How does the baroclinic vertical modes relate to Rossby waves observed by altimetric satellites?

Abstract

Rossby waves play a key role in large-scale circulation, controlling the western boundary currents. In a baroclinic model they are prone to variability when changes in stratification occurs. In the present study these waves were identified at 11\oS, 24.5\oS~and 34.5\oS~in Atlantic, Pacific and Indian oceans. We noted that waves' amplitude varied significantly among the three basins, and we propose that stratification might play an important role on this difference. Brunt-Väisälä frequencies were calculated as a function of depth at these latitudes, and differences between ocean basins were observed. Vertical mode decomposition was done to characterize waves vertically to relate the surface signal with the water column. In this context, the main idea is to compare the vertical modes obtained by tradicional quasi-geostrophic modes to the surface quasi-geostrophic (SQG) solutions, to assess which signal the altimeter is representing. Therefore, our intention is to assess the role played by stratification in the amplitude of Rossby waves, comparing data from the three ocean basins at the above mentioned latitudes. Besides that, we aim to see 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)