Investigation of fine spatial structure of currents and submesoscale eddies based on satellite radar data and concurrent acoustic measurements

Satellite high-resolution radar data from Envisat ASAR, RADARSAT-2 and TerraSAR-X sensors are used for the detection and investigation of fine structure of currents and submesoscale eddies. The fine structure of sea currents is manifested in radar images as quasiperiodic slick strips of a horizontal scale from tens of meters to several kilometers. The strips are typically elongated along the currents apparently indicating their jet character and intermittence. The focus is on filamentary slick bands involved into small scale vortical processes and allowing estimation of spatial characteristics of submesoscale eddies based on their SAR signatures. Submesoscale or eddies with diameters of less than Rossby radius of deformation could hardly be investigated by traditional oceanographic means due to spontaneity of their appearance, nonstationarity and short lifetimes. Sources of their generation are still not well known. A large archive of satellite data accumulated during 1999-2011 over different parts of the Black, Baltic and Caspian Seas has been analyzed in order to search, systemize and reveal mechanisms of formation and evolution of small scale eddy structures in these areas. Atmospheric and hydrological fronts and current instability have been found to play a significant role in submesoscale eddies generation. Subsatellite measurements using acoustic Doppler profiler (ADCP) have been performed aimed at verification and adjustment of the results obtained based on satellite radar data. The formation and drift of a near-shore submesoscale anticyclonic eddies of 5-7 km in diameter were observed.