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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. High Quality Wind Retrievals for Hurricanes Using the SeaWinds Scatterometer. Presentation Outline. Hurricane Wind Vector Retrieval Issues CFRSL Hurricane Retrieval Algorithm QRad Rain Rate Algorithm

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High Quality Wind Retrievals for Hurricanes Using the SeaWinds Scatterometer

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

  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 Retrievalfor 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 Retrievalfor 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 Latitude Longitude

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

  7. Issues with L2B Wind Vector Retrievalfor 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 Retrievalfor 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. QScat L1B sig-0 Bin Slice Sig-0 QRad Rain Rate L2A Tb’s Locate Center Atmos. Atten and Backscatter Correction Spiral Wind Direction Hurricane Wind Retrieval Retrieve Wind Speed Hurricane Wind Speed QRad Algorithm Block Diagram

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

  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 Latitude Longitude Land QRad TMI

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

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

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

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

  19. AMSR vs. SRad Path Attenuation, Horizontal Polarization SRad Attenuation AMSR Attenuation 102

  20. 2003 Hurricane Results

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

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

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

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

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

  26. QuikSCAT vs. H* Wind Analysis

  27. SeaWinds vs. HRD Model

  28. CFRSL AlgorithmComposite 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

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