A coupled ice-ocean model is employed to examine roles of ocean circulation on sea ice formation and distribution along the east coasts of North America and Greenland. The model has a flat bottom and a rectangular domain with a coastal boundary to the west, an artificial solid boundary to the north, and open eastern and southern boundaries. The model is driven by idealized alongshore wind stress and atmospheric cooling; with a maximum amplitude at the middle. The open water heat flux is locally specified with both seaward and southward decay, and the heat flux through ice is taken to be inversely proportional to the ice thickness. Ice internal stresses are simplified under the assumption that the major strain is cross-shore shear deformation. The ocean model has three levels: the surface mixed layer and two levels in the lower ocean. Linear momentum equations are used, and a geostrophic cross-shore momentum balance is assumed. vertical viscosity is represented only by the surface and bottom Ekman flow. Equations for temperature and salinity retain advection and diffusion terms in both vertical and horizontal directions. The model reveals the following important roles of the ocean: northerly wind induces shoreward Edman flow and southward barotropic flow, which develops only to the southern (downstream in the sense of long coastal-trapped wave propagation) side of wind forcing region and merges westward owing to the β-effect. Coastal downwelling produces additional baroclinic alongshore flow, intensifying (weakening) the southward flow in the upper (lower) ocean.

Cyclonic circulation is generated by differences in Ekman flow between the ice-covered onshore area and open-water offshore area. Ice, which occupies the coastal area, is narrowed dynamically by the shoreward Ekman flow and thermodynamically by the warm offshore water in the Ekman flow. Ice is also advected southward by the alongshore current, associated with the coastal flow and the cyclonic circulation, as well as direct wind stress. When a lower ocean is warmer than the freezing point, convective overturning carries heat upward and reduces ice formation. Ice grows faster over downwelled and southward advected cold anomalies in the lower ocean. ¿ American Geophysical Union 1988