Baroclinic rossby waves and the South Atlantic meridional overturning circulation

Abstract

The South Atlantic Meridional Overturning Circulation (SAMOC) is an ocean circulation pattern composed by geostrophic and ageostrophic currents and its subsequent transport of heat and freshwater. It mainly impacts ocean stratification since density regulates the vertical distribution of water masses and its horizontal gradients are responsible for the deep geostrophic circulation. Rossby waves play a key role in large-scale circulation, controlling the western boundary currents in a baroclinic model, and consequently the subtropical gyre. In that way, variations of this waves mechanic energy would be in principle related to the SAMOC transport variation. Previous studies identified propagating signals in the meridional transport at 34.5oS, which may be associated both to Rossby waves and mesoscale eddies. Since first mode baroclinic Rossby waves at mid-latitudes are highly influenced by stratification, we propose to investigate in which depth or density bands these waves are more clearly identified using temperature and salinity profiles available from in-situ data and sea surface height data measured by satellite altimetry. Therefore, we intend to assess the role played by stratification in the amplitude of Rossby waves, comparing data from the three ocean basins at 11oS, 24.5oS e 34.5oS and if there is any significant contribution of the energy transported by groups of these waves to the western boundary current at the South Atlantic Ocean. (AU)