1. Application of AMSR wind speed algorithm for retrieving Windsat vector wind Akira Shibata JAXA AMSR-E meeting, at Huntsville, June 2-3, 2010

2. Backgrounds SeaWinds on Quickscat stopped its operation in November 2009. Then, quality data of wind vector from Windsat became more necessary for analysis of weather forecast. AMSR wind speed algorithm is being applied for retrieving wind vector from Windsat.

3. Parameter Definition AMSR s36 = (36H - (s × (36V – a) + b ) ) / fac parameters a,b, s, fac depend on SST 10H* = AMSR_10H – atmos_effect_10H – calm_ocean_10H 10H* available within no-rainy area because of atmospheric correction using higher frequencies 23/36V Windsat Stokes parameters 18GHz 3 rd /4 th

4. Determination of relative wind direction (AMSR case) - 6H* / s36 plane - 6H* s36 (K) up cross down 7m/s 16m/s wdir positive = downwind wdir available for wind speed greater around 7m/s

5. Conversion of s36 to wind speed (AMSR case) s36 wind speed K m/s After s36 is transformed to cross-wind position

6. Stokes 3 rd /4 th parameter (Windsat case) 45 90 135 225 270 315 10<SST<15 relative wind direction 0/360 upwind

7. Combination of stokes parameters and wdir wdir negativewdir positive

8. Retrieval of wind vector for Windsat Define six lines which form 3 rd /4 th planes, which are variable in SST and 10H* Calculate relative wind direction by position of the nearest line, assisted by knowledge of wdir Temporary, 10H* is used instead of s36 Only retrievable for wind speed larger than around 7m/s, and within no-rainy areas.

9. Windsat 3 rd /4 th plane 5<10H*<79<10H*<11 13<10H*<1517<10H*<19 10<SST<15

10. Comparison of Windsat vector and GANAL (JMA) 12GMT Jan. 1, 2009

11. Comparison of Windsat vector and GANAL (JMA) Jan. 1, 2009

12. Comparison of Windsat vector and GANAL (JMA) Jan. 1, 2009

13. Comparison of Windsat vector and GANAL (JMA)

14. Status Algorithm of retrieving wind direction seems to work well for strong wind, but it needs further works for middle wind. Windsat data problems Due to possible Tb calibration error, s36 has anomalous values, which vary along orbits and monthly. Scan bias errors existing, in particular for s36 Mismatch of spatial locations of s36 and 10H*