spacing) global MetUM simulations conducted in the
project UPSCALE (UK on PRACE: weather- resolving Simulations of Climate for globAL
Environmental risk), and for gridded gauge-based reference precipitation from the European
Climate Assessment & Dataset (ECA&D) E-OBS product.
Why is the tropical cyclone boundary layer not well-mixed?
Juliane Schwendike, Lecturer in Meteorology, University of Leeds
Other Authors: Jeffrey Kepert, Hamish Ramsay
Plausible definitions for the tropical cyclone boundary layer include (i) the depth of the inflow
layer and (ii) the depth over which potential temperature is approximately constant.
Observations show that these two candidate definitions are markedly different in practice,
with the inflow layer being roughly twice the depth of the well-mixed layer. This discrepancy
is a hindrance to our understanding, and has a potentially large impact on those boundary
layer parameterisations that rely on the diagnosis of the boundary layer depth. Here, we will
present an analysis of the thermodynamics of the tropical cyclone boundary layer derived
from an idealized axisymmetric model, and demonstrate why the two depths are different.
We show that the marked dry static stability in the upper part of the inflow layer is largely due
to diabatic effects. As the radial wind varies strongly with height, so does the radial advection
of the potential temperature, which also contributed to the stabilization of the boundary layer.
Additionally, this differential vertical advection of stability contributes to the observed
superadiabatic layer adjacent to the ocean surface, where the vertical gradient of the radial
wind is reversed. However, this unstable layer is mainly due to heating from turbulent
dissipation. The results will be compared with dropsonde observations, and implications for
boundary layer parameterisation will be discussed.
Decadal Predictions using the high-resolution HiGEM
climate model
Len Shaffrey, Principal Scientist, NCAS, University of Reading
Developing skillful and statistically reliable climate predictions on seasonal to decadal
timescales is one of the grand challenges of climate science. Skillful seasonal to decadal
predictions would have substantial socioeconomic benefits, informing investment across a
wide range of economic sectors. To explore the question of how increased resolution might
improve predictions at regional scales, a high resolution global coupled climate model,
HiGEM, has been developed. This model is based on the Met Office Hadley Centre global
coupled climate model, HadGEM1. In HiGEM the horizontal resolution in the atmosphere is
increased to 1.25x0.83 degrees longitude by latitude, while the resolution in the ocean is
increased to an eddy-permitting resolution of 1/3x1/3 degrees. Increasing the horizontal
resolution results in an improved representation of a number of climate phenomena in
HiGEM, including ENSO, Northern Hemisphere planetary waves and subtropical
stratocumulus. We have completed a set of decadal predictions using HiGEM following the
CMIP5 protocol, producing an ensemble of 10 year predictions starting every five years from
1960 to 2005. The methodology for the HiGEM decadal predictions is based on that used in
Met Office DePreSys system, where the ocean model is initialised using anomaly
assimilation. The skill of the HiGEM decadal predictions will be presented. In particular,
HiGEM is capable of skillfully predicting the evolution of ocean temperatures in the North
Atlantic subpolar gyre on lead times of up to four years.
Projecting the sea level rise contribution from the
Greenland and Antarctic ice sheets: the UK contribution to
ISMIP6
Robin Smith, Research Scientist, NCAS-Climate / Dept. of
Meteorology, University of Reading
The sea level projections made by the glaciological community as part of the
Intergovernmental Panel on Climate Change (IPCC) process have often been out of phase
with the projections considered by the wider climate modelling community. A new
international project, ISMIP6, aims to allow ice sheet models to be better integrated into the
major climate modelling intercomparison exercises, in order to improve both sea level
projections due to changes in the cryosphere and our understanding of the cryosphere in a
changing climate. The UK will be participating in ISMIP6 using the new Earth System model
UKESM1, jointly developed by a team from NERC and the MetOffice. In this poster we
discuss the newly-developed aspects of UKESM1 that will be used for ISMIP6 and show
some early results.
Correlating high impact weather hazards for global
reinsurance risk assessment
Hamish Steptoe, Applied Climate Scientist, Met Office
Other Authors: Theo Economou, Helen Fox, Paul Maisey, Trevor Maynard, Emily
Wallace
Concurrent high impact weather hazards represent an uncertainty in assessing exposure for
the insurance industry. The recently implemented Solvency II Directive requires EU
insurance companies to fully understand and justify their capital reserving and portfolio
decisions. Lloyd's, the London insurance and reinsurance market, commissioned the Met
Office to investigate the dependencies between different global extreme weather events
(known to the industry as perils), and the mechanisms for these dependencies, with the aim
of helping them assess their compound risk to the exposure of multiple simultaneous
hazards.In this work, we base the analysis of hazard-to-hazard dependency on the
interaction of different modes of global and regional climate variability. Lloyd's defined 16
key hazard regions, including Australian wildfires, flooding in China and EU windstorms, and
we investigate the impact of 10 key climate modes on these areas. We develop a statistical
model that facilitates rapid risk assessment whilst allowing for both temporal auto-correlation
and, crucially, interdependencies between drivers. The simulator itself is built conditionally
using autoregressive regression models for each driver conditional on the others. Whilst the
baseline assumption within the (re)insurance industry is that different natural hazards are
independent of each other, the assumption of independence of meteorological risks requires
greater justification. Although results suggest that most of the 120 hazard-hazard
connections considered are likely to be independent of each other, 13 have significant
dependence arising from one or more global modes of climate variability. This allows us to
create a matrix of linkages describing the hazard dependency structure that Lloyd's can use
to inform their understanding of risk.
An empirical model for annual-to-decadal probabilistic
prediction of changes in regional extremes
Emma Suckling, Research Scientist, University of Reading
Empirical models, designed to predict land-based surface variables over seasons to
decades ahead, not only provide useful benchmarks for comparison against the
performance of dynamical forecast systems, but could potentially be employable as
predictive tools in their own right, or in combination with dynamical models.
A new empirical seasonal-to-decadal prediction system, based on a multiple linear
regression approach and designed to produce ensemble output for a number of surface
climate variables, has been developed and evaluated in terms of its hindcast skill. The model
has previously demonstrated skill in terms of predicting seasonal and annual mean
temperature and precipitation across the globe [1,2], but how well can such empirical models
capture the probabilities of extremes at regional scales? This question will be examined in
the context of temperature and wind extremes across the Europe and Asia regions.
[1] J. Eden, G. J. van Oldenborgh, E. Hawkins and E. Suckling, A global empirical system for
probabilistic seasonal climate prediction, Geosci. Model Dev. Discuss., 8, 3941-3970 (2015),
doi:10.5194/gmdd8-3941-2015
[2] E. Suckling, E. Hawkins, G. J. van Oldenborgh and J. Eden, An empirical model for
probabilistic decadal prediction: A global analysis, Clim. Dyn. (2015)
Maritime Continent Precipitation in CMIP5 Model AMIP
Simulations
Ying Ying Toh, PhD Student, Department of Meteorology, University
of Reading
The fidelity of Coupled Model Intercomparison Project Phase 5 (CMIP5) models in
simulating mean climate over the Maritime Continent in uncoupled mode is evaluated in this
study. The 28 CMIP5 model simulations for the 30-year period (1979-2008) in Atmospheric
Model Intercomparison Project (AMIP) configuration with prescribed SSTs and sea ice are
compared with observational datasets. The performance of CMIP5 model in the AMIP
experiment varies greatly in reproducing seasonal mean climate and its annual variations.
The multi-model mean has better skill in reproducing the observed mean climate than the
individual models. The 850hPa wind is better simulated than the precipitation in all four
seasons. An assessment of the sensitivity of Maritime Continent precipitation to climate
model resolution shows that the model horizontal resolution is not a good indicator of model
performance. Instead, we show that the local Maritime Continent biases are somewhat
related to global circulation and global monsoon biases. The models that have a better
representation of the Hadley Circulation and global monsoons have a better representation
of the seasonal mean of precipitation and winds over the Maritime Continent.
The impact of stochastic physics on tropical rainfall
variability
Peter Watson, Postdoctoral Researcher, Oxford University
Stochastic physics may be expected to enhance tropical variability by improving the
representation of unresolved convective systems, and has been shown to substantially
improve tropical weather forecasting skill. In modern climate models, the simulated variability
of tropical rainfall with periods of several days or less is generally too small. Including
multiplicative-noise stochastic physics increases the variability at short periods, with smaller
impacts on longer period events, and improves the simulated variability at most periods and
length scales. Stochastic physics may therefore be important for simulating the variability of
tropical rainfall well. The impact of stochastic physics on the simulation of intense rainfall will
also be examined, and implications for attributing events to anthropogenic climate change
will be discussed.
Understanding the large-scale dynamics of the 2013/14
winter extremes
Peter Watson, Postdoctoral Researcher, Oxford University
The 2013/14 winter brought heavy rainfall and severe flooding to the UK and very cold
temperatures to the eastern USA. Seasonal forecast systems did not give clear warning of
the events, raising the issue of whether models are able to simulate the relevant processes,
and it has also been suggested that anthropogenic climate change had a role understanding such issues requires understanding the drivers of the extremes. One
suggested driver was large positive precipitation anomalies in the tropical West Pacific
(TWPAC), possibly caused by raised sea surface temperatures. We show that relaxing the
TWPAC atmosphere towards reanalysis produces a strong Rossby wavetrain over the North
Pacific and North America in January, but not in the winter-mean. This suggests that
anomalies in this region alone had a large influence, but cannot explain the extremes
through the whole winter. We also examine the response to applying the observed TWPAC
SST anomalies in two atmospheric general circulation models. We find that this does
produce winter-mean anomalies in the North Pacific and North America resembling those
observed, but that the tropical forcing of Rossby waves due to the applied SST anomalies
appears stronger than that in reanalysis, except in January. Therefore both experiments
indicate that the TWPAC influence was important, but the true strength of the TWPAC
influence is uncertain. None of the experiments indicate a strong systematic impact of the
TWPAC anomalies on Europe. We will also discuss the connection between the extremes in
North America and Europe and their link to the stratosphere.
Distributions of rainfall in simulated present and future
climates, globally and in South East Asia
Ian Watterson, Senior Principal Research Scientist, CSIRO
Atmosphere and Oceans
Other Authors: Helen Geng, Jack Katzfey, Marcus Thatcher
The impacts of changes in precipitation in a warmer future climate depend on the distribution
and time scales of rain events, as much as the overall seasonal means. But even projected
changes in means are uncertain, given the wide range of results for the end of the century
from the CMIP5 ensemble of climate models. The intensity of daily rainfall tends to increase
in simulations of a warmer climate, but models with higher resolution are needed for realistic
simulations of extremes. Southeast Asia is a particularly challenging region, as seasonal
monsoons and tropical cyclones interact with complex topography and sea surface
temperature (SST) variations to produce high rainfall variability. With regard to a wide range
of impacts, we assess the full distribution of daily precipitation amounts from both CMIP5
GCMs and CSIRO’s CCAM (Conformal Cubic Atmospheric Model), used for dynamical
downscaling. The CCAM simulations are driven by bias-corrected SSTs from six CMIP5
models, initially at a resolution of around 50 km over the globe, then at 10 km over the
Indochina Peninsula. The distributions for 1986-2005 are compared with observational
products from the Global Precipitation Climatology Centre (Germany) and ECMWF -the
ERA-Interim reanalysis, along with other data sets. Objective skill scores for various
statistics, including the average of the top percentile of amounts in each of the four seasons,
are evaluated. While most of the models produce fairly realistic rainfall on the larger spatial
and longer time scales, there is a wide range of outcomes for both low and high extreme
amounts. CCAM can simulate higher extremes with more detail, for example across
Vietnam, with its complex orography. For much of the globe, the CMIP5 ensemble mean
distribution of precipitation broadens in the climate for 2080-2099 under the RCP8.5
scenario, along with a shift towards higher amounts at higher latitudes, and towards lower
amounts and more dry days in much of the subtropics. The top-percentile rainfall tends to
increase more, as a percentage, than the means. However projections for any region must
represent a range of possible outcomes. CCAM adds spatial variation to the changes, but
there remains a range across the six results at each resolution, linked to the differing SST
changes. Atmospheric circulation anomalies associated with the top-percentile events at a
selection of locations are assessed, along with any implications for the reliability of simulated
changes for the coming century.
The extreme European summer of 2012
Laura Wilcox, Senior Research Fellow, NCAS- Climate,
Other Authors: Buwen Dong, Timothy Sutton
Summer (JJA) 2012 was the wettest in the UK since 1912, with increased precipitation
frequency and amount, while 2012 was the second wettest year overall since 1910. This
summer occurred as part of a pattern of anomalously wet UK and northwest European
summers since the late 1990s. Additionally, summer 2012 was anomalously dry in Southern
Europe, with 50-75% of normal precipitation. Summer 2012 is characterised by a strong
negative NAO pattern in JJA. There was a southward and eastward displacement of the jet
over Europe, with most storms tracking along the northern flank and across the British Isles.
Dong et al. (2013) suggest a key role for global SST and SIE, and North Atlantic SST in
particular, in the European extremes of JJA 2012. We test a new methodology for event
attribution using the coupled mixed layer model capability (HadGEM3-GOML) with 2012 as a
case study. We will compare 2012 simulations with HadGEM3-GOML to existing simulations
with HadGEM3-A (as used in Dong et al., 2013) to determine the influence of coupling to a
mixed layer ocean on the attribution conclusions for the event.
Meteorological Controls on Ozone Production and LongRange Transport
Oliver Wild, Reader in Atmospheric Science, Lancaster University
Meteorological processes play an important role in regulating both the production and longrange transport of oxidants through their influence on chemical processing and their control
of lifting and scavenging processes. This study quantifies the daily variability in ozone
production and transport following the emission of precursors (NOx, CO and VOC) from
North American, European and East Asian source regions in springtime using a global
chemistry-transport model. We show how the timing and location of lifting and removal
processes modulates ozone production and export, and assess the impact of this variability
on regional ozone build-up (compromising air quality) and on global ozone (influencing
climate).
Transatlantic flight times and climate change
Paul Williams, Royal Society University Research Fellow, NCAS
Climate, University of Reading
Aircraft do not fly through a vacuum, but through an atmosphere whose meteorological
characteristics are changing because of global warming. The impacts of aviation on climate
change have long been recognised, but the impacts of climate change on aviation have only
recently begun to emerge. These impacts include intensified turbulence and increased takeoff weight restrictions. Here we investigate the influence of climate change on flight routes
and journey times, by feeding synthetic atmospheric wind fields generated from climate
model simulations into a routing algorithm of the type used operationally by flight planners.
We focus on transatlantic flights between London and New York, and how they change
when the atmospheric concentration of carbon dioxide is doubled. We find that a
strengthening of the prevailing jet-stream winds causes eastbound flights to significantly
shorten and westbound flights to significantly lengthen in all seasons, causing round-trip
journey times to increase. Eastbound and westbound crossings in winter become
approximately twice as likely to take under 5h 20m and over 7h 00m, respectively.
Extrapolation to all transatlantic traffic suggests that aircraft may collectively be airborne for
an extra 2,000 hours each year, burning an extra 7.2 million gallons of jet fuel at a cost of
US$22 million, and emitting an extra 70 million kg of carbon dioxide.
The role of thermodynamic and dynamic forcing from the
Tibetan Plateau region in the Met Office Unified Model
Mike Wong, Post-doctoral research scientist, NCAS-Climate and
Other Authors: Reinhard Schiemann, Andrew Turner
The Tibetan Plateau has long been thought instrumental in the establishment and
maintenance of the Asian summer monsoon, with surface sensible heating during springtime
leading to heating deep into the troposphere. This leads to the reversal of the meridional
tropospheric temperature gradient driving the monsoon circulation. More recently, the
relative role of this thermal forcing from the Tibetan Plateau versus dynamical forcing has
been brought into question. Some research highlights the importance of the Himalayas
acting as a mechanical block to the influx of low entropy air, preventing it reaching the
monsoon domain. The work in this study forms part of the new Climate Science for Services
Partnership (CSSP) China on the Tibetan Plateau. We will assess the relative role of the
Tibetan Plateau region dynamic and thermodynamic forcing on the regional temperature and
moisture distribution and hence on the formation of the South and East Asian monsoons.
The study will use the Met Office Unified Model (MetUM) and will also examine the impact of
forcing from the Tibetan Plateau region on downstream circulation over East Asia and the
Western North Pacific. In addition we will also outline our plans for participation in the
Global Monsoons Model Intercomparison Project (GMMIP), in which the role of the Tibetan
Plateau is a key scientific question.
Severe Weather over East Africa
Beth Woodhams, Postgraduate Researcher, Institute for Climate
and Atmospheric Science, University of Leeds
East Africa experiences a complex pattern of rainfall both spatially and temporally. Although
its two main rainy seasons are governed by the passage of the ITCZ, the amount and timing
of wet spells is highly variable both on interannual and intraseasonal timescales. In addition,
rainfall patterns vary spatially over the region due to the complex topography and existence
of large water bodies, such as Lake Victoria. Correctly predicting the rainfall, especially
intense storms, is vital for agriculture in the region and for assessing flood hazard. The
spatial and temporal characteristics of rainfall over East Africa are presented using satellitederived observations from the Tropical Rainfall Measuring Mission (TRMM). Particular
attention is paid to the most severe events. The length and spatial scale of wet spells and
the associated intensity of rainfall is presented for the different climatic zones within East
Africa. The atmospheric conditions and circulation associated with wet spells of various
severity are also analysed. The Met Office currently runs a state-of-the-art operational model
over East Africa with 4km horizontal grid-spacing. The model output is disseminated to
meteorologists in the region to use in their 1 to 2 day weather forecasts. Its high resolution
allows convection to be represented explicitly. This reduces some of the long-standing
biases associated with parameterised convection, such as the timing of the diurnal cycle of
precipitation. Characteristics of the model rainfall are evaluated against the observations to
give insight into how well the model is able to predict different types of rainfall event and its
performance over the different climatic zones. This information will be used to advise
regional forecasters how best to use information from the model in making their forecasts, as
well as to suggest possible improvements to the model itself.
The climate change response of high-impact blocking
weather systems
Tim Woollings, Associate Professor, University of Oxford
Other Authors: Stuart Anderson, Jonathan Fairman, Sharon Gardner
Mid-latitude weather and climate are dominated by the jet streams and associated eastwardmoving storm systems. Occasionally, however, these are blocked by persistent anticyclonic
regimes known as blocking. Climate models generally predict a small decline in blocking
frequency under anthropogenic climate change. However, confidence in these predictions is
undermined by, among other things, a lack of understanding of the physical mechanisms
underlying the change. Here we analyze blocking (mostly in the Euro-Atlantic sector) in a set
of sensitivity experiments to determine the effect of different parts of the surface global
warming pattern. We also analyze projected changes in the impacts of blocking such as
temperature extremes. The results show that enhanced warming both in the tropics and over
the Arctic act to strengthen the projected decline in blocking. The tropical changes are more
important for the uncertainty in projected blocking changes, though the Arctic also affects the
temperature anomalies during blocking.
Quantifying the effect of radar observational uncertainty
on the verification of kilometer-scale NWP precipitation
forecasts using the Fractions Skill Score
Lesley Allison, Research Scientist, Met Office
Other Authors: Marion Mittermaier, Katie Norman, Robert Scovell, Chris Vernon
Through advances in computational power and improvements in numerical weather
prediction (NWP) models, forecasts at kilometer-scale resolution are now becoming routine.
While providing precipitation forecasts that are deemed more realistic (particularly in the
intensity and spatial characteristics of convective precipitation), these high-resolution models
can be penalised by traditional verification metrics for failing to exactly match the observed
rainfall at the (inherently unpredictable) grid scale. For this reason, a number of new spatial
verification methods have been developed to better assess the true quality of forecasts. The
Fractions Skill Score (FSS) is one such metric, which assesses the fractional coverage of
precipitation at a variety of spatial scales, from the grid scale to the whole domain.
When performing forecast verification, the observed values are commonly treated as “truth”,
and differences between the forecast and observed fields are generally attributed to model
error. However, observational uncertainty can be large, particularly in complexly-derived
fields such as the Quantitative Precipitation Estimates (QPE) from radar. These are typically
used for computing the FSS. In this study, we make use of a new radar ensemble product
that has been developed for the UK radar network, which accounts for the effects of random
errors in the vertical profile of reflectivity (VPR) on the QPE derivation, yielding an ensemble
of estimated rainfall rates. We use this radar ensemble in the precipitation verification of the
operational Met Office UKV model, which provides deterministic forecasts for the UK at 1.5
km resolution. The range in FSS (rFSS) across the ensemble varies with the spatial scale
and accumulation threshold considered, but early estimates indicate that it may be ~10% of
the traditional ‘single radar field’ score, and substantially larger at high accumulation
thresholds. This evidence suggests that the (usually unaccounted for) effect of radar
observational uncertainty on NWP verification metrics can be relatively large, and should be
taken into account when assessing the relative performance of forecasts from different
modelling systems, especially when using absolute accumulation thresholds.
Seasonal prediction of UK regional precipitation using
atmospheric drivers
Laura Baker, PhD Student, University of Reading
Other Authors: Len Shaffrey
Recent advances in seasonal forecasting capability mean that the Met Office’s seasonal
forecast system (GloSea5) can skilfully represent the large-scale atmospheric circulation,
such as the NAO (Scaife et al., 2014). We show that the large-scale circulation forecasts can
be used to provide skilful forecasts of UK regional precipitation.
A simple multiple linear regression model is developed to describe the observed
(HadUKP) winter precipitation variability in nine UK regions, using two <span>pressurebased indices. Precipitation in the north-west of the UK is driven mainly by a pressure dipole,
similar to the NAO but shifted to the east; precipitation in the south-east of the UK is driven
by low pressure centred over the UK; other areas are driven by a combination of these two
modes of pressure variability. The multiple linear regression model describes up to 76% of
the observed precipitation variability in each region.
GloSea5 hindcasts are shown to skilfully represent these two pressure indices.
Applying the multiple linear regression model to GloSea5 hindcasts is shown to give
improved skill over the precipitation forecast by the model, with particularly large
improvement in Scotland.
A Vehicle OverTurning Model: Forecasting risk of
disruption on the UK road network during winter storms
Rebecca Hemingway, Weather Impact Scientist and Natural
Hazards Coordinator, Met Office
The Vehicle OverTurning (VOT) Model is an innovative tool which aims to forecast the
impact of high winds on the UK road network. Although still being developed, the VOT model
has already been used by operational meteorologists at the Met Office to improve the
understanding of risk on the road network during wind storms and aid decision making in the
issuing of the National Severe Weather Warning Service (NSWWS) wind warnings to the
public. The model uses the high resolution MOGREPS-UK ensemble to generate a
probabilistic risk value for likely disruption to the road network. Forecasts of wind gust speed
and direction from MOGREPS-UK provide a probabilistic hazard value which is then
combined with vulnerability and exposure values to give an overall risk value termed Risk of
Disruption which indicates the severity of road disruption expected should a vehicle overturn.
The model has been developed as part of a Hazard Impact Model (HIM) under the auspices
of the Natural Hazards Partnership, which is a collaboration between 17 UK governmental
agencies. The aim of the HIM is to produce early warnings for a range of natural hazard
events by generating an overall picture of the risk to society, based on probability and
impact. This presentation will illustrate how the VOT model can inform the NSWWS about
the impacts predicted during a high impact weather event and allows meteorologists to make
a more informed decision about the extent and level of the warning to be issued.
Natural Hazards Partnership
Rebecca Hemingway, Weather Impact Scientist and Natural
Hazards Coordinator, Met Office
Established in 2011, the Natural Hazards Partnership (NHP) is a consortium of 17 UK
government departments (including the Welsh and Scottish devolved administrations),
agencies and public sector research establishments. The NHP’s 2020 vision is to be
recognised as”The UK’s trusted voice for coordinated natural hazards advice”.
NHP partners existing natural hazard science, expertise, data and services are shared
amongst the partnership on an ”in-kind” contribution basis, to deliver better coordinated,
quality assured and consistent multi-sector (e.g. health, transport, life and property etc)
impact-based natural hazard advice to responder communities and governments across the
UK. The NHP’s current service offerings focus on the ”Daily Hazard Assessment”, a “onestop shop” overview of natural hazards likely to affect the UK over next 5-days and
coordinated advice provided in support of the UK Government’s 2-yearly national risk
assessment process. Through its science working groups, the NHP is looking to develop
frameworks to enable the integration and visualisation of multiple hazard impact models and
assessments and is also working to identify and highlight natural hazard capability gaps with
a view to informing future research and development priorities.
Realisation of the NHP vision will result in: (i) Better informed mitigation and adaptation
strategies for individual natural hazards and for linked and compounding hazards; (ii)
Increased natural hazard warning lead times with improved assessments of likelihood and
predicted impact, location, type and severity and; (iii) Increased natural hazard data
interoperability and harmonised visualisation strategies.
The importance of climate variability for a weatherdependent power system in Great Britain.
Hannah Bloomfield, PhD Student, University of Reading
Within the power system of Great Britain (GB), there is a rapidly increasing amount of
generation from renewables, such as wind and solar power. An increased proportion of
weather-dependent generation will result in increased power system variability and volatility.
Therefore, an understanding of the impact of climate variability on the power system is
needed to meet with high renewable generation targets. For this study 36 years of
atmospheric reanalysis data (from 1980-2015) are used to construct hourly demand and
wind power time series. These are then are used to create demand-net-wind load duration
curves (LDC's) for the GB power system. Four wind power scenarios (0, 15, 30 and 45 GW)
are used in this study. Four metrics of power system analysis are explored. These are the
interannual range in: the total annual energy requirement of the system (TAER), peak
demand, peaking plant operation and baseload plant operation. The metrics are compared
for each wind power scenario to improve our understanding on the impacts of climate
variability on increasing wind power generation in the GB power system. For the 0GW
scenario, a maximum interannual difference in TAER of 6.9TWh is found (between 1986 and
2007). This difference corresponds to 2.1% of the mean TAER from the scenario. The
interannual spread in LDC's is found to be largest for plants operating at low load factors.
This suggests that interannual climate variability has a disproportionate impact on peaking
plant and peak load requirements. For the 15GW power scenario, the TAER is reduced.
However there is an increase in the amount of interannual variability seen in the TAER of the
system with a maximum difference of 6.2% of the mean TAER value. The increase in
interannual variability is larger for baseload plant than for peaking plant and peak demand.
This result also holds for the 30GW and 45GW wind power scenarios with a maximum
interannual range in TAER of 13.7% of the mean value seen for the 45GW of installed wind
power scenario. The largest interannual differences are found between years of 1990 and
2010, when the wind over the GB was at a maximum and a minimum respectively.
Weather and Climate Education for Youth
Natalie Carroll, Professor, Purdue University, USA
New online curriculum, Weather and Climate Science, was developed for youth education in
informal settings. It includes resources for parents and other educators interested in teaching
these topics. There are three age-graded manuals each with a guide for adult facilitator.
Level 1 introduces basic terms and concepts for youth in grades 4-6 (US grades 3-5). Level
1 focuses primarily on understanding the signs of weather and introduces the difference
between weather and climate. Level 2 activities introduce youth in grades 7-9 to more
complex weather topics, understanding climate, and making and using weather instruments.
Level 3 (grades 10-13) activities are divided into two major sections: weather and climate.
Weather topics include air masses, pressure systems, windchill and heat index, monitoring
weather, and weather station models. Climate topics include climographs, droughts, energy
and energy balance, sunspots, and investigating climate change. Level 3 delves deeper into
weather and climate science concepts to prepare youth to be well informed and to study
these topics at a college or university. The curriculum is available for a nominal charge ($3
for youth books and $2.50 for instructors manual) at Purdue Extension's The Education
Store at www.edustore.purdue.edu. Search for Soil and Water Science. Because the
curriculum is online, users can click on a topic of interest in the table of contents and it will
open in a new webpage. Level 1 curriculum is also available in print for $5.50. Conference
planners are welcome to review the curriculum via Dropbox (http://tinyurl.com/orrmx32).
Climate Change Impacts on Energy Systems – A Review
Jen Cronin, Doctoral Researcher, Doctoral Researcher
The energy sector accounts for approximately 70% of greenhouse emissions and is thus a
major contributor to anthropogenic climate change. However, energy demand patterns and
supply systems are also affected by climate change via a series of positive and negative
feedback mechanisms. Long-term trends in climate variables and increasingly frequent
extreme weather events potentially affect system components such as renewable resources,
power plant efficiencies, biomass crops, water availability for CCS and infrastructure
downtime. These, in turn, can impact energy price, energy security and human welfare. Any
impact which increases GHG emissions thereby acts to increase global warming,
intensifying the feedback cycle. TIAM-UCL is a global optimisation model which designs the
least-cost future energy system within given technological and economic constraints. In
order that this model can make informed decisions about future deployment of energy
conversion and transportation technologies, it is vital that climate feedbacks are included.
Following a critical literature review, this poster describes the current state of our
understanding of this subject. The potential impacts of climate change throughout the energy
system from primary resources to final demand are itemised. To elucidate the relative
importance of the different climate variables, the impacts are shown as a table of climate
variable versus energy system element and the feedback loops between the energy system
and climate are illustrated as a flowchart.
Intercomparison of methods of coupling between
convection and large-scale circulation
Chimene Laure Daleu, Research Scientist, University of Reading
In the past decade, a set of methods of parameterizing large-scale dynamics has offered a
computationally cheap way to study a range of problems in which two-way interactions
between tropical convection and large scale dynamics are essential. One of the methods,
the weak temperature gradient (WTG) approximation is to derive the large-scale circulation
from the assumption that its action counteracts the local buoyancy anomaly and thus,
maintains the horizontal variations of potential temperature close to zero. Another method,
the damped-gravity wave (DGW) is to derive the large-scale circulation directly from the
momentum equation. Much insight has been learned from such studies but however, both
agreement and discrepancies between different studies are seen in the published results.
The GASS-WTG international intercomparison project has been initiated in early 2014. The
project aims to compare the WTG and DGW methods with a consistent implementation in a
number of CRMs and SCMs, and to compare the behaviour of a number of CRMs and
SCMs under consistent parameterizations of the large-scale dynamics. For each model, the
implementation of the WTG or DGW method involves a simulated column which is coupled
to a reference state. The reference state is defined with profiles obtained from the same
model in radiative-convective equilibrium. In Part I, the simulated column has the same sea
surface temperature (SST) as the reference state.
In Part II, the reference state is held fixed while the SST of the simulated column is varied.
Here, we are presenting some of the main differences that have emerged between the
models and methods. For both uniform and non-uniform SST conditions, SCMs display a
wider range of behaviours than CRMs. CRMs show a fairly linear relationship between
precipitation and circulation strength. Within an individual SCM, a DGW simulation and a
corresponding WTG simulation can produce different signed circulation. The DGW
simulations produce large-scale pressure velocity profiles which are smoother than and less
top–heavy compared to those produced by the WTG simulations. Over uniform SST, only a
few models reproduce their own reference solutions, while others sustain a large-scale
circulation which results in either substantially lower or higher precipitation compared to the
value of the reference state. Some SCMs under the WTG method produce zero
precipitation. When initialized with a dry troposphere, DGW simulations always result in a
precipitating equilibrium state. The greatest sensitivities to the initial moisture conditions
occur for multiple stable equilibria in some WTG, corresponding to either a dry equilibrium
state when initialized as dry or a precipitating equilibrium state when initialized as moist. In
some models, the existence of multiple equilibria is sensitive to some parameters in the
WTG calculations. Over non-uniform SST, a large proportion of models shows a non-linear
increases of precipitation with the SST. Few models shows sensitivity of precipitation to the
SST which is not monotonic. The sensitivity of precipitation to the SST differs from one
model to the other and from one method to the other. Some SCMs under the WTG method
with a warm SST produce lower precipitation rate compared to the value of the RCE
reference state. CRMs under both WTG and DGW methods shows a compact relationship
between precipitation rate and column-relative humidity, with the former increasing rapidly as
the latter increases pass a threshold, while SCMs show large deviation from this
relationship.
A Perfect Storm? The collapse of Lancaster’s critical
infrastructure networks following intense rainfall on
4th/5th in December 2015
Emma Ferranti, NERC Knowledge Exchange Fellow,
University of Birmingham
Other Authors: Lee Chapman, Duncan Whyatt
Between the evening of Friday 4th December and early on Sunday 6th December a total of
81.8 mm of rain fell at Hazelrigg weather station near Lancaster University, UK. Indeed the
period from 09:00 on Saturday to 09:00 Sunday was the second wettest 24-hours of any
month in the station’s 50 year history. Moreover the preceding month was the wettest
November on record and the rain fell on already saturated ground. The impact that Storm
Desmond had on Lancaster’s critical infrastructure networks was immense. Around 23:00 on
the 5th December a major substation located close to the River Lune flooded leaving 55,000
properties, the vast majority of Lancaster, without electricity until the morning of 8th
December. The consequences of this power loss cascaded through the city. For example,
non-urgent operations and clinics were cancelled at The Royal Lancaster Infirmary. Without
power, Lancaster University closed for the remainder of the term and schools were closed
throughout the city. The water supply to some homes was impacted when pumping
equipment was unable to operate. The motorway service stations at Lancaster, and
Lancaster train station closed due to power loss. Critical road networks were also impacted.
The two bridges over the River Lune that connect north and south Lancaster were closed
due to safety concerns on the 6th and 7th December, and the exit slip road northbound and
southbound from M6 motorway were closed on 5th and 6th December due to flooding. Other
key local roads and sections of the city’s one-way system were also impassable due to
flooding. Lancaster’s critical infrastructure networks collapsed between 5th and 8th
December. But was this the perfect storm, or an indication of things to come? Extreme
rainfall events are expected to become increasingly common the forthcoming century and by
2040 86% of the UK population will live in cities. Cascade failures such as that witnessed in
Lancaster are particularly problematic in urban areas which combine dense populations of
people and highly-evolved, interdependent critical infrastructure. Much of Lancaster’s critical
infrastructure depended on one substation in an area of known flood risk and in order to
prevent similar events in the future the supply network needs to more flexible. More
generally there must be cross-disciplinary co-ordination between infrastructure operators
and users, local authorities, and specialist organisations such as the Met Office and
Environment Agency in order to facilitate a whole systems approach to build our cities’
resilience to extreme weather in the future.
Intelligent pricing plans for de-icing companies
Helen Fox, Scientist, Met Office
De-icing companies are on standby throughout the Winter period to provide surface
salting/gritting to their customers (e.g. retail parks, industrial estates, private roads and
hospital grounds). When forecasted or observed road surface temperatures (RST) fall below
a certain threshold (varies for each company) and/or road surface conditions unfavourable to
ice formation occur de-icing companies begin their gritting activities. Many cover wide
ranging areas of the UK that experience varying meteorological conditions. Latitude, altitude,
topography, distance from the coast and urban-heat island influences are amongst the key
factors that influence the climatology of the UK. As customer demand moves towards
requiring fixed-price service plans, de-icing companies require advanced insight, prior to the
winter season, to provide intelligently derived prices for their services in order to avoid
substantial losses whilst also remaining competitive. We use 8-years of meteorological data
from the OpenRoad network to construct long-term climatologies (e.g. days of RST below 2,
1, 0, -5 degrees C and road surface conditions (e.g. days of snow cover)) for across the
whole of Great Britain, with the aim of providing postcode level detail.
Lost in translation? Severe weather events and climate
change training for industry and stakeholders
Dr Rebecca Griffiths & Mike Mason, Senior Climate Science
Training Consultant & Industry Training Manager, Met Office
College, Met Office
Other Authors: Mike Manson
Portraying scientific uncertainties associated with both weather and climate events to inform
decision-making, presents a unique challenge for communicators. It is widely acknowledged
that there is something inherently complex about the nature of understanding weather and
climate events and the scale of impacts on society. Yet, establishing a heightened risk
perception to potential weather and climate impacts is imperative to preparing industry
services or developing livelihood resilience, both through informing the decision-making
process by stimulating adaptive change. This will demonstrate applications for improving risk
resilience to weather and climate through providing industry training to key stakeholders both
within the UK and internationally. It will explore different approaches to improve risk
perceptions of extreme weather and climate change impacts, alongside key barriers to
effective communication of climate science to inform decision-making.
The Met Office College has been delivering weather and climate training within the UK and
internationally for over 15 years. Experiences will be drawn from delivering training to a
range of different sectors and purposes including: agricultural extension, research institutes,
policy makers, road and rail, utilities, and the emergency response community alongside
continued support for international development of met services. Such training focuses on
the accurate interpretation of forecast products (warnings and hazard manager including
synoptic charts, severe weather warnings, Firemet, CHEMET, as well as storm surge
ensembles) and future climate predictions, that will enable planners to scan the horizon and
make more educated decisions. Examples will be drawn from delivering training on courses
such as: Managing High Impact’ Weather at the Emergency Planning College’, designed to
help members of the emergency planning community develop a better insight into what
causes severe weather and how a forecaster operates. From the delivery of such training, it
is apparent that understanding weather and climate terminology will improve communication
between responders and Public Weather Advisors during an event. Furthermore, key
barriers to effective communication of weather and climate impact events have been
identified and overcome throughout our training. For example, a perceived distance in time
and place of a event happening, misinterpretations of uncertainty inherent to weather
forecast and climate prediction models, mixed messages from the media, a lack of locally
relevant examples of possible impacts, and a lack of relevance of weather and climate
science to industry specific or local knowledge.
As with most things in life the communication of the message is primary, this is not just with
the climate or weather service provider but also with internal colleagues, other agencies and
the general public. Most organisations such as those within the emergency response or
industry sectors will need to translate and pass the ‘Met’/climate message on and be able to
ask informed questions of forecasters. To conclude, recommendations to overcome key
communication barriers to improve industry perceptions of high impact weather and climate
events through the successful delivery of training will be made through discussion of case
studies from industry training.
Vocabulary services to support climate research and
climate data exploitation
Martin Juckes
Other Authors: Phil Kershaw, Ruth Petrie, Rob Thomas, Antony Wilson
The Centre for Environmental Data Ananalysis (which hosts the British Atmospheric Data
Centre and other data centres) is developing a system for managing vocabularies describing
climate data which will improve a range of archive services. The system is being developed
in the context of three large projects: the FP7 Climate Information Platform got Coperincus
(CLIPC) project, the ESA Climate Change Initiative Portal and the CMIP6 Data Request.
This poster will decsribed the role of vocabularies in these projects and the approach being
developed in collaboration with the British Oceanographic Data Centre (BODC), based on
the existing NERC Vocabulary Service which is run by BODC. The system makes use of the
Simple Knowledge Organisation System (SKOS), a World WideWeb standard for
representation of vocabulary terms and the relationships between terms. The use of SKOS
gives each term a unique identifier which can be used throughout the data services to
improve robustness and transparency of data management. In particular, it will allow better
integration between catalogues and advanced search services used for browsing extremely
large archives.
Teaching livestock producers and extension agents about
impacts of extreme weather and changing climate on
agricultural production
Pamela Knox, Agricultural Climatologist, University of Georgia
Livestock are affected by both short-term weather extremes like heat waves and long-term
climate events such as droughts. Climate change is expected to make these extreme
events more frequent, causing significant negative impacts on agricultural production. A 15hour online video-based self-paced course was developed to help farmers and university
extension agents understand the science of changing climate and the impacts of extreme
weather and climate on animal health and production. Modules address basic climate
science as well as climate change impacts on cattle, swine, and poultry. They also describe
how production could be modified to mitigate greenhouse gas emissions and to adapt to
changes in the frequency of severe weather events such as heat waves as well as droughts
and floods. Information on the course is available at http://www.animalagclimatechange.org.
Since the course was first offered in 2012, almost 400 people have registered for the course
and 121 have completed the full 8-module course, with a number still in progress. Course
participants include extension agents and other government employees from the United
States, agricultural producers, agro-business workers, and international scientists and
producers from 21 different countries.
An Assessment of the Resilience of the British Railway
System to an Extreme Hot Weather Event (1st July 2015)
Susan E. Lee, Research Fellow, University of Birmingham
Other Authors: Lee Chapman, Emma Ferranti, David Jaroszweski, Andrew Quin
Over the last few years the UK has been subject to a number of extreme weather events
which have included many severe storms.These events have led to widespread flooding
especially in areas around the Thames, the Somerset Marches, South-west England as well
as coastal stretches of Eastern England and the Lake District. There have been a number of
fatalities and major disruption to the transport system. In addition, there have been several
hot weather events that have also led to travel disruption but are not always as well
publicised. This paper will focus on the transport disruption which occurred on the hottest
July day ever recorded in the UK (maxium temperature of 36.2OC recorded at Heathrow
Airport). Data from the railway industry for that day, and the days leading up to and following
the event, are presented. Specific areas where there was major disruption attributable to the
heat are shown. In addition, areas where there was disruption caused by lightning and heavy
rain in the same period are also presented. Results show that the 30th June and 1st July
recorded the highest number of daily incidents for 2015 and performance was less than 80%
on both days. Disruption was particularly bad between London and a number of major
Scottish cities. The UK railway system’s resilience to the heat is assessed and suggestions
as to potential future solutions to the issues raised are presented.
Recalibration of extreme model gust speeds using
observations
Lorna Mitchell, Applied Scientist, Met Office
Recalibration of extreme model gust speeds using observations European windstorms are
capable of producing devastating socioeconomic impacts and are a significant risk to the
insurance industry. For example, the windstorm Kyrill in 2007 caused $10.0Bn and Xynthia
in 2010 caused $6.6Bn worth of damage. A high-resolution (4km) European hindcast is used
to validate model gust speeds with observations for the most damaging European
windstorms. Model gust speeds are found to verify well with observations under 25m/s, but
to flatten off above that threshold showing that the model under-predicts the strongest gust
speeds. It is these strongest gust speeds that cause the greatest damage and it is therefore
important that they are accurately modelled. The damage caused by a storm is related to the
cube of the gust speed. This suggests that it is desirable to recalibrate model gust speeds
with observations. The recalibration is applied in two steps. First, a Generalised Additive
Model (GAM) is applied which assumes a smooth, non-linear statistical relationship between
model and observed gust speeds. This relationship is allowed to vary with latitude and
longitude to account for spatial variability in the observations which are not captured in the
model. Secondly, a Cumulative Distribution Function is determined between the strongest
observed and modelled gust speeds. Verification of the recalibrated model gust speeds
against observations show that the recalibration technique is beneficial and significantly
improves model gust speeds, whilst maintaining the overall structure of storms.
The Air Quality Expert Group - Communicating your
science to policy-makers
Sarah Moller, NERC KE Fellow & NCAS Research Scientist, NCAS,
University of York
The Air Quality Expert Group (AQEG) is an Expert Committee to Defra that provides the
Department and Devolved Administrations with independent, expert advice on air quality
science, including the sources, behaviours, levels and mitigation options for key air
pollutants. This advice forms an important part of the evidence base underpinning air
pollution policy. AQEG deliver much of their advice through comprehensive reports and
advice notes, which requires them to analyse, interpret and synthesise relevant research
published by the atmospheric science research community. AQEG represents an important
mechanism for the communication of air pollution research to policy-makers. This poster will
present AQEG and the work that it does. Discussion is welcome around how AQEG
represent the atmospheric research community, how your research could end up on the
agenda, how topics of reports are decided and other related areas. AQEG will be recruiting
in early 2017; discussions about this, such as what is expected of AQEG members, are also
welcomed.
Statistical Analysis of Future Projections of Extreme Winds
for Current Infrastructure Planning
Stephen Outten, Researcher, Nansen Environmental and Remote
Sensing Centre
Every year, extreme winds cause vast amounts of damage that represents a major concern
for numerous industries including construction, insurance, afforestation, wind energy and
many others. A critical component of climate change adaptation is to improve our
understanding of extreme events and to estimate how their frequency and magnitude are
likely to vary in the future. Accurate projections of these changes will be invaluable to
decision makers and to society as a whole. Extreme winds over Europe have been
estimated using a peaks-over-threshold method and the Generalized Pareto Distribution
(GPD) to obtain the projected change in the 50-year return wind, along with the associated
uncertainties. This was done for four downscalings from the ENSEMBLES project – the DMI
and SMHI downscalings of both the Bergen Climate Model and the ECHAM5/MPI-OM
coupled GCM. This approach allowed for an inter-comparison of the extreme wind between
different GCM-RCM combinations. It was found that for most of Europe the change in the
50-year return wind projected by the models was smaller than the uncertainty associated
with the statistical estimation of such a rare event; and far smaller than the inter-model
spread in the 50-year return wind. Large-scale construction projects often require an
assessment of extreme winds, which is based only upon the historical observations of wind,
when the climate was approximately stationary. Under a changing climate, infrastructure
built to last for the next fifty years or more may experience events not seen in the
observational period. A case study is presented for the new Hardanger Bridge in Norway
that demonstrates one novel method for incorporating estimates of future changes in
extreme winds into the design process. Given the close collaboration with the engineers
involved in the bridge’s construction, the method was tailored to fit with existing practices
and standards. The potential to develop this method into a simple climate service will also be
discussed.
Fixity Checking a Large Climate Data Archive
Samuel Pepler
Climate science and Earth Observation rely on large data sets. The Centre for
Environmental Data Analysis has an archive of over 2PB of data. In terms of data volume
the bulk of the data is the output from climate models and numerical weather prediction
systems, and earth observation datasets. In an archive context it is important to make sure
that any changes to the data are expected and not the result of IT systems corrupting data
files. As data comes into the archive the default is to not allow data to be overwritten. Where
overwrite is permitted file modification times are updated. Very occasionally data files have
been seen to change their content with no corresponding update of the modification time.
These corruption events are systematically looked for within the CEDA archive so that timely
recovery from backups can be made. The effect of corrupt files varies with the extent of
corruption and the types of file affected. Where compression techniques are used whole file
can be rendered unusable. Corrupt files can disrupt scientific processing runs that are
expecting consistent well-formatted data. This poster explains the processes used to
periodically checksum the archive, including tracking of audit tasks in a database,
parallelising checksumming operation on a cluster and the recording of corrective actions.
Conclusions are drawn about the frequency of corruption events and the likely causes.
Past extreme hydrological events in the UK through the
lens of documentary proxy records
Marie-Jeanne S. Royer, Post-doctoral Research Associate,
Aberystwyth University
Other Authors: Sarah Davies, Cerys Jones
In the UK, climate change research has underlined the need for a robust understanding of
hydrological events and their impacts on communities and individuals. Targeted mitigation
and adaptation strategies can be developed using long term data on the frequency, intensity
and impacts of these events in conjunction with climate change projections. Documentary
proxy records can be employed to identify and qualify extreme hydrological events and
utilised in conjunction with instrumental data can provide more detailed information on the
impacts of such events than instrumental data alone (e.g. daily precipitation, if available, can
be an unreliable indicator of a flood event). This paper targets three UK case study regions
(i.e. Wales, East Anglia Coast, Central England) based on DEFRA’s 2012 ‘Climate Change
Risk Assessments’ for the UK. A systematic search through available archive records was
conducted to identify flood proxy records for these regions. We then proceeded to undertake
a content analysis of these documented flood events and to compare them to known flood
events from other sources. Preliminary results indicate a link between benchmarking and the
identification of extreme hydrological events. Through this approach we hope to identify
events that had severe consequences on the impacted communities (e.g. death, destruction
of property) even if they may have been less significant instrumentally.
Build Your Own Earth: Exploring Climate Model Output for
Teaching and Research
David M. Schultz, Professor of Synoptic Meteorology,
Other Authors: Stuart Anderson, Jonathan Fairman, Sharon Gardner
Build Your Own Earth was a vision that we had to engage students in understanding the
controls on Earth’s climate. The vision was for students to build their own worlds by
selecting various characteristics of a planet: distance from the Sun, tilt of the axis, location of
continents, oceans and mountains, rotation rate, atmospheric composition, etc. Students
would enter these characteristics on a web page, and then, after pushing the “Go” button, a
climate model would run in the background and produce the climate on that world.
Unfortunately, such a vision is not possible with the speed of today’s computers. Even using
a simplified climate model built for speed (FOAM: the Fast Ocean-Atmosphere Model) and
with coarse resolution (each atmospheric grid box is 7.5° in longitude and 4.5° in latitude),
our supercomputer will only run about 480 years of model climate in one day. Each model
planet needs about 50-300 years of simulations to obtain a stable climate. Plus, with
thousands of students submitting simulations in real time, our supercomputer would be
inundated with requests. Instead, we preselected about 50 Earths, did the computer
simulations already, and prepared plots of the simulation results for students to explore on
BuildYourOwnEarth.com.
Earths are in three categories: Recent, Ancient, and Alien.
Recent Earths include a Current Day (2015) simulation with 400 ppm carbon dioxide. We
also have a preindustrial control simulation, a simulation from 1975, and a simulation with no
greenhouse gases. We also have simulations where we’ve changed the carbon dioxide
concentrations (including some from our possible future), the amount of solar radiation
received by the Earth, and orbital parameters of the Earth (axial tilt and eccentricity).
Ancient Earths include snapshots from the past such as the Last Glacial Maximum (21,000
years ago), Miocene, Jurassic, Triassic, Carboniferous, Cambrian, and Ediacaran. Because
the atmospheric carbon dioxide and methane concentrations are not well constrained, there
is some uncertainty. Thus, we encourage students to not read these simulations as literal
pasts, but as explorations of what changing ocean and land configurations can do to the
climate when placed under the constraint of constant atmospheric composition. Alien Earths
abstract the climate down to its essence. What is the effect of no continents on Earth
(Aquaplanet)? What would the circulation look like during Snowball Earth (Iceplanet, which
would be very much like Hoth from The Empire Strikes Back)? What would happen if we
had a single continent on the equator? Or on the pole? What if the whole Earth was land
except for a single ocean in the middle?
Build Your Own Earth was developed for the University of Manchester Coursera course “Our
Earth: Its Climate, History, and Processes”;, but will be implemented as a homework
assignment and feature of the lecture content in the introductory Earth science course in the
first semester of the next academic year. We also anticipate that the content will make
excellent fodder for undergraduate research projects. The website is freely available for all to
access and use.
ManUniCast: A Community Weather and Air-Quality
Forecasting Teaching Portal
David M. Schultz, Professor of Synoptic Meteorology,
Other Authors: Stuart Anderson, Jonathan Fairman, Elsa Lee, Douglas Lowe,
Gordon McFiggans, Ryo Seo-Zindy
Manunicast was borne out of the needs of our teaching program: students were entering a
world where environmental prediction via numerical model was an essential skill, but were
not exposed to the production or output of such models. Our site is an educational testbed to
explain to students and the public how weather, air-quality, and air-chemistry forecasts are
made using real-time predictions as examples. As far as we know, this site provided the first
freely available real-time predictions for the UK. We perform two simulations a day over
three domains using the most popular, freely available, community atmospheric mesoscale
and chemistry models WRF-ARW and WRF-Chem: 1. a WRF-ARW domain over the North
Atlantic and western Europe (20-km horizontal grid spacing) 2. a WRF-ARW domain over
the UK and Ireland (4-km grid spacing, nested within the 20-km domain) 3. a WRF-Chem
domain over the UK and Ireland (12-km grid spacing) Called ManUniCast (Manchester
University Forecast), we offer a suite of products from horizontal maps, time series at
stations (meteograms), skew-T-logp charts, and cross sections to help students better
visualize the weather and the relationships between the various fields more effectively,
specifically through the ability to overlay and fade between different plotted products.
Spaces of Experience and Horizons of Expectation':
Extreme weather in the UK, past, present and future
Lucy Veale, Research Fellow, University of Nottingham
Other Authors: James Bowen, Sarah Davies, Georgina Endfield, Cerys Ann Jones,
Neil Macdonald, Simon Naylor, Marie-Jeanne Royer
The UK is accustomed to variable weather, but recent weather events have increasingly
been framed as “unprecedented”. Our multi-institution project places recent events within an
historical context and demonstrates that extreme weather is by no means a new
phenomenon. This poster will focus on our investigations of the historical geographies of
extreme weather events in a series of case studies across the country. Drawing on
documentary evidence based in a wide range of county, regional and national archives,
together with oral history material, we investigate the timing and impacts of and responses to
past weather events dating back to the late seventeenth century and consider the way in
which events become recorded, in what form and by whom. We explore the processes by
which certain events become inscribed into cultural memory as ‘extreme’, while others are
forgotten, highlighting the importance of spatial and temporal contingency in these
processes. We will also showcase the development of our online database of extreme
weather events in the UK (TEMPEST), which can be interrogated to explore (and map) the
impacts of, and responses to extremes and to search observer biographies.
Evaluation of the response and spatial variability of wind
speeds and directions in Ireland to the NAO, the EA and
the SCA based on a dynamically downscaled dataset
Laura Zubiate, PhD student, University College Dublin
The 3 hourly resolved gridded ERA-Interim climate reanalysis dataset was used to
investigate the spatial stationarity of the previously documented relationship between wind
speeds and the NAO state in Europe. In much of Western Europe, wind speeds were found
to be affected strongly by the concomitant states of the secondary and tertiary atmospheric
teleconnections, namely the East Atlantic (EA) and the Scandinavian (SCA) patterns. These
modify the geographic position of the NAO dipole and modulate the influence of the NAO on
wind statistics on regional scales, producing non-stationarities in the NAO-wind speed
relationships. A systematic North-South shift in the Weibull distribution scale and shape
parameters along the western margin of Europe is documented, depending on the states of
the NAO, the EA and the SCA. The results have implications for regional to continent-scale
long-term planning of windfarm siting to minimise the impact of resource intermittency.
Finally, in order to study these effects on wind speeds and wind directions, combined with
topography at a local level, a dynamical downscaling of the aforementioned ERA-Interim
dataset was performed using the WRF free software. The output of this downscaling is a 3
km resolution dataset for the whole island of Ireland, comprised of 199 atmospheric
variables at 30 vertical levels and hourly resolution, plus time series of selected variables at
model time step at 18 locations in the Republic of Ireland. Wind speeds and directions at 4 of
these locations have been validated against wind mast observations, showing a significantly
improved skill over the original ERA-Interim data.
A comparison of very short-lived halocarbons (VSLS)
aircraft measurements in the Tropical West Pacific from
CAST, ATTREX and CONTRAST
Jamie Minaeian
Other Authors: Stephen J Andrews, Lucy Carpenter, Eric C Apel, Elliot Atlas, Valeria
Donets, James F Hopkins, Rebecca Hornbrook, Alastair Lewis, Richard Lidster,
Richard Lueb, Maria Navarro, Shalini Punjabi, Dabiel Riemer, Susan Schauffler
We present a comparison of aircraft measurements of halogenated very short-lived
substances (VSLS) and dimethyl sulphide (DMS, C2H6S) from a co-ordinated campaign in
Jan/Feb 2014 in the Tropical West Pacific. Measurements were made on the NASA Global
Hawk, NCAR GV HIAPER and FAAM BAe146 using four separate GC-MS instruments
operated by the University of Miami (UoM), the National Centre for Atmospheric Research
(NCAR) and two from the University of York (UoY), respectively. The UoY airborne GC/MS
is a new instrument for measuring airborne species, and therefore was carefully compared to
other, more experienced instruments. Comparisons of vertical profiles indicate a very good
agreement across the platforms, with the exception of the UoY WAS system, which showed
a slight negative bias, attributed to sampling line losses during the campaign. Additionally,
over the region surveyed, it is apparent that the Tropical West Pacific shows extremely low
spatial and temporal variability. These results are encouraging for global flux estimates, in a
region previously lacking in comprehensive datasets.
Linking Human Health and Wellbeing with Weather,
Climate and the Environment
Lora Fleming
Other Authors: Brian Golding, Harriot Gordon-Brown, Shakoor, Gordon Nichols
Introduction: A large part of the global disease burden can be linked to environmental
factors, underpinned by unhealthy behaviours. Research into these linkages suffers from the
lack of common tools and databases for investigations across many different scientific
disciplines to explore these complex associations. The MEDMI (Medical and Environmental
Data -a Mash-up Infrastructure) Partnership brings together leading organisations and
researchers in climate, weather, environment, and human health and wellbeing.
Methods: We have created a proof-of-concept central data and analysis system with Office
and Public Health England (PHE) data as the internet-based MEDMI Platform (www.datamashup.org.uk) to serve as a common resource for researchers to link and analyse complex
meteorological, environmental and epidemiological data in the UK. The Platform is hosted on
its own dedicated server, with secure internet and in-person access with appropriate
safeguards for ethical, copyright, security, preservation, long-term accessibility and data
sharing issues. Via the Platform, there is a demonstration Browser Application with access to
user-selected subsets of the data for: a) analyses using time series (e.g. mortality and
environmental variables), and b) data visualizations (e.g. infectious diseases and
environmental variables). One demonstration project is linking climate change, harmful algal
blooms (HABs) and oceanographic modelling building on the hydrodynamic-biogeochemical
coupled models; in situ and satellite observations as well as UK HAB data and hospital
episode statistics (HeS) data are being used for both model verification and future
forecasting.
Conclusions: The MEDMI Project provides a demonstration of the potential, as well as a
better understanding of the barriers and challenges, of these “data mashups” of environment
and health data. Although there remain many challenges to creating and sustaining such a
shared resource, these activities and resources are essential to truly explore the complex
interactions between climate and other environmental change and health at the local and
global scale.
Tropical Cyclones in A High Resolution Regional Climate
Model
Ju Liang
Other Authors: Kevin Hodges, Chang Gui Wang
Every year Tropical cyclones (TCs) cause large economic losses and loss of lives across the
coastal area of the western North Pacific (WNP). It is therefore important to better
understand their climatology and variability. This is often done with numerical models.
However, due to the complex structure and energetic processes of TCs, high model
resolutions are required to simulate them correctly. This study aims to simulate TCs over the
WNP using a high resolution regional climate model (RCM) of the Met Office Unified Model
with model resolutions of 25km and 12km. The lateral boundary conditions of the RCM are
provided by the ECMWF ERA-Interim reanalysis data and HadGEM2-ES global climate
model (GCM). TCs are identified in both simulations and compared with observed TCs
(IBTrACS) to show the potential of improving the simulation of TCs in an RCM with
increased resolution. The result shows that the 25km and 12km models can correctly
simulate the TC-associated large-scale environments, while the 12km model has better skill
in simulating the South Asian monsoon compared with the 25km model. The distributions of
TC genesis and track are correctly simulated in both the 25km and 12km model. Compared
with the 25km model, the 12km model improves the simulation of track density. However, for
TC intensity, the 12km model did not generally produced stronger 10m maximum wind
speeds near the TC center, which is possibly due to the shift in the location of TC wind a
maximum maxima towards high topographic regions. For the downscaled GCM simulation
during 1961-2005, the model can capture the enhanced (weakened) TC activity during La
Niña (El Niño) events. The simulated TC intensity is also weakened (enhanced) by La Niña
(El Niño) events, which are consistent with the observations.
New analysis and visualisation tools: cf-python and cfplot
Charles Roberts, CMS Software Engineer, NCAS
Other Authors: David Hassell, Andrew Heaps, Bryan Lawrence
cf-python is a python package which creates, reads, writes and manipulates data and its
metadata. It is fully compliant with the Climate and Forecast (CF) metadata conventions
(v1.5) and can read data stored in CF-NetCDF and both Met Office (UK) PP and fields
format files. When reading, it is not strict in enforcing the CF conventions, supporting the
reading of files that are not fully CF-compliant, allowing the subsequent addition of CFcompliant metadata as necessary. cf-python supports metadata aware data operations
including basic arithmetic and statistics as well as more complex regridding using the highperformance Earth System Modelling Framework (ESMF) regridding library.
cf-python operations are not memory limited as memory handling via the Large Amounts of
Massive Arrays (LAMA) functionality allows multiple fields larger than available memory to
be manipulated without any extra work by the user.
cfplot is a python package built on cf-python that uses the metadata in a CF field to create
an appropriate contour or vector plot. It can also do line plots. The package allows easy
control of colour tables and plot positioning. By default the colour maps used are
perceptually uniform, which means that the perceived intensity of the colours varies linearly
with the numerical scale. cf-view provides a simple GUI interface to basic cfplot functionality.
Both cf-python and cfplot are metadata-aware, meaning that they make full use of a field’s
metadata (such as which axes it has) to simplify the analysis, and all operations preserve
metadata. For example, cf-python and cfplot will automatically determine which axes of a
field correspond to the latitude and longitude coordinates from the field’s metadata.
Consequently operations such as regridding a field to the grid of another field, which would
be relatively complex, can be performed in a single line, and output data retains input
metadata.
cf-python and cfplot are available on bitbucket, pypi, and as conda packages.

Book of Abstracts - Royal Meteorological Society

Transcription

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Alexander Palmestål Portfolio 2016 alexanderpalmestal.com

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