Influence of the atmospheric pressure fluctuations over the Mediterranean Sea on the mesoscale water dynamics of the Strait of Gibraltar and the Alboran Sea

The effect of subinertial sea level atmospheric pressure fluctuations on the inflow intensity of the surface Atlantic waters through the Strait of Gibraltar and its impacts on the dynamics of the Alboran Sea is studied. The results confirm that the exchange flows in the Strait is affected by atmospheric processes of much larger spatial scale than the Strait of Gibraltar itself. The Ligurian Sea is the region where atmospheric pressure fluctuations correlate better with Atlantic inflow anomalies through the Strait of Gibraltar. Correlation between in situ measurements of the surface flow velocity in the Strait of Gibraltar and NCEP-CFSR reanalysis data of the atmospheric pressure for the whole Mediterranean basin shows that a decrease of atmospheric pressure in the Ligurian Sea leads to an intensification of the Atlantic water inflow, and conversely, an increase of atmospheric pressure to a decrease. The hypothesis about the remote effect of atmospheric pressure fluctuations in the Atlantic water inflow through the Strait of Gibraltar is confirmed by the results of a simulation based on a one-dimensional hydrodynamic model. The subinertial variability of the Atlantic inflow induced by atmospheric pressure fluctuations has an impact on the formation of the mesoscale dynamics of the Alboran Sea. This is confirmed by an analysis of the HF-radar surface current measurements in the Alboran Sea and satellite observations of chlorophyll-a concentration.

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