Circulation over the southeastern continental shelf and slope of the Mediterranean Sea: Direct current measurements, winds, and numerical model simulations

Abstract

Results are presented for the first time from an extensive, systematic campaign of direct current measurements that were conducted over the continental shelf and slope of the southeastern corner of the Mediterranean over a 10‐year period. Concurrent cross‐shelf hydrographic transects and coastal wind measurements were also conducted. The results are presented within the context of the general circulation of the Levantine Basin as simulated with a numerical model. The circulation over the shelf is northward throughout the year with strong seasonal variability, and maximum currents in winter and summer. In summer, the strong currents are confined to the upper layer with seaward intensification. Over the slope, a seasonally varying along‐slope baroclinic jet also appears during summer and early winter. The shelf and slope current system is part of the general circulation of the Levantine basin composed of the bifurcating Atlantic Ionian Stream, the Mid‐Mediterranean Jet, and the cyclonic basin‐wide current that follows the coast. During winter storms, the strong southwesterly winds drive the northward flowing current and downwelling over the shelf. At this time the deeper level currents near the shelf break are also intensified. The alongshore synoptic currents are weakly coherent and strongly affected by the alongshore pressure gradient. In late winter the slope jet remains offshore and does not intrude over the narrow shelf. Both the measurements and the simulations confirm the strong seasonality and variability of the shelf and slope current system and hint at the potential for intense shelf‐open sea exchanges in this region.