An investigation of the general circulation of the Arctic Ocean using an isopycnal model

A numerical simulation of the general circulation of the Arctic Ocean is presented using Oberhuber’s (1993a) coupled sea ice, mixed layer, isopycnal general circulation model (OPYC). The model’s novel feature is that the ocean component uses density surfaces as the vertical coordinate. The model domain includes the Arctic Ocean, the Greenland-Iceland-Norwegian (GIN) Sea, and the North Atlantic Ocean. The horizontal resolution is 1.0° in a spherical coordinate system that is rotated with respect to geographical coordinates. The vertical is resolved into eleven isopycnal layers of which the uppermost layer is a turbulent mixed layer. The sea ice is modelled using the dynamic-thermodynamic model of Oberhuber which incorporates the Hibler viscous-plastic rheology. A restriction of the coupled model used here is the artificial placement of solid walls across the Bering Strait and at the equator in the Atlantic Ocean. Monthly climatological atmospheric forcing is used to spin the model into a cyclo-stationary equilibrium. Model results are presented and discussed with respect to observational and previous modelling studies. The simulated water mass properties and circulation are in reasonable agreement with observations. Based on the simulation results, new circulation patterns are suggested for the deep flow within the Arctic Ocean. In particular, it is proposed that for the Atlantic layer and deeper waters there exists a multi-gyre circulation pattern consisting of cyclonic gyres that essentially follow contours of bottom topography.