Oceanographic properties and circulation in the Adriatic Sea
Adriatic Sea is a northernmost sub-basin of the Mediterranean, thus influenced strongly by the cold continental air outbreaks in winter (bora wind). At the same time, it is characterized by the pronounced riverine run-off representing a dilution basin (source of the low salinity water) for the neighboring Ionian Sea. Cold and dry winter air outbreaks are responsible for the dense water formation which then spreads through the Strait of Otranto over the entire Eastern Mediterranean. The key role of the Adriatic is thus that it represents a source of the water for the renewal and oxygenation of the bottom layer of the Eastern Mediterranean sub-basin. On the other hand, the Ionian and Eastern Mediterranean waters enter the Adriatic bringing salt and heat. The Strait of Otranto is the area where this exchange takes place reaching about 1.000.000 m3/sec. Due to this exchange the circulation within the Adriatic is counterclockwise where salty and relatively warm waters of the Mediterranean origin spreads along its eastern coast northwestward. The return fresher water flow spreads southeastward along the western coastal shelf. Interaction with the Ionian Sea varies on decadal scale bringing into the Adriatic saltier Levantine waters or lower salinity waters of the Western Mediterranean and Atlantic origin. This is then responsible for the variations of the Adriatic nutrient content as well as the transport of organisms coming either from the Levantine Sea or from the Atlantic Ocean.