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Outline OPC overview Impact Warnings and Features Hurricane Force Winds

The Operational Impact of QuikSCAT Winds at the NOAA Ocean Prediction Center Joe Sienkiewicz – NOAA Ocean Prediction Center Joan Von Ahn – STG/NESDIS ORA. Outline OPC overview Impact Warnings and Features Hurricane Force Winds SST impacts on near surface winds Summary and Recommendations.

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Outline OPC overview Impact Warnings and Features Hurricane Force Winds

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  1. The Operational Impact of QuikSCAT Winds at the NOAA Ocean Prediction Center Joe Sienkiewicz – NOAA Ocean Prediction CenterJoan Von Ahn – STG/NESDIS ORA • Outline • OPC overview • Impact • Warnings and Features • Hurricane Force Winds • SST impacts on near surface winds • Summary and Recommendations

  2. OPC Responsibility Wind Warning Categories GALE – 34-47 knots Force 8/9 STORM – 48-63 knots Force 10/11 HURRICANE FORCE - 64 knots and greater Force 12

  3. Wind speed (knots)

  4. Warning Impact Interpreted forecaster comments Forecaster input only Additional training Timelines added Forecaster query Percent Change in Short-Term Warning Decisions by OPC

  5. Changes topositionofsurface features Changes to Warning Category Changes to Wind Speed Changes to Wind Field Changes to position of surface features Changes to Warning Category Changes to Wind Field Changes to Wind Speed Winter 2004 (Feb 15 to Mar 15)When QuikSCAT was available, changes were made to:68 % of the events in the Atlantic 50% of the events in the PacificEvent- Lows, Highs and Wind areas (speed and aerial extent) Atlantic Pacific

  6. (a) (b) Hurricane Force Winds QuikSCAT able to distinguish between STORM and HURRICANE FORCE winds

  7. APL China – Oct 1998 OOCL America M/V Explorer

  8. Hurricane Force Cyclones…What have we learned? • Winter events – October through March (April) • Most frequent – Atlantic (January); Pacific (December) • Minimum SLP (avg. 965 to 970 hPa) • Minimum SLP - larger range in Atlantic • Explosive deepeners • Western portion of basins (most frequent); preferred tracks • Short lived (less than 24 hours) (avg. lifecycle 5 days) • Shallow warm core seclusion • Wind max S to SW of low • Most difficult to forecast at day 4 forecast time over North Pacific • Less than 10 % forecast 4 days in advance!! Number of HF Cyclones observed

  9. X L X L Pacific Atlantic Composite of maximum winds (knots) HF FORCE STORM GALE Pacific (11 cyclones) Atlantic (5 cyclones) Composite of QuikSCAT winds for 11 North Pacific and 5 North Atlantic HF storms. This plot shows the distribution of maximum winds as observed by QuikSCAT for all cyclones in the composite. HF winds are Red, Storm -Yellow and Gale –Green.

  10. SST Impacts on Near Surface Winds

  11. 12.5 km QuikSCAT 3-day GOES SST Composite 25 km QuikSCAT Wind speed difference (GFS 10m-QuikSCAT)

  12. GFS 10 WInds 12.5 km QuikSCAT Bias corrected 10m Winds Wind speed difference (knots) (GFS 10m-QuikSCAT)

  13. Eta 10m GFS 10m GFS 9950 Sigma 30 day avg. diff 11/05/04 Model Winds - QSCAT Very Unstable PBL 975-skin < -4

  14. Eta 10m GFS 10m GFS 1st Sigma Eta 10m GFS 10m GFS 1st Sigma 30 day avg. diff Model Winds - QSCAT Very Stable PBL 975-skin > 4

  15. SST impacts on Wind Field Due to QuikSCAT OPC forecasters are more conscious of underlying SST on near surface winds (always knew an impact but forecasters can now see it) Forecaster tools model soundings stability indices mix of 1st sigma and 10m winds wind speed difference fields

  16. QuikSCAT Rain QuandryJanuary 4, 2005

  17. 12.5 km QuikSCAT SSM/I Wind Speeds 25 km QuikSCAT SSM/I Rain Rate

  18. 12.5 km QuikSCAT QuikSCAT Ambiguities 25 km QuikSCAT SSM/I Rain Rate There are times when our forecasters do not know what to believe!

  19. SummaryImpact - Significant • Cultural change to ocean analysis and forecasting within OPC • 10 % Wind Warnings determined by QuikSCAT • Assessment of features more accurate • Ability to assess initial numerical model conditions • Can differentiate between significant and extreme winds Storm versus Hurricane Force • Significance of PBL stability on near surface winds • QuikSCAT winds have changed the way we do business • Precip Quandry • At times just do not know impact on wind retrievals

  20. Recommendations(for future instruments) • Large swath width • Independent rain measurement • Ability to quantify impact of rain • Large retrievable wind range (0 to Hurricane Force) • 12.5 km resolution or better • Reduced land mask (less than 30 km) • Minimum 4 looks per day per ocean (from operational platforms) • Data access near-real time (1 to 1.5 hour delivery after acquisition…no more) • Available in forecaster workstations in comprehensive form

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