Abstract

Brine rejection from sea ice provides a significant contribution to the buoyancy flux that drives ocean circulations.  Indeed, it provides the dominant contribution in the case of polynyas but the situation with consolidated sea ice is more complex.  Although salt is rejected completely by the ice crystals that form when the ocean freezes, it can be retained as saturated brine within the interstices of sea ice.  Buoyancy-driven convection driven in the interior of sea ice can cause the dense brine to drain into the underlying ocean via brine channels that form by dissolution of the ice matrix.  These intricate interactions between fluid flow and phase change occur on the scale of millimetres to centimetres within sea ice but their consequences must be captured within the sea-ice components of climate models.  I will describe the fundamental physical processes that govern the occurrence and rates of brine rejection from sea ice, and show how the understanding gained from detailed mathematical models of local, three-dimensional processes can be incorporated into an appropriately parameterised one-dimensional model of convection in sea ice suitable for inclusion in climate models.