On the response of a turbulent coastal buoyant current to wind events: the case of the Western Adriatic Current

Abstract

This numerical study focuses on the response of the Western Adriatic Current to wind forcing. The turbulent buoyant surface current is induced by the Po river outflow in the Adriatic Sea. Idealized and realistic wind conditions are considered by retaining the complex geomorphology of the middle Adriatic basin. In the absence of wind, the Adriatic Promontories force the current to separate from the coast and induce instabilities. Persistent 7-m s −1 downwelling favorable northwesterly winds thicken and narrow the current. Instabilities whose size is ∼ 10 km develop but ultimately vanish, since there is not enough across-shore space to grow. On the contrary, 7-m s −1 upwelling favorable southeasterly winds thin and widen the current, and instabilities can grow to form mesoscale (∼ 35 km) features. When realistic winds are considered, the same trends are observed, but the state of the sea set up by previous wind events also plays a crucial role. The turbulent regimes set up by different winds affect mixing and the WAC meridional transport. With downwelling winds, the transport is generally southward and mixing happens mostly between the fresher (S ≤ 38) salinity classes. With upwelling winds, the transport decreases and changes sign, and mixing mainly involves saltier (S > 38) waters. In all cases, mixing is enhanced when a finer 0.5-km horizontal resolution is employed.

Combining Litter Observations with a Regional Ocean Model to Identify Sources and Sinks of Floating Debris in a Semi-enclosed Basin: The Adriatic Sea

“…Carlson et al (2016) showed how synoptic wind events can alter surface Lagrangian pathways in the Adriatic and, as such, COSMO winds at 10 m height are use to qualitatively examine the role of winds in the transport of floating AMD, following Carlson et al (2016). Basin-averaged wind is used as previous studies found high correlations in both magnitude and direction of surface winds over the Adriatic (Magaldi et al, 2010;Carlson et al, 2016).…”

Downfront Winds over Buoyant Coastal Plumes

“…Whitney and Garvine (2005) derive and test a scaling for the relative importance of wind versus buoyancy for the Delaware Coastal Current and show that for realistic wind events the wind forcing can dominate the flow. Using realistic and idealized numerical models, Magaldi et al (2010) showed that downwelling-favorable winds over the West Adriatic Current (along the east coast of Italy) intensify and stabilize the current and also induce mixing that dilutes the freshwater plume.…”

Drowned karst landscape offshore the Apulian margin (Southern Adriatic Sea, Italy)

“…At water depths greater than 70 m, late-Holocene muddy deposits are draped on the pre-existing erosional morphology of the area (Cattaneo et al, 2003). Between the two areas of deposition, the flat area is barren of modern muddy late-Holocene sediment, suggesting that, in this region, the Adriatic Coastal Current accelerating around the Gargano Promontory does not allow permanent deposition of mud, as predicted by oceanographic models (Magaldi et al, 2010). The barren area is characterized by the presence of shell gravel, bioclastic sand, rhodoliths, live oyster aggregates, and by an area of outcropping cemented rocks with a high backscatter on sidescan sonar and a rugged topography suggestive of differentially cemented or differentially eroded stratified rocks.…”