Seasonal Arctic sea-ice simulations with a prognostic ice-ocean model
A prognostic ice-ocean model of the Arctic, Greenland and Norwegian seas with daily wind and atmospheric forcing is integrated for 30 years to quasi-equilibrium. Three simulations are carried out to investigate the role played by ice deformation and transport in baroclinic adjustment of the Arctic Ocean: a standard run with precipitation and ice transport, a simulation without precipitation and a “thermodynamics only” simulation without ice transport but including precipitation. A diagnostic model is integrated for five years to serve as a comparative control run. Comparison of the vertically integrated stream-function of each of the model runs indicates that the vertical density stratification needed to maintain the circulation of the Arctic Ocean is reduced excessively when precipitation is neglected and artificially enhanced if ice transport out of the basin is ignored. This effect is even more noticeable in the surface currents and is also apparent in a comparison of simulated and observed drifting-buoy tracks. An analysis of the salt budget of the Arctic Ocean indicates that the three main components, salt transport by the ocean, salt flux from the annual cycle of ice, and a fresh-water flux from precipitation and river runoff are approximately of the same magnitude. The main circulation deficiency identified in the simulations is an inadequate flow of Atlantic water into the Arctic Basin through the Fram Strait.