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L2OS status summary

L2OS status summary. The SMOS L2 OS Team. What does not allow SMOS by now to reach the mission requirements for OS retrieval? Background issue: low sensitivity Tb/SSS MIRAS calibration still to be improved

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L2OS status summary

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  1. L2OS status summary The SMOS L2 OS Team

  2. What does not allow SMOS by now to reach the mission requirements for OS retrieval? Background issue: low sensitivity Tb/SSS MIRAS calibration still to be improved Image reconstruction imperfections (side lobes impact, Sun removal, land/sea transitions, ...) RFI in some specific ocean areas Geophysical modelling deficiencies (galactic noise, TEC variability, roughness correction, ...) SMOS OS retrieval problems 2

  3. What are the main issues we have to face before applying the salinity inversion scheme? Spatial biases in reconstructed image Variability at different time scales not due to OS variability (calibration drifts, geophysical conditions) L1 related problems dominate the quality of retrieved salinity SMOS OS retrieval problems 3

  4. Mitigation by L2OS as L1 post-processing: Constant OTT built from one ascending orbit in S. Pacific (until L2OS v3.17) Constant OTT built from 10 orbits in S. Pacific (L2OS v5.00) OTT from 10 orbits, different ascending/ descending, and updated monthly for DPGS and every 2 weeks for reprocessing (L2OS v5.50) SMOS OS retrieval problems 4

  5. Recent improvements in L2 processor (v5.50): Time-varying and asc/desc differentiated OTT to mitigate residual biases and drifts Better outliers sorting and RFI management Improved roughness correction models Main remaining problems related to: Suneffects in OTT Galacticnoisescatteringmodel Impact of TEC variabilitywithinsnapshot 2012 OS retrieval performance 5

  6. Reprocessing performance SSS1 v316 unfiltered SSS1 v550 unfiltered SSS1 v550 filtered http://www.argans.co.uk/smos/pages/products.php 6

  7. Reprocessing performance SSS1 v316 unfiltered SSS1 v550 unfiltered SSS1 v550 filtered Larger impact on descending orbits due to double OTT http://www.argans.co.uk/smos/pages/products.php 7

  8. Reprocessing performance 10-days/1o averaged SSS 3 -12 August 2011 Zonal average SMOS-Argo Old processors +0.2 - 0.2 New processors L1 v3.46 v5.04 L2OS v3.17 v5.50 by J. Martínez, ICM/SMOS-BEC 8

  9. Temporal evolution of mean OTT bias by P. Spurgeon, ARGANS FTT#1 FTT#3 FTT#2 0K Asc. -4K Temporal oscillations of meanbiases: 1 K, period ~4months Desc. May 2010 May 2011 Last change of Flat Target Transformation (FTT) 9

  10. OTTs: drift in median delta TB by P. Spurgeon, ARGANS Max. 0.5 K Seasonal variation of Asc – Desc biases: amplitude ~1K 10

  11. OTTs May 2010-Dec 2011 2K 2K STD of ascending OTTs STD of descending OTTs all year no April-August all year only April-August Clear disturbance due to the presence of sun alias in the FOV: • Ascending orbits: April to August • Descending orbits: Whole year except April to August X Y 0.2 0.2 by X. Yin, LOCEAN 11

  12. SMOS OS validation through L3 Monthly 1º maps: regional comparisontoArgo SMOS ascending orbits ±300 km 3-12 m/s wind Bias - 0.04 0.02 - 0.07 - 0.15 STD0.25 0.38 0.48 0.31 SSS September 2011 SMOS (up), Argo (bottom) by J. Boutin et al., LOCEAN 12

  13. Global SMOS OS validation • SMOS OS L3 BEC map 1ox1o • Optimal Interpolation using WOA2009 as background • 15-24 Jan. 2012 • Argo SSS interpolated at -7.5 m SMOS - Argo 1299 points Bias = -0.11 RMS = 0.42 by J. Martínez, ICM/SMOS-BEC 13

  14. SSS SMOS through the years WOA 2009 SSS anomalies (WOA 2009) SSS difference 2010 2011 - 2010 2010 2011 2011 2010: El niño 2011: La niña by S. Guimbard, ICM/SMOS-BEC

  15. Analysis of reprocessed L1 and L2 data Analysis of switched land/ocean LO calibration test Identifying OTT issues and exploring solutions New galactic noise scattering model Use of polarimetric information for TEC estimation Improving RFI / filtering options Tuning roughness correction models SMOS-Aquarius comparisons SMOS L2OS recent work 15

  16. Variable LO frequency calibration test analysis LO at 2 min from 23-Feb-2012 to 23-March-2012 C. Gabarró and 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

  17. ANALYZED ZONES Tropics and mid-latitudes 60S:60N Equatorial Ocean 10S:10N Zone 126 Southern Pacific 30S:0N – 150W:120W Zone 122

  18. SMOS – ARGO 2012 VS 2011 LO = 2 MIN -> 2012 20120223 - 20120324 Bias = 0.3 STD = 0.5 LO=10 MIN -> 2011 20110223 - 20110324 Bias = 0.1 STD = 0.7

  19. MEAN/STD/RMS 2011 VS 2012 122 Equatorial S. Pacific mean std std mean RMS RMS 60 S – 60 N 24/3-22/4 23/1-22/2 mean std 23/2-22/3 LO=2min RMS

  20. AREA 122: 30ºS – 0º/150ºW-120ºW Feb 23 – Mar 23 LO = 2 min 2012 Jan 23 – Feb 23 SMOS measurements ARGO measurements Mar 23 – Apr 23 2011 2012

  21. AREA 126: 10º S – 10º N Jan 23 – Feb 23 Feb 23 – Mar 23 LO = 2 min 2012 Mar 23 – Apr 23 2011 2012

  22. AREA 60º S – 60º N Jan 23 – Feb 23 Feb 23 – Mar 23 LO = 2 min 2012 Mar 23 – Apr 23 2011 2012

  23. Effects on the coastal areas • Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq. No evident impact on coastal areas When using a variable LO cal. frequency 23

  24. Effects on the coastal areas • Analysis of the impact of the change of calibration frequency near the coast. Comparison before and after setting the variable LO cal. freq. No evident impact on coastal areas When using a variable LO cal. frequency Difference due to a large wind event

  25. Conclusions • From previous decimation studies: • LO calibrated @10 min degrades TB wrt @2 min by 0.47 K (STD global average) • SSS (filtered by good retrieval flag) degrades by 0.48 psu global (0.20 psu in optimal conditions, S. Pacific) • The increase of usable snapshots @10 min compared to @2 min implies an error reduction of 0.008 psu

  26. Conclusions • From variable land/ocean calibration test: • The anticipated 10 / 2 min differences have not been observed in the March 2012 test • No evidence has been found of any impact of increasing the LO calibration frequency over ocean • Any possible impact appears to be hidden by stronger effects on OS quality • The L2OS team has not reached a consensus on the advantages / disadvantages of this calibration mode • No recommendation is submitted to QWG concerning its operational implementation

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