On the mediterranean water composition

20 páginas, 5 tablas, 6 figuras, 1 apéndice.-- Proyecto Carbochange

The Mediterranean Outflow Water (MOW) spills from the Mediterranean Sea (east North Atlantic basin) west off the Strait ofGibraltar.AsMOWoutflows, it entrains eastern NorthAtlantic CentralWaters (ENACW) and IntermediateWaters to formthe neutrally buoyantMediterraneanWater (MW) that can be traced over the entire NorthAtlantic basin. Its high salinity content influences the thermohaline properties of the intermediate– deepwater column in theNorthAtlantic and its dynamics.Here, the composition ofMWin its source region (the Gulf of Cádiz, west off Strait of Gibraltar) is investigated on the basis of an optimum multiparameter analysis. The results obtained indicate that mixing of MOW (34.1% 6 0.3%) occurs mainly with overlying ENACW (57.1% 6 0.8%) in a process broadly known as central water entrainment. A diluted form (80% of dilution) of the Antarctic Intermediate Water (AAIW) reaches the region and also takes part in MW formation (8.3% 6 0.5%). Finally, the underlying Labrador Sea Water (LSW) also contributes (0.4%6 0.1%) to the characteristics ofMW. Fromthese results and considering 0.74 Sverdrups (Sv; 1 Sv[ 106m3 s21) as themean outflow ofMOW, the MW exportation rate was inferred (2.2 Sv), which, decomposing MW, means that the MOW outflow is accompanied by 1.24 Sv of entrained ENACW, 0.18 Sv of AAIW, and ,0.01 Sv of LSW.

The research was supported through the Seventh Framework Program (EU FP7 Project CARBOCHANGE, ‘‘Changes in carbon uptake and emissions by oceans in a changing climate,’’ C_ENVIR/0869). All the authors were funded by the Spanish Research Council (CSIC). The first author was also partly financed by the Regional Government of Galicia through a specific program for short stays abroad, cofounded by the European Social Fund (FSE) 2011–15 and now is being funded by the University of Vigo, through the Galician I2C Plan for postdoctoral research

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