Analysis of the variability of sea surface salinity and temperature extremes in the North Atlantic ocean.

Sea Surface Salinity (SSS) plays an important role in the global water cycle, which appears to be intensifying due to climate change and influences the vertical distribution of heat in the ocean because of its influence on water density. The role of SSS in the onset and offset of Marine Heat Waves (MHWs) and cold spells, or the changes induced on SSS by these extreme events has not been adequately addressed.

 

In this work we analyse the variations of SSS before, during and after MHWs and cold spells in the North Atlantic Ocean, in order to address the role of SSS and the atmospheric conditions in the evolution of MHW events. We also assess the occurrence of compound extreme temperature /salinity events and determine the regions and conditions under which these occur. Both high and low SSS anomalies are detected during MHWs, which indicates different oceanic and atmospheric processes are at play during each event. Large differences are observed between satellite SSS estimates and reanalyses, especially in coastal regions. Therefore, the first step when assessing SSS extreme high and low values consists on an intercomparison of the different products available in order to establish a reference climatology.

 

Compound events can cause more damage to the ecosystem than individual events. It is therefore necessary to establish the relation between extreme temperature and salinity compound events, and establish their spatio-temporal patterns in different regions, in order to understand the origin of these events and which are the drivers that lead to their formation.