1. SMOS-BEC – Barcelona (Spain) LO calibration frequency impact Part II C. Gabarró, J. Martínez, V. González, A. Turiel & 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 QWG-7 ESRIN, 31 January – 1 February 2012 LO CAL FREQ ANALYSIS INDEX 1)BRIEF SUMMARY OF QWG-4 (March-2011) & QWG- 5 (June) RESULTS & CONCLUSIONS : - ICM STUDY - UPC STUDY 2)NEW ANALYSIS WITH DECIMATED DATA FROM MARCH 2010 (processors v500) 2)ANALYSIS OF NOVEMBER/ DECEMBER 2011 DATA (using 2 weeks of LO=2min) 2

3. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 ICM QWG-4 STUDY 3 20100325T040821 descending TBH_10min-TBH_2minTBV_10min-TBV_2min Decimation Study (10min, 6min and 2min) 57 orbits from 24th – 25th March 2010 TB_10min-TB_2min

4. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 4 SSS LO 10min -2min SSS LO 6min -2min ICM QWG-4 STUDY SSS LO 10min - 2min

5. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 6min-2min 10min-2min Spatial structures appear both cross-track and along-track The structures are still present after averaging data with decimated calibration. (Tx+Ty)/2 averaging 0 to 40º incidence angles. UPC LO ANALYSIS 5

6. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 UPC LO ANALYSIS 10min-2min 6min-2min The LO-phase error induces structure in xi-eta Average of 126 snapshots of TBn-TB2 6

7. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 CONCLUSIONS FROM QWG-4 & 5 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. LO phase drift produces non-random visibilities errors -> TB spatial structures in xi-eta. Relatively small phase error (low STD) may have impact on the image due to this systematic behaviour. Spatial structures are expected in SSS retrievals due to imperfect LO phase error cancellation. Differences in SSS global STD 0.48 psu. 7

8. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 LO Cal Freq Analysis in QWG-7 2) DATA SET: DECIMATION STUDY 24th-26th March 2010 (81 semi-orbits) with MIRAS at LO=2 min Repeated the decimitation with the newest versions of processors: L1PP5.00 (no land-sea contamination bug) L2PP5.00 8

9. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Different impact across track : Spatial structures, as observed in UPC study. SSS 10 min- SSS 2min X-Swath (Km) SSS 10 min- SSS 2min Averaging One half-orbit from Pacific (similar with many) 2) DECIMATION MARCH 2010 9

10. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 3 days, 81 semi-orbits Strong filtering (optimal conditions) World except N. Atlantic & Med. Different OTTs for 2, 6, 10 min. Large Reduction of STD in TB Reduction of tails 2) DECIMATION MARCH 2010 TB 10 min- TB 2min TB 6 min- TB 2min 10 Comparing calibration at 10 min vs. 6 min 0.550.15

11. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 SSS 10min – SSS 2min Latitudinal average Lat=[45S, 30N] Bias = 0.05 psu Std = 0.11 psu Lat=[45S, 30N] Bias = 0.05 psu Std = 0.11 psu SSS L3 map 10 min – SSS L3 map 2 min -> 3 days, 0.5 o binned Filtered by: X-Swath < 400 km Poor_geo & poor_ret 2) DECIMATION MARCH 2010 11

12. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 2) DECIMATION MARCH 2010 Significant reduction of bias & Std SSS by going to 6min, reduction of tails Accuracy req. SSS maps 0.1 psu. -> low cal. freq implies additional non negligible error! SSS maps -> done - averaging 81 s-orb - 4H9 - Filtered by poor_geophysical poor_retrieval SSS maps -> done - averaging 81 s-orb - 4H9 - Filtered by poor_geophysical poor_retrieval SSS 10 min- SSS 2min SSS 6 min- SSS 2min WORLDLAT=[45S, 30N] 12 0.28 0.07 0.16 0.11 Comparing 10 and 6 min.

13. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 3) DATA FROM NOVEMBER – DECEMBER 2011: 3 periods of 10 days have been selected (from DPGS) 20th – 29th November : LO=10 min 6th – 15th December : LO=2 min 20th - 29th December : LO=10 min Maps of 10 days at 4H9 have been constructed. 13

14. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Mean AVERAGE (SMOSminus ARGO) Periods of 10 days -> one every 3 days Mean AVERAGE (SMOSminus ARGO) Periods of 10 days -> one every 3 days high variation over time 5-19 Dec LO =2min LO effect between different periods of time is masked 01-10 July 2011 31 Dec, 2011 10 Jan 2012 Mixed LO data 2min & 10 min 3) DATA FROM NOV. – DEC. 2011 L1PP500 L2PP500 L2PP550 14

15. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 SSS Nov 21 to 30 (LO = 10min)- SSS Dec 6 to 15 (LO = 2min) Latitudinal average 3) DATA FROM NOV. – DEC. 2011 15 Lat=[45S, 30N] Bias = 0.25 psu -> higher than decimated Lat=[45S, 30N] Bias = 0.25 psu -> higher than decimated

16. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 (SSS 10min – SSS 2min )_AB = Δ_impact_LO_AB + Δ_SSSvariability_AB + Δ_other_AB (SSS 10min – SSS 2min )_AB = Δ_impact_LO_AB + Δ_SSSvariability_AB + Δ_other_AB 20-29 Nov LO =10min 6-15 Dec LO =2min 20-29 Dec LO =10min Period APeriod B Period C Estimated with ARGO measurements Estimated with ARGO measurements Includes TEC, Sun, galaxy, instrument … Hard to estimate; we have used a linear interpolation from AC period Includes TEC, Sun, galaxy, instrument … Hard to estimate; we have used a linear interpolation from AC period TO BE ESTIMATED 3) DATA FROM NOV. – DEC. 2011 To compare data from different periods it is necessary to consider all the factors that contribute to the differences in SSS. 16

17. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 4H9 L3 binned map averaged to 1x1 degree 4H9 L3 binned map averaged to 1x1 degree low noise: candidate to detect LO contribution Lat: 0N-30S Bias = -0.21 Lon: 180W-90W STD = 0.34 low noise: candidate to detect LO contribution Lat: 0N-30S Bias = -0.21 Lon: 180W-90W STD = 0.34 highly noisy (SSS 10min – SSS 2min )_AB 3) DATA FROM NOV. – DEC. 2011 Δ_impact_LO_AB = (SSS 10min – SSS 2min )_AB - Δ_SSSvariability_AB - Δ_other_AB 17

18. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Δ_SSSvariability_AB Optimal interpolation 1x1 degree Optimal interpolation 1x1 degree Differences between OI maps of ARGO measurements Differences between OI maps of ARGO measurements 3) DATA FROM NOV. – DEC. 2011 Δ_impact_LO_AB = (SSS 10min – SSS 2min )_AB - Δ_SSSvariability_AB - Δ_other_AB 18

19. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Δ_other_AB high noise: LO effect will be masked high noise: LO effect will be masked low noise: changes in other factors low enough to allow assessing LO contribution Latitude: 0N-30S Longitude: 180W-90W low noise: changes in other factors low enough to allow assessing LO contribution Latitude: 0N-30S Longitude: 180W-90W 3) DATA FROM NOV. – DEC. 2011 Δ_impact_LO_AB = (SSS 10min – SSS 2min )_AB - Δ_SSSvariability_AB - Δ_other_AB 19

20. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Δ_impact_LO_AB = -0.03 bias, 0.3 std in the most favorable case Δ_impact_LO_AB 3) DATA FROM NOV. – DEC. 2011 Δ_impact_LO_AB = (SSS 10min – SSS 2min )_AB - Δ_SSSvariability_AB - Δ_other_AB 20 LO cal. freq. seems to impact on land contamination

21. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 Δ_impact_LO_AB in optimal situation Lat=[30S, 0N] Lon=[180W, 90W] Mean: -0.0320 psu Median: -0.0318 psu Std dev.: 0.2940 psu Δ_impact_LO_AB in optimal situation Lat=[30S, 0N] Lon=[180W, 90W] Mean: -0.0320 psu Median: -0.0318 psu Std dev.: 0.2940 psu 3) DATA FROM NOV. – DEC. 2011 Δ_impact_LO_AB 21 ∆_SSSvariability mean = 0.0183 median = 0.0206 std = 0.1126 ∆_other mean = -0.2579 median = -0.2559 std = 0.1831

22. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 CONCLUSIONS (I) In previous QWG it was shown that LO impact is not negligible nor at TB neither at SSS level. TB spatial structures in xi-eta and across track are observed  Study on decimated data (3 days, March 2010) using v500: - TB 10min – 2min: mean= 0.07 K & std=0.54 K - SSS L3 0.5 o binned maps 10min – 2min: bias = 0.08 psu & Std = 0.28 psu  Study of two different periods (Nov-Dec 2011) - Instrumental factors are much larger than LO contribution (thus hard to estimate). However, our analysis points to a significant LO impact on SSS maps (under optimal conditions: box in S Pacific) bias = -0.03 psu & std = 0.29 psu 22

23. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 CONCLUSIONS (II) Evidence is limited as the data for the study are limited. However, now as before, the issue seems serious enough to be taken into account. Incremental studies on incremental samples of data will probably lead to more or less the same conclusions. Processing improvements (CW and so on) are unlikely to change this situation. Definitively: with 10 min LO calibration we will never meet the mission requirements over ocean 23

24. SMOS QWG-7 ESRIN, 31 January – 1 February 2012 24 In summary: 10 min kills SMOS salinity requirements Processing options will not help Time to turn on Guillermo’s proposal