The Mediterranean Sea Overturning Circulation

Nadia Pinardi, University of Bologna, Bologna, Italy, Paola Cessi, University of California San Diego, Scripps Institution of Oceanography, La Jolla, CA, United States, Federica Borile, University of Bologna, Physics and Astronomy, Bologna, Italy and Christopher Wolfe, Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook, United States
Abstract:
The time-mean zonal and meridional overturning circulations of the entire Mediterranean Sea are studied in both the Eulerian and residual frameworks. The overturning is characterized by cells in the vertical and either zonal or meridional planes with clockwise circulations in the upper water column and counterclockwise circulations in the deep and abyssal regions. The zonal overturning is composed of an upper clockwise cell in the top 600 m of the water column related to the classical Wust cell and two additional deep clockwise cells, one corresponding to the outflow of the dense Aegean water during the Eastern Mediterranean Transient (EMT) and the other associated with dense water formation in the Rhodes gyre. The variability of the zonal overturning before, during and after the EMT is discussed. The meridional basin-wide overturning is composed of clockwise, multicentered cells connected with the four northern deep ocean formation areas, located in the Eastern and Western basins.
The connection between the Wust cell and the meridional overturning is visualized through the horizontal velocities vertically integrated across two layers above 600m. The component of the horizontal velocity associated with the overturning is isolated by computing the divergent components of the vertically integrated velocities forced by the inflow/outflow at the Strait of Gibraltar.