The Response of Sea Level to Atmospheric Forcing in the Mediterranean

Abstract

Varying atmospheric pressure causes inversely proportional sea level changes. This is often called the "inverted barometer" effect. In cases of semi-enclosed seas, the response is limited by the configuration of the connecting straits. Three case studies demonstrating the complexity of the interaction between sea level and atmospheric forcing in the Mediterranean Sea are presented. Monthly and daily mean values of sea level, at atmospheric pressure and wind components at three stations are analysed in order to provide insight on the interactions at time scales from days to decades. The response of sea level to changing atmospheric pressure is frequency dependent and is almost never the theoretically predicted isostatic response of -1 cm of sea level change for 1 mbar change of pressure. The contribution of the wind components is found to be very small for most frequencies. Nevertheless, wind is found to be the dominant parameter characterizing the annual cycle in the north coasts of the Mediterranean.