An Explanation for the Curvature of the Atlantic Jet past the Strait of Gibraltar

Abstract

A consistent explanation for the anticyclonic curvature of the Atlantic jet as it passes through the Strait of Gibraltar and flows into the Mediterranean Sea (eastern side of the strait) is provided. The anticyclonic curvature of the Atlantic jet, which is the key feature to understand the upper-layer circulation in the western Alboran Sea, is simply related to the positive net evaporation over the Mediterranean. The result of this positive net evaporation, that mainly occurs in areas of the Mediterranean far from the Strait of Gibraltar, is a net inflow transport through the strait. It is proposed that the positive net evaporation is able to produce such a net inflow in the strait because of an anomalous large-scale pressure gradient. This anomalous pressure gradient is found to be approximately collinear to the strait orientation. The time-averaged inflow of Atlantic water at the eastern side of the Strait of Gibraltar must therefore be supergeostrophic, and hence it must have anticyclonic curvature.