Terms Of Reference

A rich tapestry of oceanic processes is manifest at scales O(0.1-10 km), small enough for the constraints of the earth’s rotation and oceanic stratification to be overcome, but larger than that of three-dimensional turbulence. Rossby and Richardson numbers of O(1) lead to a range of dynamical instabilities that respond to surface forcing and boundary stresses, and interact with the mesoscale flow field, upper ocean turbulence, and near-inertial waves. These dynamics result in enhanced vertical velocities and mixing, as well as stratification, on time scales that range from a few days to the inertial period and intersect with the time scales of internal waves and tides.

Their diagnoses is facilitated through advances in high-resolution autonomous, in-situ and remotely sensed observations, modeling, and theoretical advances. Their implications are wide-ranging and include the transfer of energy across scales, lateral mixing and transport, restructuring of the upper ocean’s density and stratification, modulation of air-sea, ice-ocean, ocean-bathymetric interactions, the exchange of biogeochemical properties across the mixed layer base, vertical supply of nutrients for primary production, modulation of light exposure and growth rates for phytoplankton, subduction of surface water, and export of particulate organic carbon and oxygen from the surface mixed layer. The similarity of physical and biological time scales of phytoplankton growth heightens the relevance of submesoscale processes for the production and export of phytoplankton, and the structuring and diversity of oceanic ecosystems.

This colloquium aims to advance our collective understanding of submesoscale processes, their mechanistic functioning, relevance, and implications across a range of oceanic disciplines. Discussions will include observational, modeling and theoretical approaches for elucidating submesoscale phenomena. From this colloquium, its oral/poster presentations and scientific interactions, will emerge new cross-cutting themes for future research.

Topics that will be addressed include:

• Dynamics of frontal and mixed-layer instabilities (forced and unforced) and their implications.
• Impact of winds and surface forcing on the mixed layer and submesoscale instabilities.
• Surface boundary layer turbulence and submesoscale instabilities, large-eddy simulation and observations of surface waves, Langmuir circulations. Their implications for air-sea coupling.
• Surface signatures of submesoscale dynamics from remotely sensed surface topography, roughness, and ocean color.
• Mesoscale-submesoscale interactions, energy cascades, impact of submesoscales on larger/smaller scales
• Physical-biological interactions — implications for biogeochemistry, productivity, export, ecosystem structure and diversity
• Freshwater in the oceans — implications of submesoscale processes for sea ice, river plumes and freshwater dispersal
• Coastal submesoscale dynamics — interaction with topography and the bottom boundary
• Wave-front/eddy interactions Interaction of internal waves and submesoscale fronts/ eddies
• Modelling issues related to multi-scale and multi-physics nature of the processes and in particular model nesting, unstructured grids and developments of new discretization schemes.