A Diagnostic Study of the Northern Atlantic Subpolar Gyre

Abstract

Abstract A three-layer vorticity diagnostic calculation is made for an area of the northern North Atlantic centered at 55°N, 22.5°W. It suggests the circulation there is not driven by vertical Ekman suction due to the wind stress, but due to nearly horizontal due nearly the sloping mean density surface in that portion of the upper ocean mixed by deep wintertime convection. The computed act annual heat gain is −44 ± 8 W m−2. Such diagnostics define a linear relation between buoyancy gain and Ekman pumping and hence serve as a link; through the ocean, between meteorologist's charts of wind stress and heat gain. The meridional transport is strongly influenced by bottom topography; the upward slope of the bottom toward the north permits a large net northward transport.