Observations of asymmetric turbulent stirring in inner and marginal seas using satellite imagery

Abstract

For the open ocean, it was already reported on the cyclonic (anticyclonic) asymmetry of appearance of eddies of a certain spatial scale. In this article, we scrutinize the ratios of mostly mesoscale cyclonic and anticyclonic eddies in a number of inner and marginal marine basins, namely in the Baltic, Black, North, and Western Mediterranean Seas. As research material, over 9700 eddy manifestations in the thermal infrared, visible-range, and radar satellite imagery were used. The analysis performed showed that in all the seas the typical and average values of the diameter of anticyclonic eddies were greater than those of cyclonic eddies. The main factor that defines the ratio between anticyclonic and cyclonic eddies in the basins under consideration was discovered to be the intensity of their surface currents. Thus, in the presence of a strong jet flow at the scales of about 2–4 baroclinic Rossby radii, the cyclonic eddy dominance typical for smaller eddies was replaced by the anticyclonic one. If strong jet streams were missing, as that typical of the Baltic Sea, cyclonic eddies were prevailing over the entire spectrum of eddy diameters.