A salt flux model for salinity change through ice production in the Greenland Sea, and its relationship to winter convection

A salt flux model which incorporates ice formation, advection and melt, as well as time-dependent brine drainage from frazil-pancake ice, has been developed for the central Greenland Sea in winter. Information from ice drifting buoys suggests that this region can be thought of as similar to a latent heat polynya, with the wind blowing newly formed sea-ice constantly in a southerly or southeasterly direction such that it melts in a different area from that of its formation. The result is a salt refinement process generating a net positive salt flux over the ice formation region, which may play an important role in stimulating deep open-ocean convection. By combining buoy data, ECMWF meteorological data and passive microwave ice concentration data the model is used to estimate the sea ice-derived salt flux over the 1996-1997 winter. Salt fluxes of over 40 kg m(-2) were obtained in the center of the region, which corresponds closely an area where a maximum depth of convection is seen in winter cruises. The model gives realistic results when compared with in situ ice and oceanographic data gathered in the region, and suggests that ice formation and drift play an important role in the preconditioning of surface waters for deep water formation events.