1. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI study 9 May 2011 ARGANS & L2OS ESL

2. www.argans.co.uk SMOS L2 Ocean Salinity new 2 step RFI outlier detection algorithm based on reducing outlier threshold if high probability of RFI detected for pol = 0 to 3 /* Stokes 1..4 */ if std(TBmodel[pol] - TBsmos[pol]) > 1.2 * std_theory then rfi_outlier_risk[pol] = TRUE if rfi_outlier_risk[pol] then for each measurement if abs(TBmodel[pol] - TBsmos[pol]) > 3 * rad_noise then Fm_L2_rfi = TRUE where std_theory = √ ((TB_radiometric_noise 2 + TBmodel 2 ) / nMeas) factor of 1.2 is 99% confidence with 100 measurements (1 + 0.18) nsig is reduced from 5 (non-RFI outlier detection threshold) to 3 Outliers & RFI

3. www.argans.co.uk SMOS L2 Ocean Salinity >200 km from land Fg_ctrl_suspect_rfi set if Fm_L2_RFI > 50% L2OS RFI detection (early version of algorithm)

4. www.argans.co.uk SMOS L2 Ocean Salinity >40 km from land Fm_outlier never set because algorithm skipped outlier test if risk of RFI detected L2OS RFI detection (early version of algorithm)

5. www.argans.co.uk SMOS L2 Ocean Salinity no RFI detectionRFI detection Fm_L2_RFI higher % than Fm_outlier (ie more sensitive) L2OS RFI detection (early version of algorithm)

6. www.argans.co.uk SMOS L2 Ocean Salinity no RFI detection RFI detectiondelta Problem: RFI detection works well, but impacts non-RFI retrievals, because measurements discarded if Fm_L2_RFI set even if < 50% L2OS RFI detection (early version of algorithm)

7. www.argans.co.uk SMOS L2 Ocean Salinity Dg_RFI_L2 = count(Fm_L2_rfi) if (Dg_RFI_L2 / Dg_num_meas_L1c) > Tg_num_RFI_max (50%) then Fg_ctrl_suspect_rfi = TRUE if Fg_ctrl_suspect_rfi then if Fm_L2_rfi then Fm_valid = false else /* use ‘normal’ non-RFI outlier test */ if Fm_outlier then Fm_valid = false Outliers & RFI – extended algorithm

8. www.argans.co.uk SMOS L2 Ocean Salinity Fg_ctrl_suspect_rfi set if Fm_L2_RFI > 50% Fm_outlier also set, even if risk of RFI detected Fm_L2_RFI higher % than Fm_outlier (ie more sensitive) L2OS RFI detection (current algorithm)

9. www.argans.co.uk SMOS L2 Ocean Salinity no RFI detection RFI detectiondelta (= RFI – no RFI) Some additional retrievals in Arctic (> 200km from coast) L2OS RFI detection (current algorithm)

10. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection (current algorithm) no RFI detection RFI detectiondelta Additional retrievals in North Pacific & Arctic

11. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection (current algorithm) > 40km from coast > 200km from coast False RFI detection near Antarctic ice

12. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110425T185354_20110425T194756_317_001_1 (unfiltered)

13. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110425T185354_20110425T194756_317_001_1 (filtered: 44329/82665)

14. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_TEST_MIR_OSDAP2_20110425T185354_20110425T194756_500_001_8 (filtered: 48522/82212) L2 RFI outlier test >40km

15. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110502T051050_20110502T060452_317_001_1 (unfiltered)

16. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110502T051050_20110502T060452_317_001_1 (filtered: 17957/62361)

17. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_TEST_MIR_OSDAP2_20110502T051050_20110502T060452_500_001_8 (filtered: 21683/61963) L2 RFI outlier test >40km

18. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110430T085851_20110430T095250_317_001_1 (unfiltered)

19. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_TEST_MIR_OSDAP2_20110430T085851_20110430T095250_500_001_8 Fg_ctrl_suspect_RFI

20. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_OPER_MIR_OSDAP2_20110430T085851_20110430T095250_317_001_1 (filtered: 17899/53953)

21. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 SM_TEST_MIR_OSDAP2_20110430T085851_20110430T095250_500_001_8 (filtered: 21506/53520) L2 RFI outlier test >40km

22. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_SCSF1C_20110313T055704_20110313T065103_346_001_1

23. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_OSDAP2_20110413T141055_20110413T150454_317_001_1

24. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_OSDAP2_20110413T155057_20110413T164459_317_001_1

25. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_OSDAP2_20110413T164100_20110413T173501_317_001_1

26. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_SCSF1C_ 20110413T041028_20110413T050427_346_001_1

27. www.argans.co.uk SMOS L2 Ocean Salinity L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_OSDAP2_20110313T200742_20110313T210141_317_001_1

28. www.argans.co.uk SMOS L2 Ocean Salinity unfiltered filtered Fm_L2_RFI Fg_ctrl_suspect_rfi L2OS RFI detection comparing 0317 & v500 317500 no RFI detection 500 with RFI detection SM_OPER_MIR_OSDAP2_20110313T123721_20110313T133122_317_001_1

29. www.argans.co.uk SMOS L2 Ocean Salinity Outliers & RFI Conclusions – new L2 RFI algorithm detects RFI – once detected, RFI measurement selection enables &/or improves retrieved salinity – L1 coast contamination causes false RFI positives – RFI thresholds need tuning with new L1 – L2OS configuration can turn RFI detection/mitigation off if required

30. www.argans.co.uk SMOS L2 Ocean Salinity Decision: RFI distance-to-coast >40km>200km SM_TEST_MIR_OSDAP2_20110313T005649_20110313T015043_318_001_8

31. www.argans.co.uk SMOS L2 Ocean Salinity Decision: RFI distance-to-coast >40km>200km Set coast limit >40km & find good values for RFI_std, RFI_nsig &Tg_num_RFI_max with new L1PP