1. High Quality Wind Retrievals for Hurricanes Using the SeaWinds Scatterometer W. Linwood Jones and Ian Adams Central Florida Remote Sensing Lab Univ. of Central FL

2. Presentation Outline Hurricane Wind Vector Retrieval Issues CFRSL Hurricane Retrieval Algorithm QRad Rain Rate Algorithm Isabel and Fabian Results Conclusion

3. Issues with L2B Wind Vector Retrieval for Extreme Wind Events Wind retrievals not tuned for high wind speeds  Geophysical Model Function developed for wind speeds < 20 m/s CFRSL Approach  Tropical Cyclone GMF tuned for retrieving high wind speeds  Blended UMASS aircraft scat measurements and NSCAT GMF

4. Issues with L2B Wind Vector Retrieval for Extreme Wind Events Egg spatial resolution @ 25 km sampling is too coarse CFRSL Approach  Uses gridded “slice sigma-o” @ 12.5 Km sampling

5. 25 km resolution using “eggs” 50 km 25 km Longitude Latitude

6. Range gated “slices” from “egg” 6 km 30 km 12.5 km 25 km

7. Issues with L2B Wind Vector Retrieval for Extreme Wind Events Rain has negative effects on wind measurements  Rain attenuation lowers retrieved wind speeds  Volume scattering increases retrieved wind speeds and alters directional signatures  Rain “splash” increases retrieved wind speeds and changes anisotropic ocean surface features  MUDDH performance in hurricanes is poor

8. Issues with L2B Wind Vector Retrieval for Extreme Wind Events Rain has negative effects on wind measurements CFRSL Approach  Simultaneous rain measurement using QRad  Rain attenuation and volume backscatter correction provided  Rain splash effect included in GMF  Rain Quality Flags Provided

9. CFRSL Hurricane Retrieval Algorithm “Slice” sigma-0’s for improved spatial resolution - 12.5 km Sigma-0 minimum eye location Wind speed retrieved from individual sigma-0 (assumed spiral wind directions) Rain inferred using QRad rain rate algorithm Sigma-0 corrections from atmospheric transmissivity and rain volume backscatter Flag pixels that correspond to high rain attenuation

10. QRad Algorithm Block Diagram Bin Slice Sig-0 Spiral Wind Direction Atmos. Atten and Backscatter Correction L2A Tb’s Hurricane Wind Speed QScat L1B sig-0 Locate Center QRad Rain Rate Retrieve Wind Speed Hurricane Wind Retrieval

11. Hurricane Eye Location Based upon Average of “4-flavor” Sigma-0’s 12.5 km sampling Longitude Latitude

12. QRad/SRad Rain Algorithm Look at noise channel of scatterometer  Subtract echo channel  Calibrate radiometric temperature vs. TMI Train brightness temperature/rain rate relationship via TMI Coincident with scatterometer measurement

13. QRad Integ. Rain Rate Product Improved CFRSL rain retrieval algorithm provides earth-gridded 50 km data product Instantaneous integrated rain rates > 2.4 km*mm/hr Resampled to 12.5 km wind vector grid

14. QRad – TRMM 2A12 Instantaneous Rain Rate QRad TMI Longitude Latitude Land

15. QRad – TRMM 3B42RT HQ Instantaneous Collocated Low Rain event QRad TMI

16. QRad – TRMM 3B42RT HQ Instantaneous Collocated Moderate Rain event QRadTMI

17. QRad – TRMM 3B42RT HQ Instantaneous Collocated High Rain Event QRadTMI

18. QRad (CFRSL) & TMI Integrated Rain Rates for Simultaneous Events TMI Integ. Rain Rate, km*mm/hr CFRSL Integ. Rain Rate, km*mm/hr

19. AMSR vs. SRad Path Attenuation, Horizontal Polarization 10 2 AMSR Attenuation SRad Attenuation

20. 2003 Hurricane Results

21. HRD Wind Field, Time Interpolated CFRSL Wind Retrieval QRad Rain Rate (mm/hr) QuikSCAT Rev. 22055, Sept 13, 2003 22:04 Z (m/sec) SSMI Rain Rate

22. HRD Wind Field, Time Interpolated (m/sec) SeaWinds Rev. 03927, Sept 15, 2003 15:40 Z SRad Rain Rate (mm/hr) CFRSL Wind Retrieval SSMI Rain Rate

23. CFRSL Wind Retrieval SRad Rain Rate (mm/hr) HRD Wind Field, Time Interpolated (m/sec) QuikSCAT Rev. 22084, Sept 15, 2003 22:52 Z SSMI Rain Rate

24. HRD Wind Field 01:30 Z SeaWinds Rev. 03934, Sept 16, 2003 02:52 Z CFRSL Wind Retrieval SRad Rain Rate (mm/hr) (m/sec) SSMI Rain Rate

25. HRD Modeled Wind Speed (m/s) CFRSL Wind Speed (m/s) HRD Modeled Wind Speed (m/s) JPL Wind Speed (m/s) SeaWinds Rev. 03934, Sept 16, 2003 02:52 Z JPL Wind FieldCFRSL Wind Retrieval

26. QuikSCAT vs. H* Wind Analysis

27. SeaWinds vs. HRD Model

28. CFRSL Algorithm Composite Wind Speeds

29. Conclusion Ready to test current algorithm in operational environment  Acceptable estimates of high rain rates inside storm conditions  Reasonable wind speed retrievals up to 40 - 45 m/s Work must be done to improve model function and rain backscatter and attenuation estimates  Will utilize UMass IWRAP and SFMR data set  Have simultaneous AMSR and SRad for the 2003 hurricane season

30. Backup Slides

31. Error contribution of spiral direction