MERIS VIS roughness image contrast under Sun glitter conditions collected over the Mediterranean Sea Islands (Malta) outlined in black. Scene is roughly 150 km2 and brightness contrasts clearly display surface expressions of linear frontal features, meanders, and eddies with widths ranging from 1 to 10 km.
Over the recent years, several very high resolution numerical simulations of the ocean have been performed in large domain to confirm the strong dynamical impact of submesoscales (e.g. Klein et al., 2009). As uncovered, it is now anticipated that the 3D "adiabatic" dynamics within the first 500m below the ocean upper mixed layer would be very efficiently diagnosed using high resolution sea surface height (SSH) observations, and climatological in-situ data, using a Surface Quasi-Geostrophy/Quasi-Geostrophy (SQG/QG) framework.
To go beyond these results, the main objective of the O3S project is then to address the following questions :
- Can the 3D "adiabatic" dynamics within the ocean upper-mixed layer forced by intermittent air-sea fluxes be diagnosed from space?
- What additional satellite observations other than high resolution SSH (such as sea surface temperature (SST), optical and roughness properties, sea surface wind vector (SWV) and waves) are needed ?
Based on encouraging first recent results of the proposal team members, testing how much upper ocean mixed-layer currents, embedded in rich meso and submesoscale eddy fields, depart from geostrophy (e.g. Sasaki and Klein, 2012, Klein et al., to be submitted, Kudryavtsev et al., 2012), the subsequent research efforts, addressed in this project, are:
- to dwell on a new advanced framework (based on numerical testbeds and theoretical concepts) to diagnose the upper ocean dynamics including the mixed-layer interior,
- to possibly enrich knowledge of the upper-layer mixing with surface wave dynamics, e.g. wave-current interactions, wave-turbulence and wave breaking dynamics,
- to investigate and implement new means to optimally combine multi-altimeter measurements with other satellite high-resolution measurements (e.g. SST snapshots, ocean optical and roughness properties), medium-resolution observations (e.g., (microwave sea surface temperature and salinity, scatterometer winds)
- to help to validate the diagnosis method of 3D dynamics using a combination of satellite multi-sensor observations (SSH, SST, ocean color and sea surface salinity, roughness) with high resolution in-situ data (temperature, salinity, ...) collected by instrumented elephant seals,
- to provide, using the growing available in-situ data (such as the Argo float data), improved horizontal and vertical fluxes of kinetic energy and tracers.
Motivations of O3S is to gain insights and understandings on the extent to which an advanced integrated use of combined satellite ocean surface data, limited subsurface data, and numerical simulations, can properly describe the complete 3-dimensional (3-D) upper-ocean dynamics at high resolution. Goals are to extend the SQG/QG theory using all available observations in different oceanic regions and to assess under which environmental conditions and ocean spatial scales, a new dynamical explanation is pertinent to also diagnose the 3D upper mixed-layer dynamics. This is the rationale to propose a set of innovative methods to monitor the ocean's interior using a satellite sensor synergy approach, as well as to anticipate and exploit future high resolution measured SSH variability.