Abstract

The growth of frazil ice is an important mode of ice formation in the cryosphere. We consider models of a population of ice crystals with different sizes to provide insight into the treatment of frazil ice in large-scale models. We apply our model to a simple mixed layer (such as at the surface of the ocean) and to a buoyant plume under a floating ice shelf. We provide numerical calculations and scaling arguments to predict the occurrence of frazil-ice explosions (periods of rapid ice growth). Faster crystal growth rate, higher secondary nucleation and slower gravitational removal make frazil-ice explosions more likely. We identify steady-state crystal size distributions, which are largely insensitive to crystal growth rate but are affected by the relative importance of secondary nucleation to gravitational removal. Finally, we show that the fate of plumes underneath ice shelves is dramatically affected by frazil-ice dynamics. Differences in the parameterization of crystal growth and nucleation give rise to radically different predictions of basal accretion and plume dynamics; and can even impact whether a plume reaches the end of the ice shelf or intrudes at depth.

Further details can be found at www.the-cryosphere-discuss.net/tc-2017-155/ (Rees Jones, D. W. and Wells, A. J.).