Sea surface salinity from a simplified ocean mixed layer model using global altimeter data
Sylvain MICHEL(1) , Bertrand CHAPRON(1) , Jean TOURNADRE(1) , and Nicolas REUL(1)
A vertically integrated 2D model of the ocean mixed layer is used to estimate the anomalies of Sea Surface Salinity (SSS) caused by atmospheric heat fluxes, evaporation-precipitation budget, wind friction and geostrophic circulation. The input parameters are the Sea Surface Temperature and air/sea fluxes derived from ECMWF meteorological model and the geostrophic currents from SSALTO-DUACS altimetry analysis.
The model is first tested with a high-frequency climatological forcing dataset, in terms of variability and space distribution of SSS response. It is shown that variations in wind-induced transport is the first cause of salinity variability, but fresh water flux and geostrophic transport can dominate locally.
Then the analysis is performed over several recent years, using an optimal combination of space-borne observations and model outputs. The results are validated using in situ measurements from buoy arrays in the tropical Pacific (TAO) and Atlantic (PIRATA), then using gridded fields from ARGO drifters over the North-Atlantic (Coriolis analysis). Finally, the interest of this method and its real-time application is examined in view of the future SMOS and Aquarius satellites, which will both be dedicated to SSS retrieval.