SMOS-BEC Barcelona (Spain) Variable LO freq. Cal. analysis LO at 2min from to BEC team SMOS Barcelona Expert Centre Pg. Martim de la Barceloneta 37-49, Barcelona SPAIN URL: SMOS-BEC Barcelona (Spain) 2/9 ZONES Tropics and mid-latitudes 60S:60N Tropics and mid-latitudes 60S:60N Equatorial Ocean 10S:10N Zone 126 Equatorial Ocean 10S:10N Zone 126 Southern Pacific 30S:0N 150W:120W Zone 122 Southern Pacific 30S:0N 150W:120W Zone 122 SMOS-BEC 3/9 SMOS ARGO 2012 VS 2011 LO = 2 MIN -> LO=10 MIN -> SMOS-BEC 4/9 MEAN/STD/RMS 2011 VS ZONE 126 ZONE 6060 ZONE 122 mean std RMS 23/1-22/2 23/2-22/3 24/3-22/4 LO=2min SMOS-BEC 5/9 SMOS measurements ARGO measurements AREA 122 : 30S 0N /150W-120W LO = 10 min LO = 2 min LO = 10 min SMOS-BEC 6/9 AREA S 10 N LO = 10 min LO = 2 min LO = 10 min SMOS-BEC 7/9 AREA 60 S 60 N LO = 10 min LO = 2 min LO = 10 min SMOS-BEC CHI 2 after convergence LO=10min LO=2min SMOS-BEC CHI 2 after convergence LO=10min LO=2min SMOS-BEC Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq. 10 No evident impact on coastal areas When using a variable LO cal. frequency Effects on the coastal areas SMOS-BEC Difference due to a large wind event Effects on the coastal areas No evident impact on coastal areas When using a variable LO cal. frequency Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq. SMOS-BEC Analysis LO cal. freq. =2min 23/2-23/ LO=10min SMOS - ARGO 23/2-23/ LO=2min SMOS - ARGO Mean (SMOSARGO) Std (SMOSARGO) LO=2min SMOS-BEC 13 Conclusions - From QWG-5 Conclusions from decimated study: The present LO calibration frequency has a clear impact on TB (larger in V-pol) and SSS. TB differences between LO-10min and LO-2min have a global STD of 0.47 K (1.1K in N. Atlantic, 0.21 K in Pacific) Differences in SSS (filtered by good retrieval flag): global STD 0.48 psu (0.94 psu in N. Atlantic, 0.20 psu in Pacific) Accuracy requirement for L2 SSS is 1.2 psu. We dont know yet the actual retrieval error, but the low calibration freq can represent in average 0.5 psu of additional error!! SMOS SSS requirements will likely never be met with LO being calibrated at 10 min intervals SMOS-BEC During 10 minutes 500 SMOS snapshots are acquired. In every calibration event 5 snapshots are lost. When calibrating LO every 10 min, the error in building an L3 map by averaging L2 products (wrt no calibration) increases by sqrt (500)/sqrt(495) = Calibrating every 2 min, 25 snapshots maximum are lost, the L3 error increases by sqrt(500)/sqrt(475) = Then the increase of usable min compared min implies an error reduction of sqrt(495)/ sqrt(475) = This 2.1% reduction on the current SSS accuracy (0.4 psu approx. results in psu We showed that min instead min implies an error reduction by 0.48 psu in global average SMOS-BEC
