The role of the wind in the formation of coherent eddies in the Gulf of Eilat/Aqaba

Rare surface cyclonic eddies have been observed using a high frequency radar system in the northern part of the Gulf of Eilat/Aqaba. These surface eddies appear during fall and winter months and are absent during the rest of the year. Using an oceanic general circulation model and a regional atmospheric model (providing atmospheric wind with high spatial and temporal variability), we investigate the role of atmospheric wind in the formation and appearance of these eddies, by analyzing three cases in detail and by conducting idealized sensitivity experiments. For all three cases, the model simulates the development of a coherent eddy with similar characteristics as the observed ones, including width, intensity, and life-time. Generation of one of the coherent eddies occurs in a process similar to lid-driven cavity flow, in which eastward current at the southern open-boundary of the rectangular-shaped area of the head of the gulf drives the cyclonic circulation within the cavity. Other cases of eddy formation involve strong, northward flowing currents along the eastern boundary of the northern gulf. In all cases, weaker winds are favorable for the appearance of these eddies at the surface.