CIRCULATION IN THE SURFACE AND INTERMEDIATE LAYERS OF THE BLACK-SEA

Abstract

Circulation features of the Black Sea are presented based upon a basin-scale survey carried out in September-October 1990. The circulation pattern for the upper 300-400 dbar consists of a cyclonically meandering Rim Current, a series of anticyclonic eddies confined between the coast and the Rim Current, and a basin-wide, multi-centered cyclonic cell in the interior of the basin. In contrast to prior investigations, although the currents are much weaker as compared with those in the upper layer, the intermediate depth (defined here between 500 and 1000 dbar) circulations reveal considerable structural variability. This involves counter-currents, shift of eddy centers, coalescence of eddies, and associated sub-basin-scale recirculation cells separated by the meandering Mid-Basin Current system. A descriptive synthesis of the upper layer circulation, combining the present results with earlier findings, identifies the quasi-permanent and recurrent features even though the shape, position, strength of eddies and meander pattern, and the bifurcation structure of currents vary.