Volumetric Characterization of the South Atlantic Subtropical Mode Water Types

Time series (2002-2018) of a global monthly objectively analyzed fields of temperature and salinity were used to investigate the South Atlantic subtropical mode water (SASTMW). It is characterized as homogeneous layers in the temperature range of 13 to 16 degrees C and with low potential vorticity. Three different types of SASTMW were distinguished allowing us to evaluate their temporal volumetric variation. Each type has its distinct spatial and temporal distribution patterns and consequently dissimilar volumetric variation. This variability is seen in the volume anomaly and turnover time of each type. To examine these differences we compared two rates: the water formation in a given temperature range due to heat flux and the mode water formation. The first (13.1 +/- 2.4 Sv) is higher than the second (10.2 +/- 2.0 Sv), showing that although heat flux is essential for the formation of SASTMW, there are other factors that influence each type differently.