Ocean mesoscale eddies and vertical motion

Oceanic mesoscale eddies are energetic features where strong three-dimensional circulations are set up and consequently enhanced biological activity take place. Indeed, vertical circulation associated with mesoscale eddies is of great importance as it may explain the patchiness of chlorophyll in the surface layers of the ocean. This work is focused on the estimation and analysis of the vertical exchanges associated with mesoscale dynamics and of their interannual variability, concentrating on selected areas of the World Ocean. We compute vertical velocities by integrating the quasi-geostrophic omega equation from a purely observational approach i.e., using the 3D fields of temperature and salinity derived from the ARMOR3D reanalysis that combines satellite (SST and altimetry) and in-situ (Argo profiling floats, XBT, CTD and moorings) data. The variability of the vertical velocity field is analyzed and the potential links between the observed signals and surface chlorophyll using tools for eddy identification and tracking are also investigated. This study is a contribution towards improving our understanding of the net effect of mesoscale variability on water mass formation and transport at global scale, as well as on its impact on the biochemical tracer redistribution and consequent marine ecosystem response.