Simulated response of South Atlantic Subtropical Mode Water to air-sea processes

The subtropical mode water is formed as a deeper mix layer, during the wintertime, due the processes that occur in the air-sea interface. In the South Atlantic, we can find three formation cores of the subtropical mode water between 30◦S and 40◦S: in the western and eastern part of the basin, and north of the Subtropical Front. Each one of these three types presents typical mean thickness and horizontal distribution patterns, mainly because of the particular dynamic and thermodynamic characteristics of each part of the South Atlantic related to these three formations.In view of assessment the effects of the wind, surface heat flux, precipitation and evaporation on the South Atlantic Subtropical Mode Water volume daily variation, numerical experiments were designed using the National Center for Atmospheric Research (NCAR) with the Community Earth System Model version 1.0.5 configuration (CESM1.0.5). Therefore, we began by observing the effects of idealized wind, heat fluxes and freshwater fluxes anomalies over one year of model simulation. The anomalies patterns were all distributed on the ocean surface equally for all the cases, using different intensity and values for each case. By comparing to a control run, we were able to observe that each type of subtropical mode water formation responded differently. This feature can be seen in the magnitude and sign of the anomaly of the mix layer thickness and mode water volume. These different responses of each type of mode water lead us to the conclusion that there are three distinct formation processes, involving the dominance of different air-sea processes, that can lead us to advance our understanding of the ocean response to air-sea interface interaction.