The wind-driven circulation of ice and water in a polar ocean

Abstract

A steady-state theory for the circulation of a wind-driven, baroclinic, ice-covered ocean is presented. The ice is considered to flow under the action of five forces: the air stress, the water stress, the stress transmitted through the ice pack, the Coriolis force, and the pressure gradient force due to the tilting of the sea surface. Prandtl-type boundary layers are assumed at both ice surfaces. The ice is treated as a film of highly viscous fluid, composed of ice floes which act as fluid elements having rigid upper and lower surfaces characterized by roughness parameters. The theory is applied to the Arctic Ocean, where the β-plane approximation cannot be made, so the actual variation of the Coriolis parameter with latitude is considered. A nonanalytical stress field deduced from the field of mean sea-level pressure is used for the numerical integration of the equations. The solutions for the ice circulation show an anticyclonic cell centered in the Beaufort Sea with a broad stream running from the Asian coast across the pole to Greenland. All solutions show an anticyclonic gyral in the surface waters on the Pacific side of the ocean, and it is theorized that an ice eddy viscosity as high as 3.0×1012 cm2 sec−1 is necessary in order for the gyral to occupy its observed position.