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Impacts and Challenges of Integrating QuikSCAT into TPC Operations

Impacts and Challenges of Integrating QuikSCAT into TPC Operations. Christopher Hennon UCAR Visiting Scientist Tropical Prediction Center March 17, 2004. National Ocean Partnership Program (NOPP) Project. Goals Enhance operational utility of surface wind vector data (wvd) at TPC

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Impacts and Challenges of Integrating QuikSCAT into TPC Operations

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  1. Impacts and Challenges of Integrating QuikSCAT into TPC Operations Christopher Hennon UCAR Visiting Scientist Tropical Prediction Center March 17, 2004

  2. National Ocean Partnership Program (NOPP) Project • Goals • Enhance operational utility of surface wind vector data (wvd) at TPC • Quantify impacts of high resolution wvd at TPC • Investigate new scatterometer products as they become available • SeaWinds on Midori-II (dead) • WindSat (passive polarimetric radiometry) • Collaborative effort between six agencies • NESDIS, OPC, TPC, BYU, NRL, OCENS

  3. Outline • SeaWinds on QuikSCAT • Description / operation • End product • QuikSCAT Use at TPC • Tropical Cyclones • Tropical Marine Forecasts and Analyses • Current QuikSCAT research at TPC • Impact Study • Tropical Cyclone center fixing • Challenges and Future Work • Concluding Remarks

  4. SeaWinds on QuikSCAT • Active Ku Band (13.7 GHz) scatterometer • Able to retrieve high resolution (25 or 12.5 km) 10-meter wind speed and direction • Cross swath width of 1800 km • 90% global coverage daily • Accurate within 2 m/s for wind speeds of 2-20 m/s (~4 - 40 kt) • Assuming no rain

  5. QuikSCAT Operation 803km 46 deg 53 deg 900km

  6. Some QuikSCAT Applications at TPC • Locations of weak tropical cyclones • Outer wind field structure of mature tropical cyclones • Locations of tropical waves • Analyzing pressure fields • Wind/wave forecasting • Offshore waters forecast • Verification of ship and buoy observations • Verification with model analyses and SSM/I winds • Diagnoses of high-wind events • Gulf of Tehuantepec

  7. SSMI MSW = 25 kt. (TD) MSLP = 1008 mb 11.2N 23.0W ( BT, 0000 Z 9/9)

  8. T.S. force wind radii MSW = 140 kt. MSLP = 932 mb

  9. 40+ kt wind event confirmed by QuikSCAT. Confident warnings can be made

  10. QuikSCAT Improves TPC Analysis and Forecasting • Improvements in finding tropical waves, mesoscale wind events, and creating accurate pressure analyses over oceans • Outer band wind structure in tropical cyclones • Accurate fixes of weaker tropical cyclones (sometimes) • Used in conjunction with other microwave imagery

  11. Current Research and Strategies • Quantify impact of operational QuikSCAT data on tropical marine forecasting • Goal: Identify uses, strengths, and shortcomings of operational QuikSCAT wind retrievals

  12. Methodology • Forecasters asked to complete log sheet after each forecast cycle • One log sheet for each forecast desk • 15-Nov – 15-Dec (2003)

  13. QuikSCAT Log Sheet – Pacific Desk Forecaster Name: _________________________________ Date (mm/dd) _______ / _______ For Synoptic Time __________ UTC 1) Did you use quikSCAT wind vectors for any of your products (circle one)? YES NO 2) If you answered ‘YES’ to #1, for which products did you apply quikSCAT information? 3) If you answered ‘NO’ to #1, why didn’t you use quikSCAT wind vectors in your products (please circle)? a. No data available b. Data available but not timely c. No relevant information from quikSCAT data d. Rain contamination / edge of swath problems e. Other (please comment) _____________________________________________ _____________________________________________ 4) If you answered ‘YES’ to #1, how did the quikSCAT data change your analysis/forecast from what it would have been without the data (circle all that apply)? a. Forecasted/Analyzed higher wind speeds for the region of _________ N _________ W b. Forecasted/Analyzed lower wind speeds for the region of _________ N _________ W c. Changed the pressure and/or wave forecast(s) for (circle) front / tropical wave / ridge d. Resulted in the issuance or upgrade of a wind warning for _______ N _______ W e. Resulted in a downgrade of a wind warning for _________ N _________ W f. QuikSCAT data did not change my analysis/forecast g. Other (please specify in box below) Comments – Please note any relevant comments here

  14. Results • Main Findings: • QuikSCAT data used during the forecast cycle about 75% of the time • When QuikSCAT data changed the wind analysis/forecast, the new winds were usually higher in velocity (65%, lower 35%) • The main reason QuikSCAT was not used during the forecast cycle was lack of timeliness (37%) or no data available (32%)

  15. Selected Forecaster Comments “Used to place features like fronts & troughs, tighten isobars near hi wind speeds” “Verify position of 1010 mb low in EPAC near 11N 126W” “Only small area of EPAC available - not much help” [rain contamination] “Prevented finding location of Low in SW Caribbean - vectors implied no circulation. Had to consult sat imagery and surface obs.” “ Adj wnds to 40kt in Gulf of Tehuantepec gale area based on 00Z qsct pass of 40 kt.” “Confirmed AVN fcst for 06Z and SSMI imagery. Qsct in good agreement” “Higher winds 15N, 120W & Papagayo, lower wnds 20N, 108W. Missing data hurt!” “Windward Passage - confirmed ship obs of 25-30 kt.” “Would be nice to have current qsct passes for 00Z run”

  16. Current Research and Strategies • QuikSCAT tropical cyclone fix study • Goals • Determine under what conditions (strength of surface wind, presence/strength of rain, etc.) an accurate center fix from QuikSCAT can be realized. • Explore analyses of directional ambiguities as a method of improving center fixing capabilities

  17. Challenges • Tropical cyclones contain large areas of heavy rain • Wind vector retrievals frequently ineffective, both in speed and direction • In high wind variance events (Gulf of Tehuantepec), rain flagging algorithm fails • Forecasters need to trained on what to use and when • Timely coverage sometimes not available • Scanning geometry results in bad retrievals near edge of swath and near nadir

  18. MSW = 20 kt. (TD) MSLP = 1009 mb 13.8N 28.7W ( BT, 0600 Z)

  19. Future Work • Explore better techniques for using QuikSCAT wind velocities in convective areas • Evaluate higher resolution data (12.5 km), available soon to forecasters • Ambiguity analyses • Explore accuracy of QuikSCAT vs. new surface wind products (WindSat)

  20. Concluding Remarks • Loss of Midori-II satellite eliminates enhanced scatterometer coverage for at least the next two years • QuikSCAT will continue to provide valuable near surface wind data for all coastal areas through at least 2006 • Very accurate in most instances!!

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