La salinité de surface, thème fédérateur d’OLVAC

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1 La salinité de surface, thème fédérateur d’OLVAC
Etudes s’appuyant sur le SO SSS, les satellites SMOS/Aquarius, la modélisation Thématique présente sur tous les chantiers géographiques OLVAC, à différentes échelles spatio-temporelles, centrale dans plusieurs thèses tendances climatiques long terme impact des fleuves dynamique IOD dynamique saisonnière circulation australe climat régional dynamique ENSO

2 ENSO-related SSS changes
Eastern Pacific El Niño Central Pacific El Niño SST SSS Different SSS anomalies near the eastern edge of WP fresh pool and under SPCZ (Singh, Delcroix & Cravatte, 2011) 2 2

3 Associated equatorial mechanisms
Mixed layer salt budget in forced model: advection term not extending eastward of dateline in CP Niño no eastern precipitation forcing in CP Niño strong subsurface forcing in EP Niño Eastern Pacific El Niño Central Pacific El Niño pss/yr (Hasson, Delcroix & Dussin, 2013)

4 East Pacific Fresh Pool seasonal cycle
M O SMOS can monitor the fresh pool Wind/Rain JAS Surface Currents JFM Panama gap wind Upwelling Summer rain => SSS minimum, fresh pool building Westward advection of fresh pool by SEC Ekman pumping => upwelling in Panama Bight, fresh pool destruction (Alory, Maes, Delcroix, Reul & Illig, 2012)

5 Impact of river discharges in Bay of Bengal
Ganges + Brahmaputra SSS with seasonal runoff + interannual runoff anomaly resulting SST anomaly 1998: strong discharge Model simulations with or without interannual runoff anomaly (Durand, Papa, Rahman & Bala, 2011)

6 Indian Ocean Dipole SSS signature
SMOS SSS 12/2011 – 12/2010 IOD+ IOD- Largest year-to-year signal in SMOS data, related to IOD-/IOD+ succession Validation SMOS SSS in situ SSS WOA SSS Both data and model agree on dominant role of advection (Durand, Alory, Reul & Dussin, en cours)

7 Tropical Atlantic SSS budget from mixed layer model
Climatological model validation Seasonal balance in selected regions Dominant processes for mean state (Da-Allada, Alory, Dupenhoat, Kestenare, Durand & Hounkonnou, 2013)

8 Interannual variations in SURVOSTRAL SubAntarctic Zone
Correlation Maria Is TSG 2012 2000 1993 SAZ : SSS – Seasonal mean (DJFM) SAZ AZ Southward penetration of Tasman Sea inflow (Morrow & Kestenare, en cours)

9 Global SSS trends ( ) Obs Mean SSS Observed trends reflect the « wet gets wetter, dry gets drier » Clausius-Clapeyron effect Local effect + mean currents Models capture the increasing Pacific-Atlantic contrast despite biases (double ITCZ) Obs SSS trend CMIP3 models SSS trend (Terray, Corre, Cravatte, Delcroix, Reverdin & Ribes, 2012)

10 Conclusion Bon week-end!
Poursuivre les observations sur le long-terme (in situ + satellite) Bonne synergie entre SO et recherche associée (CNAP) Transversalité: cycle de l’eau, couplage océan-atmosphère... Bon week-end!