Chapter 8 - Submesoscale processes and mixing

Abstract

In this chapter, we discuss the links between oceanic submesoscale (100 m–10 km) processes and mixing. Submesoscale currents occur on lateral scales of 100 m–10 km in the ocean and are associated with density fronts and filaments, vortices and topographic wakes at the surface and in the ocean's interior. In most cases, submesoscale processes do not directly contribute to mixing, however they have an important role in cascading energy and tracer variance from the largely adiabatic mesoscale down to the scales at which diapycnal mixing can occur. Submesoscale currents redistribute water properties, including buoyancy, momentum, heat, freshwater, and biogeochemical tracers. While submesoscale instabilities enhance vertical exchange, they drive an efficient restratification of the upper ocean. They can also have a strong impact in the bottom boundary layer, where they generate turbulent mixing and export mixed waters out of the bottom boundary layer.