1. QWG10, Boutin & Hernandez Large scale SSS inter-annual variability in tropical Indian and Pacific Oceans J. Boutin 1, O. Hernandez 1, N. Martin 1, G. Reverdin 1, F. Gaillard 2, S. Morrisset 1 1 CNRS/LOCEAN (CNRS-UPMC-IRD) Paris, France 2 IFREMER/LPO (CNRS-Ifremer-IRD-UBO), Plouzané, France + collaborations with French GLOSCAL SMOS Cal/Val project

2. 2010 : Strong la Niña and negative phase of the Indian Ocean Dipole (IOD) Strong la Niña These events are known to generate large scale SSS anomalies in the tropics (e.g. Gouriou et Delcroix, 2002, Singh et al. 2011, Grunseich et al. 2011) Introduction - IOD QWG10, Boutin & Hernandez

3. DATA: SMOS SSS ESA v5 reprocessing; monthly maps averaged as in (Boutin et al., TGRS, 2012) ARGO + TSG OPTIMAL INTERPOLATED SSS MAPS (ISAS) Monthly maps from In-Situ Analysis System v6 (F. Gaillard, LPO/IFREMER, pers. Comm.) http://wwz.ifremer.fr/lpo/SO-Argo/Products/Global-Ocean-T-S SEA SURFACE AUTONOMOUS DRIFTER SSS Upper S at 45cm depth; Pacific Gyre drifter (Reverdin and Morrisset, LOCEAN) http://www.locean-ipsl.upmc.fr/smos/drifters METHOD: COMPARISON OF SSS ANOMALIES BETWEEN 2010 AND 2011 AS DERIVED BY ISAS AND BY SMOS Data & Methods QWG10, Boutin & Hernandez

4. High contrasted SSS signal between 2010 and 2011 November 2011-2010 July 2011-2010  Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences  In the Pacific Ocean, 2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ QWG10, Boutin & Hernandez

5. High contrasted SSS signal between 2010 and 2011 November 2011-2010 July 2011-2010 Grunseich et al. 2011 SSS Anomaly (1975 – CLM )  Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences  In the Pacific Ocean 2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ  In the Indian Ocean : SSS differences consistent with SSS anomalies reported during negative IOD coupled with Strong La niña event (Grunseich et al. 2011) + + - + + - QWG10, Boutin & Hernandez

6. High contrasted SSS signal between 2010 and 2011 November 2011-2010 July 2011-2010 Grunseich et al. 2011 SSS Anomaly (1975 – CLM )  Good consistence between SMOS 2011-2010 SSS differences and ISAS 2011-2010 SSS differences  2011 - 2010 SSS differences associated with displacement of the ITCZ and SPCZ  In the Indian Ocean : SSS differences consistent with SSS anomalies reported during negative IOD coupled with Strong La niña event (Grunseich et al. 2011) + + - + + - + + - QWG10, Boutin & Hernandez

7. At first order good consistency in SMOS and ISAS 2011-2010 variability but... July 2011-July2010 November 2011-November 2010 Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomalies Why? effect of ARGO/TSG undersampling (=> OI smoothing) and/or a systematic underestimate of SMOS SSS in low SSS/rainy/stratified regions? ISAS SMOS

8. QWG10, Boutin & Hernandez 2011-2010 SSS in N. Trop. Pac. (5°N-15°N) SSS anomaly July 2011-2010 ISAS SMOS Larger westward extent of the fresh SSS as seen by SMOS than by ARGO : stratification or ARGO undersampling? SSS July 2010

9. QWG10, Boutin & Hernandez 2011-2010 SSS in 30°S-0°N region July 2011-July2010 Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomalies ISAS SMOS

10. QWG10, Boutin & Hernandez 2011-2010 SSS in 30°S-0°N region July 2011-July2010 Larger contrasts on SMOS SSS anomalies than on ISAS SSS anomalies July2010 ISAS SMOS Fresh region in 2010 fresher on SMOS than ISAS and very few ARGO in fresh region

11. QWG10, Boutin & Hernandez June 2010 SSS in 30°S-0°N region Surface autonomous drifter (S at 45cm depth) June 2010 Again fresh region in 2010 fresher in SMOS than in ISAS maps DRIFTER SMOS MONTHLY ISAS MONTHLY SSS ISAS SSS SMOS

12. Summary At first order, strong 2011-2010 SSS interannual variability in tropical oceans consistently seen by SMOS and ARGO At first order, in the Pacific Ocean, strong 2011-2010 SSS differences associated with displacement of the ITCZ and SPCZ during La Niña event ; in the Indian Ocean : SSS differences consistent with SSS anomalies already reported during negative IOD coupled with Strong La Niña event 1°x1° 10 days & monthly SMOS SSS (1cm depth) fresher than ARGO & ISAS SSS (~5m depth) in rainy regions : 2 hypothesis: surface stratification and rain effect In situ undersampling and OI smoothing To go further: -apply a similar smoothing to SMOS and ARGO measurements -look at 2012... QWG10, Boutin & Hernandez

14. EXTRA SLIDES QWG10, Boutin & Hernandez

15. SSS SMOS  2011 - 2010 SSS differences associated with displacement of the ITCZ and rainy regions  In the Indian Ocean : Saltier SSS in 2010 associated with smaller rain rate during preceding month  High anomaly around Madagascar not consistent with rainy events. November 2011-2010 October 2011-2010 November 2011-2010 RAIN RATE ? ? Precipitation impact on large scale SSS variability

17. Lower SSS on SMOS than on ISAS when Rain Rate increased