Deep chlorophyll Maximum distribution in the central Tyrrhenian Sea described by a towed undulating vehicle.

The towed undulating vehicle (TUV), named SARAGO, was used for two fine-scale surveys between thè Ilalian and thè Sardinian coasts during thè Astraea 2 cruise (6-7 and 26-27 September 1995), studying thè deep chlorophyll maximum distribution. SARAGO sections identify a sub-surface doming with higher chlorophyll a and primary production concentrations in thè upwelling area of a cyclonic gyre region, detected by sea-surface temperature images. In thè first section, thè cyclone presents a doublé doming, in density and salinity, with shallower and concentrated patches of chlorophyll a for about 2 miles. Twenty days later, thè second section shows that thè gyre changes shape and extension, showing a single doming with higher primary production and chlorophyll a concentrations, distributed over a large area of about 40 nautical miles. SARAGO allows analysis of this high-variability phenomenon (cyclonic gyre) and allows concentrated patches (2 nm) to be identified, thus proving thè importance of TUVs in thè study of mesoscale processes.