1. SMOS-BEC – Barcelona (Spain) Variable LO freq. Cal. analysis LO at 2min from 23-2-2012 to 23-3-2012 BEC team SMOS Barcelona Expert Centre Pg. Marítim de la Barceloneta 37-49, Barcelona SPAIN E-mail: smos-bec@icm.csic.es URL: www.smos-bec.icm.csic.es

2. 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

3. SMOS-BEC 3/9 SMOS – ARGO 2012 VS 2011 LO = 2 MIN -> 2012 20120223 - 20120324 LO=10 MIN -> 2011 20110223 - 20110324

4. SMOS-BEC 4/9 MEAN/STD/RMS 2011 VS 2012 122 ZONE 126 ZONE 6060 ZONE 122 mean std RMS 23/1-22/2 23/2-22/3 24/3-22/4 LO=2min

5. SMOS-BEC 5/9 SMOS measurements ARGO measurements AREA 122 : 30S – 0N /150W-120W LO = 10 min 20120123 - 20120223 LO = 2 min 20120223 - 20120323 LO = 10 min 20120323 - 20120424

6. SMOS-BEC 6/9 AREA 126 10º S – 10º N LO = 10 min 20120123 - 20120223 LO = 2 min 20120223 - 20120323 LO = 10 min 20120323 - 20120424

7. SMOS-BEC 7/9 AREA 60º S – 60º N LO = 10 min 20120123 - 20120223 LO = 2 min 20120223 - 20120323 LO = 10 min 20120323 - 20120424

8. SMOS-BEC CHI 2 after convergence LO=10min LO=2min

9. SMOS-BEC CHI 2 after convergence LO=10min LO=2min

10. 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

11. 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.

12. SMOS-BEC Analysis LO cal. freq. =2min 23/2-23/3 2011 LO=10min SMOS - ARGO 23/2-23/3 2012 LO=2min SMOS - ARGO Mean (SMOS–ARGO) Std (SMOS–ARGO) LO=2min

13. 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 don’t 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

14. 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) = 1.005 Calibrating every 2 min, 25 snapshots maximum are lost, the L3 error increases by sqrt(500)/sqrt(475) = 1.026 Then the increase of usable snapshots @10 min compared to @2 min implies an error reduction of sqrt(495)/ sqrt(475) = 1.021 This 2.1% reduction on the current SSS accuracy (0.4 psu approx. results in 0.008 psu We showed that calibrating @2 min instead of @10 min implies an error reduction by 0.48 psu in global average

15. SMOS-BEC