Shear Instability and Turbulence Within a Submesoscale Front Following a Storm
Rodrigues, Arthur
Schultze, Larissa K. P.
Merckelbach, Lucas M.
Suzuki, Nobuhiro
Baschek, Burkard
Umlauf, Lars
DOI: https://doi.org/10.23689/fidgeo-4064
Schultze, Larissa K. P.; 1 Institute of Coastal Research Helmholtz‐Zentrum Geesthacht Geesthacht Germany
Merckelbach, Lucas M.; 1 Institute of Coastal Research Helmholtz‐Zentrum Geesthacht Geesthacht Germany
Suzuki, Nobuhiro; 1 Institute of Coastal Research Helmholtz‐Zentrum Geesthacht Geesthacht Germany
Baschek, Burkard; 1 Institute of Coastal Research Helmholtz‐Zentrum Geesthacht Geesthacht Germany
Umlauf, Lars; 2 Leibniz Institute for Baltic Sea Research Warnemünde Germany
Abstract
Narrow baroclinic fronts are observed in the surface mixed layer (SML) of the Baltic Sea following an autumn storm. The fronts are subjected to hydrodynamic instabilities that lead to submesoscale and turbulent motions while restratifying the SML. We describe observations from an ocean glider that combines currents, stratification, and turbulence microstructure in a high horizontal resolution (150–300 m) to analyze such fronts. The observations show that SML turbulence is strongly modulated by frontal activity, acting as both source and sink for turbulent kinetic energy. In particular, a direct route to turbulent dissipation within the front is linked to shear instability caused by elevated nongeostrophic shear. The turbulent dissipation of frontal kinetic energy is large enough that it could be a significant influence in the evolution of the front and demonstrates that small‐scale turbulence can act as a significant sink of submesoscale kinetic energy.
Key Points:
An autonomous ocean glider observed turbulence, currents, and stratification in surface mixed layer submesoscale fronts following a storm. Submesoscale fronts provide both a damping and generation of surface mixed layer turbulence. Shear instability within the front could represent a significant energy transfer in frontal evolution.