East Antarctic seasonal sea-ice and ocean stability: a model study

Abstract

A high-resolution primitive equation ocean model has been coupled to a dynamic/thermodynamic sea-ice model and applied to a region of the Southern Ocean south of Australia. The model is found to be very sensitive to the surface fresh-water flux! A stable seasonal cycle of sea-ice advance and retreat is simulated only for sufficient surface fresh-water fluxes. For fresh-water fluxes below a threshold value of around 40 cm a−1 the coupled system enters a thermal mode characterised by vertical homogeneity of the oceanic temperature and salinity fields. Such an ocean has a surface temperature that is too warm for a sea-ice cover to develop. Spatial and temporal variability of the oceanic heat llux into the upper model layer iS examined for the stable simulations. High values of this oceanic heat flux (~40Wm−2) occur during the sea-ice formation period (March-June), with values as low as 5 wM−2 occurring in November. The source of this heat is primarily convective, a process induced by brine rejection during ice growth.