On the hydrographic determination of coastal current: the case of the Central Tyrrhenian Sea (Western Mediterranean Sea).

A classical difficulty concerning coastal currents is the computationof geostrophic velocities for the shelf regions shallower than the no-motion level. For the case of the central Tyrrhenian sea (Western Mediterranean), we extrapolated the real isopycnals in a vertical sectioninto the sea bottom by applying the classical methods of Helland Hansen and Groen. This also allowed us to compute the two types of dynamic heights for the shallowest coastal region, with interesting results. The most interesting aspect is that the scatterplots of dynamic heights versus the density stratification give a constant-stratification flow for the innermost coastal current. This result is in agreement with the theoretical picture of one layer of marine water with constant stratification flowing along-shore over the innermost part of the shelf, namely of density-driven coastal current.