Jeudi 23 juin - On the relative contribution of interior mixing and air-sea fluxes to the Mediterranean Overturning Circulation
Jun 23, 2016
from 11:00 AM to 12:00 PM
Loic Jullion, Mediterranean Institute of Oceanography (MIO)
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Mediterranean Institute of Oceanography (MIO)
Title : On the relative contribution of interior mixing and air-sea fluxes to the Mediterranean Overturning Circulation
The Mediterranean Overturning Circulation is investigated by analyzing 32 years of an eddy-resolving regional ocean circulation model (NEMOMed12) in a potential temperature-salinity framework in order to better understand the processes driving water mass transformation. This framework allows a simple yet informative quantification of the relative contribution of air-sea fluxes and interior mixing to the water mass transformations. In temperature-only coordinates, this study shows the crucial role of taking into account the penetration of shortwave radiation in the ocean interior on the water mass transformation. In Salinity-only coordinates, the analysis reveal the existence of two main regimes, between the salinity of the Gibraltar inflow and outflow, the haline circulation is a balance between the salinity transport across Gibraltar and interior mixing while for the salinity higher than the Gibraltar outflow, the balance is between air-sea fluxes and mixing therefore suggesting that interior mixing is key to set the salinity of the Mediterranean outflow in the North Atlantic. Our results also suggest that the Sicily channel seems to be a key region in terms of interior mixing. This study highlights the need to better understand mixing processes, which have been notoriously under-studied in the Mediterranean Sea.