There is ample evidence that the mesoscale to sub-mesoscale variability in the ocean is still not adequately resolved nor is its impact fully accounted for in the present ocean and coupled ocean-biological models, in particular in the upper ocean layers. The decay of mesoscale structures is generally too fast, and turbulent fluxes of tracer are systematically underestimated, especially in the vertical. These processes typically occur at horizontal spatial resolutions from order 100 m to several kilometers, but their ranges of influence are propagating to coarser spatial scales (20-50 km). The optimum use of high-resolution satellite sensor synergy is therefore vital to improve the understanding of processes at these finer scales (order kilometer), as adequate in-situ observations resolving these scales are usually rare, and key recent theoretical and numerical results provide novel perspectives.

The 2Dto3D project targets this knowledge gap with an overall goal to develop and apply an innovative synergetic approach to quantify and describe, assess and monitor mesoscale to sub-mesoscale dynamics in the upper ocean based on systematic and consistent use of high-resolution satellite data, in-situ observations, and numerical simulations.

Indeed, the understanding of upper layer oceanic processes and interactions, including mutual feedback mechanisms, has rapidly evolved over the last few years. Specifically, recent very high resolution non-hydrostatic numerical model simulations have revealed that the dynamics in the upper layers might be diagnosed using a more advanced dynamical framework, i.e. a 3- Dimensional (3-D) framework that significantly departs from the 2-Dimensional (2-D) turbulence. Such demonstrations offer major prospects for the interpretation and integrated use of high-resolution satellite data. Accordingly, a novel and challenging perspective is the possibility to consistently use high resolution (1-5 km) satellite information of surface quantities, not only to retrieve estimates of the surface current, but also to reconstruct the mesoscale to submesoscale 3-D dynamics in the upper 200-500 m, including the vertical velocities. We shall thus strongly advocate the potential of a synergetic and integrated approach to consistently fuse satellite information (high resolution sea surface temperature, sun glitter reflectance, ocean color and radar images, and lower resolution sea surface topography and scatterometry observations) with in situ measurements and fine resolution numerical process models to fill in the 20-100 km “altimetry gap”.