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Internal tides are studied in the central Mediterranean Sea using observational data and numerical experiments. Both numerical results and observations indicate that the baroclinic variability in this area is dominated by the K1 diurnal tide. In agreement with previous studies, the diurnal internal tides have the characteristics of Kelvin-like bottom trapped waves. They are mainly generated by the interaction of the induced barotropic tidal flow with the steep bathymetric gradient connecting the Ionian Sea with the shallow Sicily Channel. The bathymetric gradient appears to be the major forcing shaping the propagation paths of the internal tides. The most energetic internal tides follow the steep bathymetric gradient, propagating southward and tending to dissipate rapidly. Other waves cross the continental shelf south of Malta and then split with one branch moving toward the southern coast of Sicily and the other moving toward the west. Internal tides propagate with a variable phase velocity of about 1 ms−1 and a wavelength of the order of 100 km. During their journey, the internal waves appear to be subject to local processes that can modify their characteristics. The induced vertical shear strongly dominates the vertical turbulence and generates vertical mixing that alters the properties of the water masses traversing the area. Barotropic and internal tides remove heat from the ocean surface, increasing atmospheric heating, and redistributing energy through increased lateral heat fluxes. Lateral heat fluxes are significantly greater in the presence of internal tides due to the simultaneous increase in volume fluxes and water temperatures. [ABSTRACT FROM AUTHOR]

Climatic changes and interannual variability in the Mediterranean overturning circulation are crucially linked to dense water formation in the Levantine Sea, namely the Levantine Intermediate Water whose formation zone, comprising multiple and intermittent sources, extends over fluctuating pathways. To probe into the variability of this water formation and spreading, a unique dataset was collected during the winter of 2019 in the western Levantine Sea, via oceanographic cruises, profiling floats and a glider, at a spatio-temporal distribution suited to resolve mesoscale circulation features and intermittent convection events. This study highlights the competition between two source regions, the Cretan Sea and the Rhodes Cyclonic Gyre, to supply the Mediterranean overturning circulation in Levantine Intermediate Water. The Cretan source was estimated as the most abundant, supported by increasingly saltier water masses coming from the Levantine Sea under the pumping effect of a water deficit caused by strong western outflow toward the Ionian Sea. [ABSTRACT FROM AUTHOR]

Drifters and a glider were operated in the southeastern Ligurian Sea to study the near-surface currents and water mass properties in summer 2010. Additional data were collected by a moored current meter in the Corsica Channel (CC). These in situ data were complemented by surface wind products, satellite images of ocean color and a Regional Ocean Modeling System (ROMS) numerical model that was implemented to simulate the local coastal dynamics. Southward currents were prevailing along the continental Italian coast, advecting filaments with a high optical signal coming from the Arno River. North of Elba Island, currents turned westward and northward in the vicinity of the CC. Further to the north they veered eastward, forming an anticyclonic circulation feature centered around Capraia Island. This general circulation picture was disrupted and reversed during events of sustained southerly winds occurring with a period of about a week. The near-surface currents in the CC and the anticyclonic circulation around Capraia Island showed the same weekly variations related to the local wind forcing. The ROMS model simulations agreed satisfactorily with the observations, in particular the strength of the Capraia anticyclonic circulation (quantified with the Capraia index) was confirmed to be strongly wind-dependent. • The surface circulation in the southeastern Ligurian Sea is strongly wind-dependent. • Anticyclonic circulation around Capraia Island is predominant. • Currents transport offshore filaments of low-salinity and nutrient-rich waters of riverine origin. [ABSTRACT FROM AUTHOR]

The Vercelli Seamount is an undersea topographic feature of the northern Tyrrhenian Sea which rises from around 2000 m depth to almost the surface (55 m depth). In late spring 2009 the interdisciplinary experiment "Tyrrhenian Seamounts Ecosystems: an integrated study" was conducted around the seamount to investigate its influence on the hydrodynamics and the biogeochemical conditions of the area. As part of this integrated study a Slocum glider was operated around the seamount from 23 to 30 May, 2009 to sample the physical and biogeochemical characteristics of the water column from the sea surface down to 190 m depth. The observations revealed little influence of the seamount of the near-surface circulation and water mass characteristics. They showed, however, slanted sub-mesoscale structures below the thermocline in the southern area of the seamount. These features evidenced in different recorded parameters are approximately compensated in density. [ABSTRACT FROM AUTHOR]