Ocean Salinity Stratification in Models and Observations

Jack Reeves Eyre and Xubin Zeng

Department of Hydrology and Atmospheric Sciences

The University of Arizona 

Salinity plays an important part in ocean vertical mixing processes, and therefore affects exchange of heat, momentum and moisture between the atmosphere and ocean. In turn, the atmosphere affects (surface) salinity through precipitation, which decreases salinity, and evaporation, which increases salinity. Some regions of the ocean, for example rainy regions in the tropics, have increasing salinity with depth in the upper ocean, which inhibits vertical mixing and may affect the propagation of internal waves that can play a role in climate variability.

The portrayal of such features, termed barrier layers, in coupled earth system models has not been widely studied, and here we present results from several models and observations. The questions we attempt to address are: Do models represent barrier layers in agreement with observations? Are biases in salinity related to biases in precipitation and/or sea surface temperature? Are there connections between salinity biases and SST and precipitation variability - for example El Nino Southern Oscillation or the Madden-Julian Oscillation?