On the Role of Eddies and Surface Forcing in the Heat Transport and Overturning Circulation in Marginal Seas

• Published in: Journal of climate Vol. 24; no. 18; pp. 4844 - 4858
• Main Author: Spall, Michael A.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 15.09.2011
• Subjects: Atmosphere; Atmospheric circulation; Atmospheric cooling; Atmospheric models; Buoyancy; Circulation; Climate models; Density; Dimensionless numbers; Earth, ocean, space; Eddies; Eddy heat flux; Exact sciences and technology; Exchanging; Exports; External geophysics; General circulation models; Heat; Heat flux; Heat loss; Heat transfer; Heat transport; Marginal seas; Marine; Meridional heat transport; Meridional overturning circulation; Mesoscale eddies; Modelling; Ocean circulation; Ocean circulation models; Ocean currents; Ocean models; Oceanography; Oceans; Primitive equations; Scaling; Sea transportation; Sea water; Seas; Theory; Thermohaline circulation; Topography; Water circulation; Water temperature; Wind; Wind effects; Arctic Ocean; Greenland Sea; North Atlantic; Norwegian Sea; Atlantic Ocean; Nordic Seas; AN, North Atlantic; ANE, Norwegian Sea; Atmosphere model; Primitive equation; Heat loss; Wind effect; Climate models; Subpolar zone; buoyancy; Ocean model; Mesoscale; winds; thermohaline circulation; cooling; Iceland sea; Forcing; marginal seas; Vortex; heat transfer; ocean circulation; high resolution
• DOI: 10.1175/2011jcli4130.1
• ISSN: 0894-8755

The factors that determine the heat transport and overturning circulation in marginal seas subject to wind forcing and heat loss to the atmosphere are explored using a combination of a high-resolution ocean circulation model and a simple conceptual model. The study is motivated by the exchange between the subpolar North Atlantic Ocean and the Nordic Seas, a region that is of central importance to the oceanic thermohaline circulation. It is shown that mesoscale eddies formed in the marginal sea play a major role in determining the mean meridional heat transport and meridional overturning circulation across the sill. The balance between the oceanic eddy heat flux and atmospheric cooling, as characterized by a nondimensional number, is shown to be the primary factor in determining the properties of the exchange. Results from a series of eddy-resolving primitive equation model calculations for the meridional heat transport, overturning circulation, density of convective waters, and density of exported waters compare well with predictions from the conceptual model over a wide range of parameter space. Scaling and model results indicate that wind effects are small and the mean exchange is primarily buoyancy forced. These results imply that one must accurately resolve or parameterize eddy fluxes in order to properly represent the mean exchange between the North Atlantic and the Nordic Seas, and thus between the Nordic Seas and the atmosphere, in climate models.