Flow Patterns of the Main Water Masses Across Transversal Areas in the Southern Adriatic Sea: Seasonal Variability

Abstract

The results here presented regard four seasonal multidisciplinary surveys conducted in the Southern Adriatic basin, in the framework of the collaborative research program PRISMA (Programma di Ricerca e Sperimentazione del Mare Adriatico), with the aim of investigating the longitudinal fluxes across a series of significant transverse sections. The thermohaline properties of the main water masses and their seasonal and spatial variability over an entire annual cycle were analyzed. Five water masses take part in these processes; namely the Adriatic Surface Water (ASW), the Ionian Surface Water (ISW), the Levantine Intermediate Water (LIW), the Adriatic Deep Water (ADW), which overflows the Sill of Otranto to form the main component of the Eastern Mediterranean Deep Water, and finally the Northern Adriatic Dense Water (NADW). In order to follow the spatial extension of these water masses and their seasonal variability, the distribution of thermohaline properties along the transverse sections were considered. The major results concern the advection of the NADW, which has been observed to flow southward over the Pelagosa Sill and subsequently into the southernmost western shelf area, reaching the Otranto Strait. The horizontal thermohaline fields, objectively analyzed, show the main pathways of the above-mentioned water masses. Important signals in the seasonal variability of the baroclinic basin-wide circulation have been noted. Finally, a quantitative measure of the cross-sectional areas occupied by the intermediate and deep waters along the transverse sections located at the Gargano passage and Otranto Strait have been calculated and are discussed.