Surface circulation of the eastern Mediterranean Levantine basin: Insights from analyzing 14 years of satellite altimetry data

The complex multiscale system circulation of the Levantine Eastern Mediterranean (EM) basin is analyzed by applying various spatiotemporal statistical methods on the AVISO 14 years (1993-2006) data set of satellite altimetry sea level anomalies. The Rossby deformation radius at the EM is at the order of 10 km, which is also the horizontal satellite resolution. Therefore, the geostrophic currents, derived from the satellite altimetry measurements, represent well the basin and the mesoscale circulations. The long-term averaged mean dynamic topography (MDT) is found to capture the different eddy activity regions in the EM; however, these regions are highly turbulent. The instantaneous currents in these regions can be different from the MDT-derived currents, by the same order of magnitude. Furthermore, the turbulence intensity appears to be nonperiodic, despite of the seasonal and long-term steric periodic variability. Because these eddies interact with the basin circulation flow, they modify it continuously. The major exception of this sporadic behavior is the Ierapetra eddy, southeast of Crete. It appears to be forced by shear of the summer Etesian winds, created when the Crete mountain ridges block these winds and cause a funneling effect. It has a persistent seasonal signature that dominates the variance of the entire Levantine basin.