On the relevance of tidal forcing in modelling the Mediterranean thermohaline circulation

The four dominant constituents of the semi-diurnal and diurnal tides have been implemented in a regional eddy-resolving Mediterranean version of the Massachusetts Institute of Technology general circulation model to assess the role played by tides on the simulated Mediterranean thermohaline circulation. To this aim we have compared two 10-year hindcast simulations differing only for the inclusion/omission of tidal forcing. Following the recent recommendations suggested by Sannino et al. (2014) both simulations use the same model having a substantial increment of the horizontal resolution in the region of the Strait of Gibraltar. The results suggest that application of explicit tidal forcing in a Mediterranean model has non negligible effects on the simulated circulation in addition to the expected intensification of local mixing processes. The western basin exhibits an immediate response to the different characteristics of the inflowing AW observable in the modified deep water convection processes in the Gulf of Lion. The inclusion of tidal forcing also induces changes in the intermediate circulation of the Tyrrhenian Sea bringing to a better representation of local structures and a reinforcement of the global thermohaline cell. LIW dispersal paths in the eastern basin are also affected by tides.