Small scale processes in sea ice modeling
Description
A numerical simulation is used to predict the time evolution of the solidification of sea ice, as well as the internal channel distribution and solute rejection rate resulting from a top-chilled scenario. This situation is commonly found in nature due to the freezing of seawater over large areas of the globe. Similar processes occur during the solidification of magma bodies inside the Earth. Examples in industry include the solidification of alloys, crystal growth, and freezing of food products. In this research the formation of sea ice is specifically addressed, where the presence and distribution of brine drainage channels are expected to have an influence on ice cover variations and on the ocean salinity distribution, both factors in the climate equation A 2-D continuum model is used which describes the momentum, heat, and species transport in a NaCl-H2O binary system. As the sea ice grows, it forms as slush where both liquid and solid phases coexist, similar to porous media. Brine is rejected from the interior of this mushy zone and removed at the interface through both diffusion and convection. Results of several simulations illustrate the expected preferential channel-type flow of the heavy brine. Growth rates of sea ice and rejection rates of brine are calculated and compare favorably with experimental data. Additionally, scaling analyses of the momentum and energy equations yield simple parameterizations that are suitable for inclusion in general circulation models of the ocean