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Systematic SMOS Error There: Roughness ? SST ?

From N. Reul talk at EGU 2011. El-Nina SSS anomalies detected by SMOS in August. Systematic SMOS Error There: Roughness ? SST ?. From Boutin, Lorant et al. at PM20: Example of wind speed difference. WSssmi : 1.8 m/s WSecmwf : 6.85 m/s WSsmos: 4.23m/s SSSsmos-SSSargo : 1.578 psu

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Systematic SMOS Error There: Roughness ? SST ?

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  1. From N. Reul talk at EGU 2011 El-Nina SSS anomalies detected by SMOS in August Systematic SMOS Error There: Roughness ? SST ?

  2. From Boutin, Lorant et al. at PM20:Example of wind speed difference WSssmi : 1.8 m/s WSecmwf : 6.85 m/s WSsmos: 4.23m/s SSSsmos-SSSargo : 1.578 psu (Ecart temporel : -0.306 h)

  3. From Xiaobin analysis (August, ascending orbits, S. Pacific, new model) <300km >300km ECMWF-SMOS WS Equator SSS anomaly corresponds to a SMOS retrieved wind speed lower than ECMWF Edge of the swath : Origin of systematic bias on the not understood (not seen north of the equator.. Galactic noise???)

  4. SSS1(<300km)-ARGO/ISAS SSS1(<300km)-WOA05 -Monthly averaged August 2010- SMOS WS <300km ECMWF WS diff >300km WS diff <300km SMOS retrieval not able to correct for WS at the swath edge (not enough incidence angle) SSMI WS: much lower than ECMWF WS

  5. In situ TAO wind speed at 2S 110W:On 6 August, ECMWF ~5m/s TAO <3m/s

  6. New analysis over 1 orbit on 6 August: (without averaging over 0.1° latitudinal bin) Monthly average over 0.5° latitudinal bin

  7. SSS retrieved using EAFFOV and only +/-250km centered swath New analysis: error 2m/s New analysis: error 5m/s SSS bias reduced with increasing error on WS

  8. Wind speed retrieved using EAFFOV and only +/-250km centered swath New analysis: error 2m/s New analysis: error 5m/s More correction on WS when WS error increased

  9. SSS retrieved with 5m/s error on WS (only +/-250km centered swath) Use of AFFOV(square in Xi, Eta of 0.25°) Use of EAFFOV Better correction on SSS when using AFFOV

  10. Wind speed retrieved with 5m/s error on WS (only +/-250km centered swath) Use of AFFOV (square in Xi, Eta of 0.25°) Use of EAFFOV Larger correction on WS when using AFFOV

  11. SSS anomaly (only centered swath) Use of AFFOV(square in Xi, Eta of 0.25°) (5m/s error on WS) Use of EAFFOV (2m/s error on WS) Less bias on SSS when putting an error of 5m/s on WS but larger noise!

  12. Summary • SMOS SSS anomaly in equatorial Pacific seems to be due to a roughness effect not enough corrected • SMOS retrieved wind speed lower than ECMWF but not enough low • If the error on ECMWF WS is increased, SMOS retrieved WS lower and bias on SSS removed (when using AFFOV), but larger noise on retrieved SSS! • Not clear whether it is a problem in ECMWF wind speed or in roughness effect on microwave radiometer (SSMI wind speed very close to SMOS WS but TAO?)

  13. ECMWF versus TAO wind speed (Jean Bidot, ECMWF) 2S-110W No systematic bias of ECMWF analysis although monthly SSMI wind speed lower than SMOS-ECMWF wind speed East of 140W, S. Eq.

  14. ECMWF versus TAO wind speed (Jean Bidot, ECMWF) 0S-110W Real bias or Pb of TAO?

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