About the origin of the Mediterranean Waters warming during the twentieth century

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Dissolved organic nitrogen production and export by meridional overturning in the eastern subpolar North Atlantic

Research articleDissolved organic matter (DOM) is produced in the surface and exported towards the deep ocean, adding ∼ 2 PgC/year to the global carbon export. Due to its central role in the Meridional Overturning Circulation, the eastern subpolar North Atlantic (eSPNA) contributes largely to this export. Here we quantify the transport and budget of dissolved organic nitrogen (DON) in the eSPNA, in a box delimited by the OVIDE 2002 section and the Greenland-Iceland-Scotland sills. The Meridional Overturning Circulation exports >15.9 TgN/year of DON downward and, contrary to the extended view that these are materials of subtropical origin, up to 33% of the vertical flux derives from a net local DON production of 7.1 ± 2.6 TgN/year. The low C:N molar ratio of DOM production (7.4 ± 4.1) and the relatively short transit times in the eSPNA (3 ± 1 year) suggest that local biogeochemical transformations result in the injection of fresh bioavailable DOM to the deep ocean.Versión del editor3,79

The Effects of Climate Change and Rivers Damming in the Mediterranean Sea during the Twentieth Century

The Mediterranean Sea transforms Atlantic Waters inflowing through the Strait of Gibraltar into saltier, cooler and denser Mediterranean Waters that outflow into the Atlantic Ocean. A theoretical steady state functioning of the Mediterranean Sea would be the result of the balance between the net heat and volume transports through the Strait of Gibraltar and the heat loss to the atmosphere through the sea surface and the net evaporation. The salt transport for the inflow and outflow should be balanced. Changes in the heat content, temperature and salinity of the Mediterranean waters reveal that the present Mediterranean functioning is out of this equilibrium state. A new analysis for MEDAR data shows that the temperature and salinity averaged for the Mediterranean Waters in the whole basin increased at rates of 0.1 oC/100 yr and 0.02 psu/100 yr during the twentieth century. This temperature trend is equivalent to 0.14 W/m2 heat absorption. The analysis of RADMED monitoring program in the Spanish Mediterranean and the EN4 data set from the Met Office Hadley Center show that this warming and salting would have increased during the beginning of the twenty first century at the Western and Eastern Mediterranean (0.2 o C/100 yr, 0.09 psu/100 yr), maybe linked to the Western and Eastern Mediterranean Transients. Results from a simple box model using heat, volume and salt conservation laws indicate that the observed changes during the twentieth century cannot be attributed only to an increase of the net evaporation, nor to a salinity increase of the Atlantic Waters flowing through the Strait of Gibraltar as previous hypotheses suggested. A 3.5% increase in the net evaporation combined with a 0.4W/m2 reduction of the heat losses to the atmosphere could explain the observed changes

The effect of interpolation methods in temperature and salinity trends in the Western Mediterranean

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Relationships between Octopus vulgaris landings and environmental factors in the northern Alboran Sea (Southwestern Mediterranean)

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