The Influence of Ice Crystal Habit on Arctic Cloud Lifetime: Radiative Implications

During the Arctic cold season, clouds containing mixes of liquid and ice are prevalent over the sea-ice and ocean. These clouds exist in extensive decks and are relatively long-lived. Furthermore, because these clouds contain substantial amounts of supercooled liquid, they have a large impact on the radiative budget of the sea-ice. Prior studies have shown that these clouds are relatively sensitive to perturbations in the concentrations of ice nucleating aerosol: Small increases in the numbers of ice nucleating aerosol particles can lead to rapid glaciation of the supercooled liquid leading to dissipation of the cloud layer. However, these results depend critically on how rapid vapor is taken up by the ice crystals. We will show results indicating that predicting ice crystal habits, which currently isn't done in numerical models, may be critical for capturing the partitioning of cloud mass between the liquid and ice phases. Because the surface radiative budget is very sensitive to the liquid cloud fraction, we discuss the implications of predicting ice habit for estimating the surface radiative energy balance.