1. Introduction

NRT Core
Services
Ad.Stoffelen@knmi.nl
KNMI scatterometer
team scat@knmi.nl
Vongfong, 8 October 2014
Outline
Scatterometer wind services
Nowcasting
Global NWP
Regional NWP
Satellite Wind at Sea Services
NWP SAF software users
•
•
•
•
24/7 Wind product services (OSI SAF)
– Constellation of satellites
– Africa
High quality winds, QC
– China
Timeliness 30 min. – 2 hours
– Europa
Service messages
India
– Other
QA, monitoring
Asia
Russia services (NWP SAF)
Software
America
– South
Portable
Wind Processors
USA
– Weather model comparison
Organisations involved:
KNMI, EUMETSAT, EU, ESA, NASA,
NOAA, ISRO, SOA, WMO, CEOS, ..
Users: NHC, JTWC, ECMWF, NOAA,
NASA, NRL, BoM, UK MetO, M.France,
DWD, CMA, JMA, CPTEC, NCAR, NL, . . .
More information:
www.knmi.nl/scatterometer
Wind Scatterometer Help Desk
Email: scat@knmi.nl
What we do, R&D
• Help build a constellation for increased temporal
coverage
• Cal/val, NWP ocean calibration, e.g., OSCAT, HY2A,
ASCAT-B, RapidScat
OSI SAF Wind Products
ASCAT-A 25-km winds
• QC, e.g., QC near rain (AS Marcos Portabella)
Operational status
ASCAT-A 12.5-km winds
status
• First VH GMF in extreme winds to support Operational
EPS-SG
ASCAT-A
coastal winds
Operational status
25-km winds
• Analysis of C-band GMF at extreme winds ASCAT-B
Operational status
ASCAT-B coastal winds
Operational status
• First analysis of structures at sea
Oceansat-2 winds
Discontinued status
QuikSCAT winds
• Increased resolution (EUM NWP SAF)
Discontinued status
Wind Products Processing Status
• FA with EUMETSAT and Un. Vienna on “coastal”
soil
Other Wind Services at KNMI
ASCAT-A 25-km winds (EARS)
moisture
Operational status
ASCAT-A 12.5-km winds (EARS)
Operational status
• CDR sampling error
ASCAT-B 25-km winds (EARS)
Operational status
ASCAT-B 12.5-km winds (EARS)
• Stress-equivalent winds (EU MyOcean)
Operational status
4
www.knmi.nl/scatterometer
scat@knmi.nl
OSI SAF User Workshop | November 2014
ERS-2 winds (EARS)
Discontinued status
Scatterometer work at KNMI
RapidScat
Mounted last
week!
Data in 2015
(Copernicus)
www.jpl.nasa.gov/news/ne
ws.php?feature=4325
OceanSat-2
scatterometer
OSCAT
International
collaboration and
lead cal/val team
 Exchange of resources, support
to increase temporal sampling
 Winds at ~12 and ~00 LST
HY2A
Scatterometer
Evaluation
Ad.Stoffelen@knmi.nl
Anton Verhoef




Same approach as for OSCAT
Data exchange
Offer expert and GS support
At ~6:00 and ~12 LST
Independent Verification
• Compare products
with other producers
• Product improvements
• Standards (speed
scale)
Naoto Ebuchi, Tokai Un., Japan
coaps.fsu.edu/scatterometry/
meeting/past.php#2013
OSI SAF User Workshop | November 2014
F
ASCAT High
Resolution
Processing
Workshop
M
A
MetOp
•
Investigate ASCAT Spatial
Response Functions, SRF
•
Detect structures
•
Improve knowledge of aggregated
SRFs for geophysical processing
Ad.Stoffelen@knmi.nl
Stress-equivalent wind
U10N: equivalent-neutral 10m wind
For the same U10N, cold heavy air will produce more stress (and
roughness) than lighter warmer air. This effect is expressed by the
surface stress equation. The surface wind stress τ = ρ u*2 indeed
depends on the air density ρ. Assuming that σ 0 measurements are
more a measure of τ than U10N, the ρ correction for U10N takes
the form
where U10S denotes the current set of stress-equivalent
scatterometer wind retrievals and <ρ> is the average air density as
defined in a standard atmosphere (≈1.225 kg/m3). ρ variations,
which depend on surface pressure, air temperature, and humidity,
are generally small (1-2%) and can exceptionally increase locally in
cases such as cold air outflow.
Hurricane wind extremes
 Discussion on highest ever peak
winds from tyfoon Haiyan in the
media, but impossible to measure!
 Maximum 1-minute sustained winds
are difficult to know, but used for
category!
 Scatterometer winds are mentioned
in 20% of ALL NHC TC discussions
 Scatterometers measure 25-km scale
winds and are thus much lower
extremes than 1-minute peak winds
 Current scatterometers either capture
rain and/or saturate at 40 m/s;
 The impact of a hurricane surge is
catastrophic and depends on wind
speed, wind direction, wind duration
and wind fetch, less on maximum 1minute peak wind (Sandy)
TC Rita
ASCAT hits on Vongfong
50
ASCAT B
ASCAT A
40
30
710
-1
4
710 00:
12
-1
4
710 12:
03
-1
4
710 12:
51
-1
4
810 23:
51
-1
4
910 00:
42
-1
4
910 12:
09
-1
4
13
:0
3
20
 Peak around midnight on 7/8
October 2014 of 42 m/s
(150 km/h)
 ASCAT-A appears low as
compared to ASCAT-B
 Current calibration bias B-A of
0.1 dB (0.1 m/s)
 Required accuracy is 0.2 dB
 Due to GMF saturation, 0.1 dB
at 40 m/s is 4 m/s !
 For extremes more careful
instrument calibration is needed
Trends in extreme wind speed
Trend in 90th Percentile
QuikSCAT
Trend in Wind Speed (in 0.1 m/s per 10 year)
Figure by Jason Keefer and Mark Bourassa, FSU
 Controversy in
trends of mean
and extremes
 Wentz, F. J., and L.
Ricciardulli, 2011,
Science
 Young, I. R., S.
Zieger, and A. V.
Babanin, 2011:
Science
 QuikScat CDR:
unexplained 0.1 m/s
decadal falling trend
of mean wind ?
Go out there!
Key
Flight level
PS dropsonde
With the NOAA hurricane hunters
Time (UTC)
SFMR WS
Feb 4, 2010
HF drops
HF SFMR
High Winds Research
• validation set for remotely sensed winds
•ASCAT, OceanSat-2, future instruments
• NWP forecast models
• Instrumentation
•GPS dropsondes, Step Freq. Mirowave Radiometer
UMASS
Imaging Wind AGU
andOcean
Rain
Air-borne
Profiler
(IWRAP)
Feb•23,
2010
Sciences
2010, Portland,
OR
14
SFMR versus ASCAT
Distance to centre [km]
Distance to centre [km]
 CMOD5 winds are lower than SFMR (VV pol)  add ln(VASCAT)
 However, CMOD5 winds equal buoy winds for 15 to 20 m/s;
which to trust?
 SFMR winds go up when it rains  -ln(RR); NOAA is recalibrating
Calibration strategy
1. GPS dropsondes provide true measure of
local wind
2. GPS dropsondes calibrate SFMR on its
basic footprint
3. Calibrated SFMR data are integrated over
a scatterometer WVC length to provide a
resource for satellite scatterometer
calibration
 Error attribution in all steps
CEOS Virtual Constellation
http://ceos.org/ourwork/virtual-constellations/osvw/
Winds when it matters
high
water
Delfzijl
 0.5 m underpredicted surge
(NL)
by HiRLAM (blue) and
ECMWF winds (green)
 OSI SAF QuikScat winds
(red) are stronger and/or
more directed into the
harbour
 NRT needed
 R&D on mesoscales
needed
1/11/’06 4:03
1/11/’06 6:14
Requirement for visualisation
14:42Z
Weersverwachtingen worden steeds beter
NH
ZH
 Beter gebruik van waarnemingen
 Grotere computers
 Verbeterde weermodellen
21
Substantial NWP Forecast Error
Reduction by Scatterometers
The
sensitivity
to observations
measures
the impactto
of the
observations on the short-range forecast (24 hours).
• forecast
Great
success
of OSCAT;
grateful
ISRO
The forecast sensitivity tool developed at ECMWF computes the Forecast Error Contribution (FEC) that is a measure (%)
Much ofinformation
inthrough
datathe
assimilation;
only
a assimilated
few % observations.
used
of •the variation
the forecast erroris
(aslost
defined
dry energy norm) due
to the
May 2013 versus May 2012
12% Smaller Global FcError
2% FcError Reduction due to GOS
[C. Cardinali ]
OSI SAF User Workshop | November 2014
From plume to probability
eSurge UCM3 2015
Improve meteorology?
Greg.J. Tripoli, Un. Wisconsin
Why high resolution?
Example: Simulation of a storm in 1990
HARMONIE
ERA-Interim
High resolution modelling affects more
than just the coastal zone Baas and De Waal, 2012
25
from R. Boers, KNMI
WMO CGMS International Winds Working group
• See also https://groups.ssec.wisc.edu/groups/iwwg/activities/high-resolutionwinds-1/nwp-data-assimilation
Relevant scatterometer splinter group actions:
• All: Share experimental results among participants. Further experiments on
timing errors, thinning, more aggressive QC in inner/outer loops and
background error structure are encouraged.
• NWP SAF (KNMI): Investigate 2DVar sensitivity to: timing errors, thinning,
QC, background error structure, background (provided by participants) with the
aim to provide guidance to NWP centres.
• NWP SAF: Make above points more prominent on web site: bias correction
guidance, guidance, data and tools (as is) on spatial/spectral analyses and triple
collocation.
• NWP SAF: Organize NWP SAF workshop on scatterometer data assimilation.
HARMONIE WW, 13-16/10/2014, Santander
NRT Core Storm Service
 Provides basic underlying information
when alarm codes turn red
 Real-time for deterministic nowcasting
 Satellite winds are successfully used in
global NWP; global NWP provides
probabilistic ensemble forecasts
 Use of satellite winds is challenging in
regional NWP; coordinated effort in IWWg
 Consistent provision of core winds, waves
and surges for Disaster Risk Reduction in
a one-stop shop?
 Both observations and models?
 One-stop shop portal?
www.storm-surge.info
Haiyan