The parameterisation of Mediterranean–Atlantic water exchange in the Hadley Centre model HadCM3, and its effect on modelled North Atlantic climate.

Ivanovic, Ruza F., Valdes, Paul J., Flecker, Rachel, Gregoire, Lauren J. and Gutjahr, Marcus (2013) The parameterisation of Mediterranean–Atlantic water exchange in the Hadley Centre model HadCM3, and its effect on modelled North Atlantic climate. Ocean Modelling, 62 . pp. 11-16. DOI 10.1016/j.ocemod.2012.11.002.

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Abstract

Multiple palaeo-proxy and modelling studies suggest that Mediterranean Outflow Water (MOW) is an important driver of Atlantic Meridional Overturning Circulation (AMOC), particularly during periods of weak overturning. Here, we employ the HadCM3 ocean–atmosphere General Circulation Model (GCM) to investigate the effect of using different parameterisations of Mediterranean–Atlantic water exchange on global ocean circulation and climate. In HadCM3, simulating flow through the Gibraltar Straits with an ‘open seaway’ rather than a ‘diffusive pipe’ causes a shoaling and strengthening of the MOW plume. This reorganises shallow Atlantic circulation, producing regional surface air temperature anomalies of up to + 11 °C and −7.5 °C. We conclude that when investigating the influence of MOW on modelled ocean circulation and climate, an accurate parameterisation of Mediterranean–Atlantic exchange is important and should match observed fresh water and salinity flux constraints. This probably cannot be achieved through a simple ‘diffusive pipe’ with depth invariant mixing coefficient.

Document Type: Article
Keywords: Marine gateway; Gibraltar Straits; Mediterranean outflow; North Atlantic circulation; Atlantic Meridional Overturning Circulation
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.ocemod.2012.11.002
ISSN: 1463-5003
Date Deposited: 14 May 2013 10:21
Last Modified: 06 Feb 2017 12:36
URI: http://oceanrep.geomar.de/id/eprint/21232

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