An LES study of ice microphysical influences on roll cloud structure and dynamics off-ice flow

The marginal ice zone (MIZ), which is the transition region between the solid ice pack and open ocean, is an area in which very strong interactions take place between the atmosphere, sea-ice, and ocean. During periods of off-ice flow, exceedingly cold polar air comes into contact with the relatively warm ocean producing copious convection, cloud cover, snow precipitation, roll convection, and strong surface winds. Our recent modeling studies are showing that ice microphysical processes have a strong effect on the evolution of the boundary layer (BL) during off-ice flow events.

In this study, we present simulations of roll cloud formation over the MIZ using a large-eddy simulation model coupled to a detailed microphysical scheme. Simulations have been conducted with a dry BL , non-precipitating liquid-phase cloud-topped BL, and a mixed-phase cloud-topped BL. The influence of ice-phase microphysical processes on roll cloud stucture and dynamics is discussed along with the possible influence of microphysical processes on the surface stresses.