Influence of the Icelandic Low on the Variability of Surface Air Temperature in the Gulf of Lion: Implications for Intermediate Water Formation

Abstract

The authors investigate the interannual variability of surface air temperature in the Gulf of Lion (northwestern Mediterranean Sea) during the winter season, which has been proposed as the dominant factor for the Mediterranean Intermediate Water (WIW) formation. Recent studies suggest that the variability of WIW formation in the Gulf of Lion can be partially explained by the North Atlantic Oscillation. To examine this process in more detail, the authors separate the North Atlantic Oscillation into two centers of action, the Azores high and the Icelandic low. This approach reveals that the pressure of the Icelandic low controls the surface air temperature in the Gulf of Lion, and the influence of the Azores high is insignificant. It is found that the winds over Europe are predominately northerly during winters with high pressure values of the Icelandic low. These conditions also correspond to colder air temperatures in the Gulf of Lion, which have been proposed previously to be correlated with ocean convection to intermediate depths.