SMOS STORM KO meeting 30/01/2012 ESRIN Ocean Surface Remote Sensing at High Winds with SMOS.
Systematic SMOS Error There: Roughness ? SST ?
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Transcript of Systematic SMOS Error There: Roughness ? SST ?
SystematicSMOS ErrorThere:Roughness ?SST ?
From N. Reul talk at EGU 2011
From Boutin, Lorant et al. at PM20:Example of wind speed difference
WSssmi : 1.8 m/sWSecmwf : 6.85 m/sWSsmos: 4.23m/sSSSsmos-SSSargo : 1.578 psu(Ecart temporel : -0.306 h)
From Xiaobin analysis (August, ascending orbits, S. Pacific, new model)
<300km >300km ECMWF-SMOS WS
Edge of the swath : Origin of systematic bias on the not understood (not seen north of the equator.. Galactic noise???)
Equator SSS anomaly corresponds to a SMOS retrieved wind speed lower than ECMWF
SSS1(<300km)-WOA05 SSS1(<300km)-ARGO/ISAS
WS diff <300km WS diff >300km
-Monthly averaged August 2010-
SSMI WS: much lower than ECMWF WS
SMOS WS <300km ECMWF
SMOS retrieval not able to correct for WS at the swath edge (not enough incidence angle)
In situ TAO wind speed at 2S 110W:On 6 August, ECMWF ~5m/s TAO <3m/s
New analysis over 1 orbit on 6 August:(without averaging over 0.1° latitudinal bin)
Monthly average over 0.5° latitudinal bin
New analysis: error 2m/s New analysis: error 5m/s
SSS retrieved using EAFFOV and only +/-250km centered swath
SSS bias reduced with increasing error on WS
New analysis: error 2m/s New analysis: error 5m/s
Wind speed retrieved using EAFFOV and only +/-250km centered swath
More correction on WS when WS error increased
Use of EAFFOV Use of AFFOV(square in Xi, Eta of 0.25°)
SSS retrieved with 5m/s error on WS (only +/-250km centered swath)
Better correction on SSS when using AFFOV
Use of EAFFOV Use of AFFOV (square in Xi, Eta of 0.25°)
Wind speed retrieved with 5m/s error on WS (only +/-250km centered swath)
Larger correction on WS when using AFFOV
Use of AFFOV(square in Xi, Eta of 0.25°)
(5m/s error on WS)
SSS anomaly (only centered swath)
Use of EAFFOV (2m/s error on WS)
Less bias on SSS when putting an error of 5m/s on WS but larger noise!
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?)
ECMWF versus TAO wind speed (Jean Bidot, ECMWF)
2S-110W
East of 140W, S. Eq.
No systematic bias of ECMWF analysis although monthly SSMI wind speed lower than SMOS-ECMWF wind speed
ECMWF versus TAO wind speed (Jean Bidot, ECMWF)0S-110W
Real bias or Pb of TAO?