Numerical modelling of oceanic circulation and sea ice in the North Atlantic–Arctic Ocean–Bering Sea region

Abstract

We give the physical statement and numerical algorithms of an original model of oceanic circulation based on splitting over physical processes and geometric coordinates. Splitting makes it possible to effectively realize implicit time integration schemes for transport-diffusion equations. The model uses a vertical σ coordinate. We specify 27 vertical levels with higher resolution in the upper layer and use horizontal resolution 1/3° in latitude and 1/3° in longitude. We model the North Atlantics from 20° S coupled with the Arctic Ocean. The model is written in a rotated spherical coordinate system with its poles beyond the integration domain.We carried out an experiment simulating the climatic annual cycle of oceanic fields characteristics for 12 years taking into account the melting, growth, and drift of oceanic ice. The boundary conditions are given by the OMIP project database. Instead of the stream function we use a sea level function in the model. We compare the model current fields, sea level fields, mass and heat transport through the main straits both with observed data and other authors' simulation results. The model realistically reproduces all large-scale currents and features of the sea level field. The mass transport 5 Sv of the dense saline bottom water from the Greenland Sea to the Atlantic was calculated for the Denmark Strait. We revealed a circulation compensation mechanism for differently directed mass and heat flows in the Atlantic–Arctic exchange processes.