A coupled atmosphere-ocean model applied to the simulation of Mediterranean lows and hurricanes

This study aims to analyze the importance of the dynamics of the air-sea interface during intense events characterized by a strong air-sea interaction, i.e. large exchanges of heat, momentum and moisture. The study analyses and intercompares the results of the numerical simulation of a "Mediterranean Low" and a hurricane. The Mediterranean Lows are small scale systems, whose deepening crucially depends on the strong diabatic processes associated with the flow of Northern cold continental air above the warm Mediterranean Sea, mostly during autumn and early winter. Because of the strong air-sea fluxes and the development of deep convection in a well defined inner core, the dynamics of the Mediterranean Lows resemble the hurricanes, though with a much weaker intensity. The analyzed quantities include both atmospheric variables (sea level pressure, winds, precipitation, air temperature, etc. ) and oceanographic variables (sea level, sea temperature, currents, surface wave spectra, etc.). The numerical simulation is carried out with a tri-modular model (atmosphere+wave+ocean) called MIAO. The MIAO model computes the air-sea fluxes accounting for the feedbacks of the sea on the atmosphere. In this coupled model the sea surface temperature computed by the ocean circulation component and the sea surface roughness computed by ocean wave component are used by the atmospheric circulation component which, in turn, computes the surface fluxes of momentum, heat and moisture. The effect of the dependence of heat and moisture fluxes on the ocean waves, potentially important at high wind speeds, in also considered.