Influence of precipitation and evaporation on the sea surface salinity

The salinity at the oceans' surface is changed due to the exchange of freshwater with the atmosphere in form of precipitation and evaporation. The contributions of other processes like oceanic advection and mixing and river run-off is the key subject of the SMOS mission.

Mean sea surface salinity in February and March between 2010 and 2014, measured by SMOS, filtered and gridded to 1x1 degree.

As a case study, the region in the southeastern tropical Pacific is investigated: An annual band of precipitation along 5° S in the months March to May is correlated with low salinity water in the zonal band. The fresh water budget of this region shows that it's not only the precipitation being responsible for the low salinity, but that also the advection of low salinity water from the north contributes to a similar chnage in salinity. The advected fresh water originates in the eastern Pacific fresh pool (EPFP), being situated just north of the equator and being fed by the precipitating moisture from the Atlantic ocean.

Correlation between precipitation (GPCP) und sea surface salinity anomalies in SMOS between 2010 and 2014 (colormap). Red contours show the mean precipitation rate in cm per month. The investigated area is hatched..

This study can be found in Sena Martins und Stammer (2015) .