A41G-‐0053 - 2016 AGU Fall Meeting

A41G-­‐0053 ARM Value-­‐Added Products for the New Scanning and Zenith-­‐PoinAng Cloud Radars Karen Johnson1, David Troyan1, Pavlos Kollias2, Ieng Jo2, Heike Kalesse2, Edward Luke1, Sco@ Giangrande1, Michael Jensen1 1 Brookhaven Na-onal Laboratory, Upton, NY 2 McGill University, Montreal, Canada Current / Upcoming Deployment LocaAons of New Cloud Radars KAZR Ka/W SACR 16
KAZR • Dual-­‐polarizaJon measurements Ka-­‐band Zenith-­‐poinJng Ka-­‐band ARM Zenith-­‐poinAng Cloud Radars (KAZRs) Radar • CollecJng Doppler spectra when at verJcal incidence • Upgraded ARM Fixed Sites: permanent installaJons ARM Mobile FaciliJes: typically 6 – 12 month deployments • Dual-­‐polarized Current deployment of new radar(s) Planned future radar deployment • ConJnuously collecJng Doppler spectra ReflecJvity Best EsJmate KAZR ReflecJvity (long-­‐pulse) Scanning Cloud Radar Products Zenith-­‐poinJng Cloud Radar Products Examples of Zenith-­‐poinAng Cloud Radar Products In Development In Development (IniJal Version Available) KAZR ReflecJvity (short-­‐pulse) * Lowest Cloud base KAZR-­‐ARSCL KAZR Doppler Velocity KAZR observaJons (lel) are corrected, merged and gridded to generate useful products (right column) 1)  Corrected Radar Moments (MPL, ceilometer) 1)  Corrected Radar Product Unfolded Doppler Velocity 2)  KAZR-­‐ARSCL Cloud boundaries (right) are determined by combining observaJons from radar, micropulse lidar (lel) and ceilometer (below). Ceilometer Cloud Base 8
Height (km)
3) Micro-­‐ARSCL 0
Height (km)
The Micro-­‐ARSCL product analyzes Doppler spectra to provide more accurate esJmates of the first three moments: reflecJvity (top right), mean Doppler velocity, and spectral width, plus their uncertainJes. The higher spectral moments, skewness (middle right) and kurtosis are also available. Micro-­‐ARSCL also produces fields of addiJonal informaJon, such as the number of spectral peaks (below right)and lel and right spectral slopes. ReflecJvity 0
5
Height (km)
Micro-­‐ARSCL 5
Skewness -./01"
#"
+"
#)"
##"
%"
3) Horizontal Wind Retrievals 7860"
&"
'"
4560"
,"
("
$"
*"
#*"
•  Applies VAD technique (e.g. Browning and Wexler, 1968) at high elevaJon angles during Hemispheric Sky-­‐RHI scans •  Can be applied in cloud or in insect layers (see example, right) 2.301"
•  Micro-­‐scale product based on Doppler spectra •  Provides Doppler moment shape parameters •  Generates most accurate radar moments, along with their uncertainJes EvaluaJon product available: h@p://www.arm.gov/data/eval/39 4) Combined, SynergisAc Products e.g. Dual-­‐wavelength retrievals Summary 0
5
Number of Sub-­‐peaks 0
14
Based on repeated, specialized Range-­‐Height Indicator (RHI)-­‐type scans: Hemispheric Sky-­‐RHI Along-­‐Wind RHI Cross-­‐Wind RHI !"
Height (km)
Height (km)
Micropulse Lidar Cloud Mask Time of Day(hour UTC)
19
The ARM program conJnuously operates a suite of scanning and zenith-­‐poinJng millimeter wavelength cloud radars at various locaJons around the world. The key to maximizing the research impact of the observaJons is the development of high quality derived products, in combinaJon with other instrument data, which enhance radar observaJon usability. Products are described and examples are given. 10
Significant DetecAon Mask The noise level is determined radial-­‐by radial, using the Hildebrand and Sekhon (1974) technique. An upper value for noise is used to avoid problems in radials containing all or mostly hydrometeor signal. Contact: Karen Johnson, kjohnson@bnl.gov Ka-­‐SACR ReflecJvity 0
10
0
Noise esJmates Too high 160
Too much signal removed -20
X(km)
20
Elevation (deg)
20
Corrected -20
X(km)
20
25
2)  3-­‐D Gridded Product Cloud Boundaries Examples of Scanning Cloud Radar Products •  Feature Mask, Hildebrand and Sekhon (1974) •  Water vapor a@enuaJon correcJon •  Doppler velocity folding corrected •  Insect / Clu@er DetecJon: LDR-­‐based •  Merges radar modes: short-­‐pulse, long-­‐pulse •  Grids best-­‐esJmate moments to 4 s, 30 m •  Cloud boundaries based on combined radar, micropulse lidar and ceilometer observaJons •  Insect / Clu@er DetecJon EvaluaJon product available: h@p://www.arm.gov/data/eval/61 Lowest Cloud base (MPL, ceilometer) •  Significant detecJon mask, Hildebrand and Sekhon(1974) •  Water vapor a@enuaJon correcJon •  Doppler velocity folding corrected •  Fully automated ARM has a 15-­‐year record of cloud radar VAPs, in the form of the first-­‐generaJon AcJve Remote Sensing of 0
24
Time (hours)
CLouds (ARSCL) product. It combines verJcally-­‐poinJng cloud radar, micropulse lidar and ceilometer observaJons to provide high resoluJon gridded fields such as best-­‐esJmate reflecJvity, unfolded Doppler velociJes and hydrometeor boundaries. The ARM program is developing VAPs to enhance the next genera-on of cloud radar observaJons as well. 0
KAZR X/Ka SACR . Received Power (dB)
• OperaJng as Dual-­‐Frequency pairs on a single pedestal (X-­‐Ka or Ka-­‐W) Height (km)
Ka/W Scanning ARM Cloud Radar Height (km)
Ka/W SACR ARM’s new radar suite produces conJnuous long-­‐term high quality data sets. However, the future uJlizaJon of these observaJons and their eventual impact on cloud and precipitaJon research is highly dependent on the development of quality-­‐controlled, readily useable data products, or Value-­‐Added Products (VAPs). Reflectivity Best Estimate
Height (km)
Scanning ARM Cloud Radars (SACRs) ARSCL VAP
Ka-­‐Band A@enuaJon Height (km)
The Department of Energy’s Atmospheric RadiaJon Measurement (ARM) Climate Research Facility is now conJnuously operaJng a suite of new scanning and zenith-­‐
poinJng millimeter wave cloud radars at a number of locaJons around the world: 0
-20
X(km)
20
W-­‐Band A@enuaJon -20
X(km)
Water Vapor ARenuaAon CorrecAon ReflecJviJes are corrected for the effects of gaseous absorpJon. Water vapor a@enuaJon is greatest in humid atmospheres, parJcularly at shorter millimeter wavelengths. At each ARM site, interpolated atmospheric soundings provide temperature, pressure and water vapor density for calculaJng the a@enuaJon correcJon, following Liebe (1985). 20
SACR ReflecJvity 15
Height (km)
Scanning and Zenith-­‐PoinAng ARM Cloud Radar Value-­‐Added Products Ka-­‐SACR, raw W-­‐SACR, raw 0
W.V. Corrected 15
Height (km)
ARM’s New Cloud Radar Suite: 0
-25
X(km)
25
-25
X(km)
25
Horizontal Wind Retrievals SACR Doppler velocity observaJons can be used to retrieve the in-­‐cloud profile of horizontal wind. To the right, velociJes collected using the Hemispheric Sky-­‐RHI scan are mapped to a 3D plane. At each height, up to 12 in-­‐cloud or insect velocity measurements are available. The Velocity-­‐Azimuth Display (VAD) technique is applied to derive horizontal winds. ObservaJons from collocated soundings show good agreement with the VAD-­‐derived wind speeds and direcJons, below. Derived Wind Speed, Insect Layer Cirrus Layer 3D Unfolded Velocity Insect Layer Derived Wind DirecJon, Insect Layer