The southwestern Atlantic Ocean mesoscale eddies: A review of their role in the air-sea interaction processes

Abstract

This study presents an overview of oceanic mesoscale eddies and their influence on the overlying atmosphere and surrounding waters, with a focus on the southwestern Atlantic Ocean. The high values of eddy kinetic energy (EKE) in this region are related to the mesoscale eddies observed, which transport dynamic and thermodynamic specific properties away from their origin point, during their life cycle. This transport capacity interferes with several atmospheric and oceanic processes, such as the local marine atmospheric boundary layer (MABL) stability, heat fluxes, and primary production. In the Southern Hemisphere, cyclonic (anticyclonic) eddies are related to clockwise (counterclockwise) circulation and negative (positive) anomalies of the sea surface temperature (SST) and the latent and sensible heat fluxes. It has been observed that over the clockwise and cold (counterclockwise and warm) eddies, there is a decrease (increase) in the near-surface wind, as well as stable (unstable) conditions on the MABL, vertical downward (upward) movements in the atmosphere, and decreased (increased) precipitation. SST anomalies influence the curl, divergence, and magnitude of the surface wind and wind stress, while mesoscale surface oceanic currents mainly affect the stress and wind curls. The atmospheric response to SST anomalies can be explained using two main mechanisms: hydrostatic adjustment and vertical mixing. However, as will be shown, the feedback among the SST anomalies, wind, and oceanic currents is far more complex. This work compiles and provides a theoretical basis for future work concerning air-sea interactions of mesoscale oceanic structures.