A model analysis of the behavior of the mediterranean water in the north atlantic

• Published in: Journal of physical oceanography Vol. 37; no. 3; pp. 764 - 786
• Main Authors: YANLI JIA, COWARD, Andrew C, DE CUEVAS, Beverly A, WEBB, David J, DRIJFHOUT, Sybren S
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.03.2007
• Subjects: Boundary currents; Climate; Density; Earth, ocean, space; Entrainment; Exact sciences and technology; External geophysics; General circulation models; High temperature; Hypotheses; Marine; Modelling; North Atlantic Current; Ocean circulation; Ocean temperature; Oceanic general circulation model; Oceanography; Oceans; Outflow; Physics of the oceans; Salinity; Straits; Submarine banks; Surface water; Thermohaline structure and circulation. Turbulence and diffusion; Upwelling; Viscosity; Water; Water circulation; Water depth; North Atlantic; Strait of Gibraltar; Gulf of Cadiz; AN, North Atlantic; ANE, Norwegian Sea; ANE, North Atlantic, Subpolar Gyre; ANE, Atlantic, Iceland; AS, Central Atlantic; ANE, Atlantic, Mediterranean Water; ANW, Canada, Newfoundland and Labrador, Newfoundland; ASW, Equatorial Atlantic, Deep Western Boundary Current; ANW, North America, Grand Banks; AN, North Atlantic, North Atlantic Current; MED, Gibraltar Strait; Exchange flow; Water mass; General circulation models; Mixing process; Atlantic Ocean; salt-water intrusion; Entrainment(atmosphere, ocean); digital simulation; Mediterranean Sea; trajectory; ocean circulation; Ocean model
• ISSN: 0022-3670; 1520-0485
• DOI: 10.1175/JPO3020.1

Abstract The behavior of the Mediterranean Water in the North Atlantic Ocean sector of a global ocean general circulation model is explored, starting from its entry point at the Strait of Gibraltar. The analysis focuses primarily on one experiment in which explicit watermass exchange between the Mediterranean Sea and the Atlantic at the Strait of Gibraltar is permitted. The model produces an exchange rate of approximately 1 Sv (Sv ≡ 106 m3 s−1). This is comparable to estimates derived from field measurements. The density of the Mediterranean outflow, however, is lower than observed, mainly because of its high temperature (more than 2°C higher than in reality). The lower density of the outflow and the model’s inadequate representation of the entrainment mixing in the outflow region cause the Mediterranean Water to settle in a depth range ∼800–1000 m in the North Atlantic, about 200 m shallower than observed. Here an interesting current system forms in response to the intrusion of the Mediterranean Water, involving three main pathways. In the first, the Mediterranean Water heads roughly westward across the basin and joins the deep western boundary current. In the second, the water travels northward along the eastern boundary reaching as far as Iceland, where it turns westward to participate in the deep circulation of the subpolar gyre. In the third, the water initially moves westward to the central Atlantic just north of 30°N before turning northwestward to reach an upwelling region at the Grand Banks off Newfoundland. At this location, the saline Mediterranean Water is drawn upward to the ocean upper layer and entrained into the North Atlantic Current system flowing to the northeastern basin; part of the current system enters the Nordic seas.