A physically based brine flux parameterization for sea ice

The drainage of brine from sea ice impacts climate dynamics both by providing buoyancy forcing for the polar oceans and by influencing sea-ice material properties that influence ice growth and decay. Hence, a physically based description of brine drainage is desirable for use in sea-ice models. We evaluate several previous parameterizations in light of experimental data for growth of young ice and scaling laws deduced from mushy layer theory. Physical and numerical limitations are highlighted, and it is shown that previous parameterizations do not capture the change in brine flux under varying growth conditions. By comparison, a scaling law deduced from mushy layer theory respects the underlying conservation laws and provides an improved prediction of brine fluxes. This suggests that the mushy layer formalism would provide a strong basis for development of new models to predict vertical salinity profiles and reduce the need for ad-hoc assumptions about the form of brine drainage.