Tyrrhenian Sea circulation and water mass fluxes in spring 2004: Observations and model results

Hydrological and current measurements, collected in the Tyrrhenian Sea during May-June 2004, are analyzed with an inverse box model (IBM) to establish the mean circulation patterns of the basin during spring 2004. These patterns are compared with those provided by a high-resolution, primitive equation model (the Princeton ocean model, or POM) implemented over the area to simulate the mean basin circulation during the survey. The good agreement between the two circulation fields, despite the differences and the respective limitations of the employed methods, represents solid evidence for the reliability of the estimated dynamical structures. Moreover, the POM reveals the short spatial variability of the basin not always resolved by IBM because of the low spatial resolution of the in situ measurements. The comparative study indicates the Tyrrhenian basin as an extremely active region of the Mediterranean Sea, characterized by a rich mesoscale dynamics. This work provides, for the first time after more than 25 years, a novel qualitative assessment of the Tyrrhenian Sea spring circulation, together with a robust quantitative estimation of the water mass stream fluxes inside the basin and of the exchanges with the adjacent regions.