Circulation and hydrography of the Levantine Basin. Results of POEM coordinated experiments 1985–1986

Abstract

A brief review of the meteorological setting, hydrography and the circulation in the Levantine Basin of the Eastern Mediterranean is given. The recent high resolution data obtained in POEM coordinated experiments of 1985–1986 are then used to optimally estimate the circulation in the basin in two different seasons and to describe the water mass distributions. Some of the features observed during the experiments support the historical knowledge on the locations of sub-basin scale gyres and the general circulation, in addition to which some new features are established. Details of the circulation such as the intensity, the multiple scales and the three dimensional structure of the various vortices and the Central Levantine Basin Current are displayed extensively. A variety of sub-basin, meso- and sub-mesoscale vortices occur with highly assymmetric (baroclinic) vertical structures. Some eddies split into multiple centres with depth, interpreted as indicating possible coalescences. A number of long-lived eddies were persistent in both surveys. The sub-surface Atlantic Water (AW) is advected by and entrapped within the eddy field. The Levantine Intermediate Water (LIW) at intermediate depths is shown to be maintained throughout the year in the northeastern sector of the Levantine Basin and along the periphery of the Rhodes gyre. The Levantine Intermediate Water also has a patchy distribution, owing to the advection and trapping by the eddy field which it helps to generate through adjustment processes.