SMOS Quality Working Group Meeting #2 Frascati (Rome), September 13 th -14 th,2010 SMOS-BEC Team

2 / Ntot Outline METHODOLOGY TESTS 1. RETRIEVAL MODE Dual from Full vs. Stokes from Full 2. BIAS MITIGATION No correction vs. External Bias Temperature Calibration vs. OTT 3. MODELS Model 2 vs. Model 3(16) 4. SSS SELECTION All overpasses vs. Ascending vs. Descending 5. TB SELECTION EAF vs. AF 6. NEW FTR July vs. August CONCLUSIONS (+ or -)

3 / Ntot Methodology All the results presented are at Level 3 (10-day 2-degree product). Retrievals have been performed using SMOS-OS Level2 Processor. Level 2 data have been filtered according to: Fg_ctrl_reach_maxiter1,2,3 : Maximum number of iteration reached before convergence. Fg_ctrl_marq1,2,3 : Iterative loop ends because Marquardt increment is greater than lambdaMax (100). Statistical characterization is done considering only points more than 200 km from the coast Fg_sc_land_sea_coast1 = 1 & Fg_sc_land_sea_coast2 = 0

4 / Ntot Methodology L2 L3 averaging has been performed according to: The L3 accuracy is also introduced to someway estimate the quality of the measurement

5 / Ntot Tests 1.RETRIEVAL MODE 10 days of retrieval from July, 10 th to 19 th ISEA4H9 ISEA4H8 to reduce the computational resources needed Model 2 in the mode “Stokes from Full-Pol” has been used OTT has been applied in accordance to the official DPGS product L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

6 / Ntot Tests – Dual vs. Stokes’ I L3 maps - Dual Amazon plume Cold waters

7 / Ntot Tests – Dual vs. Stokes’ I L3 maps - Stokes’ I Amazon plume Cold waters

8 / Ntot Tests – Dual vs. Stokes’ I L3 maps

9 / Ntot Tests – Dual vs. Stokes’ I L3 maps - Accuracy 2.5 psu

10 / Ntot Tests – Dual vs. Stokes’ I L3 statistics - Dual rms rms

11 / Ntot Tests – Dual vs. Stokes’ I L3 statistics – Stokes’ I rms % rms % % +8%

12 / Ntot Tests 2.BIAS MITIGATION 10 days of retrieval from July, 10 th to 19 th ISEA4H9 ISEA4H8 to reduce the computational resources needed Model 2 in the mode “Dual from Full-Pol” has been used No correction, external brightness temperature calibration [*], and OTT have been applied L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

13 / Ntot Tests – Bias mitigation External Brightness Temperature Calibration Constant within the snapshot (xi, eta) but varying in time Ocean Target Transformation Constant in time but varying within the same snapshot

14 / Ntot Tests – Bias mitigation L3 maps – No bias mitigation

15 / Ntot Tests – Bias mitigation L3 maps – External Brightness Temperature Calibration

16 / Ntot Tests – Bias mitigation L3 maps – External Brightness Temperature Calibration MEAN BIAS SUBTRACTED Less intense land-sea transition effect

17 / Ntot Tests – Bias mitigation L3 maps – Ocean Target Transformation

18 / Ntot Tests – Bias mitigation L3 maps - Accuracy 2.5 psu

19 / Ntot Tests – Bias mitigation L3 statistics – no bias mitigation rms rms

20 / Ntot Tests – Bias mitigation L3 statistics – External Brightness Temperature Calibration rms rms % -20% -52% -37%

21 / Ntot Tests – Bias mitigation L3 statistics – Ocean Target Transformation rms rms % -73% -68% -78%

22 / Ntot Tests 3.MODELS 10 days of retrieval from July, 10 th to 19 th ISEA4H9 ISEA4H8 to reduce the computational resources needed OTT has been applied as for the official DPGS product Model 2 and Model 3(16) are compared L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

23 / Ntot Tests – Model 2 vs. Model 3(16) L3 maps – Model 2

24 / Ntot Tests – Model 2 vs. Model 3(16) L3 maps – Model 3(16)

25 / Ntot Tests – Model 2 vs. Model 3(16) L3 maps

26 / Ntot Tests – Model 2 vs. Model 3(16) SST L3 maps

27 / Ntot Tests – Model 2 vs. Model 3(16) WS L3 maps FROM ASCAT

28 / Ntot Tests – Model 2 vs. Model 3(16) Scatterplot

29 / Ntot Tests – Model 2 vs. Model 3(16) L3 maps - Accuracy 2.5 psu

30 / Ntot Tests – Model 2 vs. Model 3(16) L3 statistics – Model 2 rms rms

31 / Ntot Tests – Model 2 vs. Model 3(16) L3 statistics – Model 3(16) rms rms % +21% +27%

32 / Ntot Tests 4.SSS SELECTION 10 days of retrieval from July, 10 th to 19 th ISEA4H9 ISEA4H8 to reduce the computational resources needed OTT has been applied as for the official DPGS product L3 averaging has been performed using ALL the overpasses, only the ASCENDING ones, and only the DESCENDING ones L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

33 / Ntot Tests – All vs. Ascending vs. Descending L3 maps - All

34 / Ntot Tests – All vs. Ascending vs. Descending L3 maps - Ascending Fresher when ice/land enters in the FOV Saltier when it exits

35 / Ntot Tests – All vs. Ascending vs. Descending L3 maps - Descending Generally saltier Fresher when ice/land enters in the FOV Saltier when it exits

36 / Ntot Tests – All vs. Ascending vs. Descending L3 maps – comparisons with Ext TB cal

Tests – All vs. Ascending vs. Descending land-sea contamination a previous study

38 / Ntot Tests – All vs. Ascending vs. Descending L3 statistics - All rms rms ALL PASSES

39 / Ntot Tests – All vs. Ascending vs. Descending L3 statistics - Ascending rms rms % = +52% +9%

40 / Ntot Tests – All vs. Ascending vs. Descending L3 statistics - Descending rms rms % +22% +27% +46%

41 / Ntot Tests 5.TB SELECTION 5 days of retrieval from July, 10 th to 14 th ISEA4H9 has been used Model 2 in the mode “Dual from Full-Pol” is analized OTT has been applied as for the official DPGS product TB with a have been filtered out to almost reproduce the AF-FOV L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

42 / Ntot Tests – EAF vs. AF AF-FOV approx.

43 / Ntot Tests – EAF vs. AF L3 maps - EAF

44 / Ntot Tests – EAF vs. AF L3 maps - AF

45 / Ntot Tests – EAF vs. AF L3 maps – AF minus EAF Ascending positive Descending negative

46 / Ntot Tests – EAF vs. AF L3 statistics - EAF rms rms

47 / Ntot Tests – EAF vs. AF L3 statistics – AF rms rms % +11% +5% +13%

48 / Ntot Tests 6.NEW FTR 10 days of retrieval from July, 10 th to 19 th and August, 20 th to 29 th are compared as produced by the DPGS: ISEA4H9 has been used Model 2 in the mode “Dual from Full-Pol” is analyzed OTT has been applied L3 retrieved SSS is compared to NOAA WOA05 climatology and ARGO averaged data

49 / Ntot Tests – July vs. August L3 maps - July

50 / Ntot Tests – July vs. August L3 maps - August Generally fresher

51 / Ntot Tests – July vs. August August minus July

52 / Ntot Tests – July vs. August L3 statistics - July rms rms

53 / Ntot Tests – July vs. August L3 statistics – August rms rms % -8% +6% -17%

Conclusions (+ or -) 1. Dual from Full vs. Stokes from Full 4-14 % increment in SSS misfit rms using Stokes’ I 2. No correction vs. External Bias Temperature Calibration vs. OTT Ext TB cal. partially diminishes the SSS misfit rms, OTT has a very strong improvement effect. Ext TB cal partially corrects for the land-sea transition effect and seems to work better in the North Atl. waters (?) The combined use of both techniques can be envisaged… 3. Model 2 vs. Model 3(16) Model 3 is still in definition, conf. 16 (from WISE) has been used, performing relatively close to Model 2. difference between models are strongly related to SST. 4. All overpasses vs. Ascending vs. Descending Waters appear fresher when land/ice enters in the FOV and saltier when it exits when using only ascending or descending passes, the effect is compensated using both. Descending passes give generally saltier SSS.

Conclusions (+ or -) Ext TB calibration gives more homogeneous results…again the combined use can be envisaged… 5. EAF vs. AF Using only AF FOV a positive bias has been found in the ascending passes, negative in the descending, w.r.t the case of using EAF FOV. Change in statistics is small. 6. July vs. August August 10-day SSS misfit is in average psu fresher than July’s SSS misfit. Anyway statistics are very similar and no clear improvement can be observed.