A Simple Steady-State Coupled Ice-Ocean Model, with Application to the Greenland-Norwegian Sea

Abstract

A thermodynamic reduced-gravity ocean model forced by the steady-state surface wind stress and a Haney-type heat flux was used to determine the climatological ice-edge position, ice thickness, ocean circulation, and upper-ocean temperature in a high-latitude meridional channel. The ice model used is purely thermodynamic; however, a parameterization is used to allow the surface wind stress to be transmitted to the water below the ice. The temperature distribution of the upper ocean is specified along the southern zonal boundary of the model domain, and the heat equation is integrated from this boundary poleward along streamlines for the mass transport. As a column of warm water moves poleward, its temperature tends to decrease since the air temperature monotonically decreases to the north. At high latitudes the steady-state heat balance between horizontal advection and cooling to the atmosphere can no longer hold in an ice-free ocean. Thus, an ice layer forms to insulate the ocean from the very cold air temperatures at these latitudes. The model is applied to the Greenland and Norwegian Seas, between 60° and 80°N, and between the east coast of Greenland and 15°E. Exterior to a narrow western boundary layer, the predicted ice-edge position compares favorably with the climatological 90% ice concentration isoline obtained from an analysis of 32 years of Arctic sea ice data.