Medelhavsvatten

Medelhavsvatten is a term used in oceanography to describe the seawater properties and water masses associated with the Mediterranean Sea. It encompasses the distinctive horizontal and vertical structure of the basin’s water, including the outflow of dense saline water into the Atlantic through the Strait of Gibraltar.

The Mediterranean experiences high evaporation relative to freshwater input, which raises salinity levels compared with open-ocean waters. Surface salinity typically lies around 37.5 to 38.5 practical salinity units (PSU), with values varying seasonally and by location. Temperatures in the upper layers can be warm in summer and cooler in winter, while deep waters remain relatively cold and very saline.

The basin is strongly stratified. In winter, dense water forms in the western basin, particularly near the Gulf of Lions, and sinks to the deep layers, creating Western Mediterranean Deep Water. This dense water propagates toward the Strait of Gibraltar and contributes to the Mediterranean Outflow Water that enters the Atlantic. In the eastern basin, intermediate and deep water masses, such as Levantine Intermediate Water, develop at different depths and contribute to the basin’s layered structure. Together, these water masses define the characteristic vertical profile of Medelhavsvatten.

Chemically, Medelhavsvatten tends to be oligotrophic in open areas, with relatively low surface nutrients but varying chemical signatures that reflect evaporation, riverine input, and deep-water formation. The physical properties of Medelhavsvatten influence gas solubility, nutrient distribution, and regional marine ecosystems.

Climate change and regional hydrology can alter evaporation rates, salinity gradients, and circulation patterns, affecting the formation and distribution of these Mediterranean water masses.