MESOSCALE DATA ASSIMILATION STUDIES IN THE MIDDLE ADRIATIC SEA

In this paper we describe a mesoscale data assimilation experiment in the Middle Adriatic Sea. In order to perform dynamical forecasts we pr ovide a quasigeostrophic numerical model with a set of initial fields regularly gridded via an objective analysis technique. Maps of this in itial condition show a surface intensified jet meandering around a cyc lonic eddy at the thermocline and deep levels. We dynamically forecast ed the flow evolution for 30 days after initialization. The time scale of the variability is of the order of a few weeks and the cyclonic vo rtex seems to be locked to the topography. A set of numerical experime nts with different initial bottom boundary conditions, with and withou t topography, are made to explore the influence of the topographic con straint on the mesoscale flow evolution. As expected the influence of the topography on the dynamical evolution of the flow is very strong a nd it confines the jet-cyclone along the bathymetric contours, strengt hening the flow. On the other hand the flow is not sensitive to change s in the density bottom initial condition.Finally we analyze the energ y and vorticity fields of the 1-month dynamical forecast experiment. I t is concluded that a local frontogenetic process consisting of jet st rengthening and cyclone development occurs and that available gravitat ional energy is converted into kinetic energy during the process.