Characterizing the role of non-linear interactions in the transition to submesoscale dynamics at a dense filament

Ocean dynamics at the submesoscale play a key role in mediating upper-ocean energy dissipation and dispersion of tracers. Observations of ocean currents from synoptic mesoscale surveys at submesoscale resolution (250 m–100 km) from a novel airborne instrument (MASS DoppVis) reveal that the kinetic energy spectrum in the California Current System is nearly continuous from 100 km to sub-kilometer scales, with a k-2 spectral slope. Although there is not a transition in the kinetic energy spectral slope, there is a transition in the dynamics to non-linear interactions at scales of O(1 km). Barotropic kinetic energy transfer across spatial scales is enabled by interactions between the rotational and divergent components of the flow field at the submesoscale. Kinetic energy flux is intermittent but can be large, particularly at submesoscale fronts. Kinetic energy is transferred both downscale and upscale from 1 km in the observations of a cold filament.