Lagrangian reconstructions of surface ocean turbulence

The characterization of submesoscale dynamics is crucial to apprehend their impact on the global ocean properties. Direct measurements of fine structures over the world oceans, nevertheless, are at present limited by the spatial resolution of satellite products. A method for the reconstruction of the small scales of tracer fields is here numerically studied. Tracers are reconstructed using a Lagrangian technique based on the property of chaotic advection by large (mesoscale) eddies to generate small scales from a low-resolution tracer field. The capabilities of the method are investigated in the context of a forced turbulent flow in the Surface Quasi Geostrophic (SQG) regime. Both qualitative and quantitative comparisons are performed between the original (high resolution) fields and their reconstructions that use only low-resolution data. Good agreement is found, with an optimal reconstruction time of the order of few eddy turnover times. Moreover, the statistics of tracer gradients, which are relevant for assessing the possibility to detect fronts, are found to be accurately reproduced.