Retrieving Ocean Surface Wind Speeds from the Nonspinning QuikSCAT Scatterometer
Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist,...
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Transcript of Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist,...
![Page 1: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/1.jpg)
Experimental Uses of QuikSCAT at TPC and Future Requirements
Jack Beven
Hurricane Specialist, Tropical Prediction Center
Chris Hennon
Visiting Scientist, UCAR, Tropical Prediction Center
![Page 2: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/2.jpg)
Outline
• Operational Applications and Examples of QuikSCAT
• Applied Research– Auto center detection– Dealing with rain
• Future– WindSat– Operational Requirements and Desires
![Page 3: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/3.jpg)
Does a circulation center exist?Is this center fix accurate?
Is 50 kt an accurateMSW measurement?
Is this a valid representationof the 34 kt. wind radii?
Isabel (45 kt from Dvorak)
How timely isthe QSCT Pass?
![Page 4: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/4.jpg)
Operational Examples
![Page 5: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/5.jpg)
A good center location
![Page 6: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/6.jpg)
A bad example - QuikSCAT can fail to detect circulation centers,even in tropical storms or hurricanes
Erika (45 kt from aircraft)
![Page 7: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/7.jpg)
Fausto (2003) – distance betweenpositions = 56 mi
When a center is found, it is frequently in the wrong place
NRCS analysis may provide a more accurate center
![Page 8: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/8.jpg)
QuikSCAT Research at TPC
![Page 9: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/9.jpg)
Auto Center Detection• Motivation
– For TDs and TSs, QuikSCAT solution contains a discernable fix about 35% of the time
– The ambiguity field may contain a circulation center not shown in the solution field
– In general, operational time constraints do not allow a manual ambiguity analysis
– An automated ambiguity analysis procedure will identify any possible circulations and assign a confidence level to each
• Confidence based on directional probabilities embedded in data
![Page 10: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/10.jpg)
Draw 4 x 4 degree (or user specified size) box around chosen location
![Page 11: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/11.jpg)
![Page 12: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/12.jpg)
Rain Contamination
• Rain severely limits QuikSCAT usefullness for:– Wind Radii estimation (esp. 50 and 64 kt.)– Circulation center detection– Maximum wind estimation
• Can we ‘correct’ the retrieved wind speeds based on the rain rate?
![Page 13: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/13.jpg)
Operational Rain Correction?
• Need QuikSCAT retrieved wind speed, hi-res rain rate, and ‘true’ wind speed to develop an algorithm– Accurate rain rate generally not available (no radiometer on board)– Good surface wind speed analysis for TCs difficult if not
impossible in most situations
• Can MUDH rain probability serve as a proxy for rain rate?– MUDH considers brightness temperature and normalized beam
difference – two parameters that should be correlated with rain rate
– If so, than a correction algorithm may be developed
• Two TRMM/QuikSCAT coincident passes analyzed
![Page 14: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/14.jpg)
Fabian 2 Sep. 2003TRMM 0244 QSCAT 0159
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60
Rain Rate (mm/hr)
MU
DH
Pro
b.
![Page 15: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/15.jpg)
Can WindSat Provide Usuable TC Retrievals?
![Page 16: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/16.jpg)
Rain Not Likely Rain Likely
Fabian (2003)- Verification against QSCAT
![Page 17: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/17.jpg)
Verification against surface wind analysis (Fabian 3 Sep. 2003 2147 UTC)
H*Wind Wind Speed
WindSat – H*Wind
WindSat Rain Rate (experimental)
Highest differencesexactly match heavy rain areas
Generally good agreementaround storm periphery
Very Large (> 10 m/s)differences over muchof the storm
Figures courtesy of Ian Adams (UCF)
![Page 18: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/18.jpg)
Isabel (2003)
Windsat September 14
QuikScat September 15
WindSat figure courtesy of Zorana Jelenak (NESDIS)
![Page 19: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/19.jpg)
Summary
• QuikSCAT has been useful in many cases for operational application– Center detection, location, wind radii
• Rain impacts and lack of rain information severly limits further use of QuikSCAT winds
• Preliminary TC WindSat looks not encouraging– Development continues
![Page 20: Experimental Uses of QuikSCAT at TPC and Future Requirements Jack Beven Hurricane Specialist, Tropical Prediction Center Chris Hennon Visiting Scientist,](https://reader034.fdocuments.us/reader034/viewer/2022051618/56649d3f5503460f94a19042/html5/thumbnails/20.jpg)
Requirements for Future Missions
• Wind measuring instrument and rain detection instrument on the same satellite – CMIS instrument on NPOESS will fulfill this
• Less ambiguity in the measurements• More coverage!• New techniques (physical, model function)
– Limit rain effects
– Developed specifically for tropical cyclones