Marcel du Plessis
University of Cape Town, South Africa


Observing ocean-atmosphere interactions of the submesoscale field in the Southern Ocean


This study makes use of winter to autumn high-resolution profiling glider data collected in the Atlantic Subantarctic to assess the role of the submesoscale field in characterising the variability of the upper ocean. Frontal energetics make for a mixed layer environment with large horizontal density fronts present in the spring and summer months. We provide evidence that during this time, wind stress directed along a density front in the direction of the current induces a destabilising flux to reduce the upper ocean stratification. Conversely, quiescent wind phases along with up-front reversals are synonymous with an enhancement of upper ocean stratification. This restratifying flux is coherent with enhanced horizontal density gradients within the mixed layer. In addition to these findings, potential vorticity estimates provide information regarding the stability of the flow. Mixing phases indicate a highly unstable mixed layer, while the restratification of the mixed layer returns the potential vorticity to a stable state. These results promote the importance of horizontal density gradients and winds in the Southern Ocean, which are important in determining the stability of the mixed layer, and could have an important influence on the biogeochemistry and carbon fluxes.

Time and place
Friday 11 November 2016, 11.15
Rossbysalen, Arrhenius Laboratory, 6th floor