1. Overview of SMOS level 2 ocean salinity processing and first results 1 J. Font, J. Boutin, N. Reul, P. Spurgeon, J. Ballabrera, A. Chuprin, C. Gabarró, J. Gourrion, C. Hénocq, S. Lavender, N. Martin, J. Martínez, M. McCulloch, I. Meirold-Mautner, F. Petitcolin, M. Portabella, R. Sabia, M. Talone, J. Tenerelli, A. Turiel, J.L. Vergely, P. Waldteufel, X. Yin, S. Zine, S. Delwart(The SMOS L2 OS Team)ICM-CSIC/SMOS-BEC Barcelona, LOCEAN Paris, IFREMER Brest,ARGANS Plymouth, ACRI-STSophie-Antipolis, ESA-ESTECNoordwijk jfont@icm.csic.es

2. SMOS SSS mission requirements Themultiangularmeasurements of anypointontheEarth’ssurfaceprovidedbythe SMOS interferometricradiometer MIRAS at eachsatelliteoverpass are aimed at: Determining sea surfacesalinitywithanaccuracy of the order of 0.1 practicalsalinityunits, 100 – 200 km spatialresolution and 10 – 30 days temporal resolution Usefulforlargescale oceanographic and climate studies 2 (© P. Carril for ESA)

3. 3 SSS and Tb values Polarisation and viewing geometry provide a higher range of Tb values Sensitivity of Tb to SSS is small especially at low temperatures Retrieving salinity with SMOS is a challenge that requires very good performance of the instrument and a very demanding data processing: new models and algorithms being implemented and now improved

4. SMOS Sea Surface Salinity retrieval 4 Atmosphere Ocean Retrieval from brightness temperature through a convergence loop Comparing model (guessed SSS) with measurements at all incidence angles Sea surface emissivity model (top 1 cm) including roughness effects Other contributions from external sources and atmospheric effects Need for auxiliary data to describe environmental conditions Tb,p = Tb,pflat(θ, SST, SSS) + Tb,p rough (θ, Ф, wind waves, swell, other wave characteristics, foam coverage, foam emissivity, rain)

6. Bias in the comparison of measured and modeled Tb Spatialpatternpersistentalong and in differentorbits Similar usingdifferentoceanemissivitymodels: relatedtoinstrument and imagereconstructionimperfections Removaltechniquesbeingtested: theOcean TargetTransformation (OTT, mean residual biasoverhomogeneousoceanareas) 7 Mainproblems in SSS retrieval (seetalkby M. Talone, Friday)

8. No data averaging

12. 12 Latitudinal SSS gradients S-N SSS anomaly in the Pacific: comparing SMOS and ARGO 0.1 degree bin in latitude, all grids across swath - 1 SMOS half orbit on 11 December 2009 - World Ocean Atlas 2005 SSS climatology - Monthly ISAS analysis of ARGO surface fields in December 2009, Gaillard, LPO, 2010 by J. Boutin & X. Yin, LOCEAN, Paris

13. Combiningseveral SMOS orbits Weekly global salinitymap, July2010: weightedaveraging + discardingflagged data byM. Talone, SMOS-BEC, Barcelona (seetalkby R. Sabia, thisafternoon) 13

14. ComparingdifferentOTTs 14 WARNING: New Flat Target TransformationJuly 2010 SSS anomaly (misfit between retrieved and monthly climatology) by using a single half-orbit OTT SSS anomaly by using a model-independent bias mitigation technique by J. Gourrion, SMOS-BEC, Barcelona (seetalkby M. Talone, Friday)

15. Checkingprocessingoptions 15 Sea surfacesalinityfrom ten days of combinedorbits in theeasternPacificusingonlythe Alias-Free Field-of-View and thethreeroughnessmodels by A. Chuprin, Argans Ltd., Plymouth

16. Analysis of SMOS AF-FOV data a square of 0.25 in instrument coordinate, about 600 * 600 km, (smaller biases and noise) 5 day, SMOS SSS (17-21March, 2010) ascending orbits Only Tb measurements in a square in center of FOV, cleanest Tb by J. Boutin & X. Yin, LOCEAN, Paris 16

18. SMOS and in situ SSS anomalies SMOS - WOA05 SSS of SMOS, WOA05 and ARGO/ISAS averaged into 0.5° bin in latitude Possible reasons for discrepancy SMOS sees 5-day mean SSS at 1 cm depth, while WOA and ISAS SSS are monthly average Is bias removal strategy robust enough? 18

19. Validation of SMOS L2 products Preliminary global validation: March 2010: comparison of SMOS data compositewith 7296 in situ salinityvalues (Argofloats) ~0.5 psu accuracy @ 0.25° resolution by N. Reul, IFREMER, Brest 19 Validationusing L3, J. Ballabrera, SMOS-BEC, Barcelona (seetalkby J. Gourrion thisafternoon)

20. Status of SMOS SSS retrieval Ongoingstudieson: Bias removal techniques Land and RFI contaminationmitigation Forward modelsimprovement Salinitymapsgeneration and validation July 2010: data to Cal/Val teams 20 Seedetailedpresentations: TH3.L02.1 Sabia et al. SMOS measurements preliminary validation against modeled brightness temperatures and external-source salinity data TH3.L02.2 Gourrion et al. Preliminary validation of SMOS products (levels 3 and 4) FR2.L10.5 Talone et al. SMOS brightness temperatures validation: first results after the commissioning phase

22. Define standardized data processing protocols

24. Nov.09: Selected for full-proposal

25. Mar.10: Selected for hearing session