Why doesn't the Mediterranean dry up?
(MWN / 20-12-09) The Mediterranean Sea receives everyday, thorough the Strait of Gibraltar, an average of 4,752 cubic hectometre of water from the Atlantic Ocean, an amount that is equivalent to some more than two million Olympic swimming pools, and that prevents that this semi-closed sea dries up.
The arrival of the water is “vital” for the Mediterranean, since the evaporation in its surface is much higher than the contribution of rivers and rain. These are the conclusions of a novel study carried up by David Garcia, mathematician of the Space Geodesy Laboratory of Alicante University (UA).
This scientist has used data from satellite GRACE (Gravity Recovery and Climate Experient), which measures variations in t he Earth's gravitational field and was launched into orbit by the U.S. space agency (NASA) and the German agency (GFZ) in 2002. Isabel Vigo and José Manuel Ferrándiz (UA) and other scientists from Taiwan University and NASA have participated in this project.
Garcia has revealed that the data provided by this satellite over the last six years, combined with meteorological and hydrological models to calculate evaporation, precipitation and river inputs, conclude that the Mediterranean has a negative daily net of 4,752 cubic hectometres, which means that it “loses” 1,734,480 hm3 per year.
Nevertheless, the Mediterranean does not dry up because the lost of water caused by evaporation is compensated by water from the Atlantic Ocean through Gibraltar. Although there is also water that goes out to the Atlantic, the interchange clearly benefits the Mare Nostrum, with an average of 55,000 cubic meters per second, or 0.055 hm3, which is the same as 24 swimming pools 50 meters long by 25 meters wide and 2 meters high.
