Three-Dimensional Structure and Dynamics of Coastal Eddy Dipoles in the Southeastern Baltic Sea: Results of Remote Sensing and Oceanographic Experiments in Summer 2021

Abstract

The results of quasi-synchronous satellite and experimental field observations of two submesoscale eddy dipoles in the coastal zone of the southeastern Baltic Sea near the coast of Kaliningrad Region are presented. The parameters of eddy dipole dynamics, namely, the duration of the process in the sea water and its propagation velocity and direction, as well as atmospheric conditions favorable for the occurrence of eddy dipoles, are determined from consecutive satellite images of high resolution. The characteristics of the three-dimensional structure of eddy dipoles are determined using the data of an acoustic current profiler and a hydrological probe obtained concurrently with satellite survey. The depth of vortical motion penetration into the water column is discussed and it is shown that such processes are not purely surface phenomena but have their influence down to a depth of 20 m and more. Direct measurements of current velocities and directions within particular parts of an eddy dipole demonstrate significantly greater dynamics of waters inside such formations compared to their displacement velocity. The differences in the anticyclonic and cyclonic parts of the dipoles are evaluated. Hydrological observations show the influence of the active cyclonic part of a dipole on surrounding waters manifested in both capture (rise) of deeper water and accumulation of surfactants within it.