Atmospheric Sciences Division Seminar

There is a significant warming in the Arctic that is evident in both observations and in the future climate predictions. The Arctic warming is greater than any other region, however, the degree of warming is inconsistent among the climate models even for the same emission scenarios. Clouds, especially low-level clouds, are a prevailing feature of the Arctic atmosphere. They strongly affect the surface radiative and energy budget, which makes them a key component of the Arctic climate. Recent inter-comparison studies using regional climate models show that models are incapable of reproducing the supercooled liquid water observed in clouds during the cold season. Large discrepancies exist in the partitioning of phase between ice and liquid water among different models. It is currently thought that these discrepancies are due to the uncertainties in ice nuclei concentrations, ice nucleation, and ice crystal habits used in models. Predicting these physical processes controls the partitioning between liquid water and ice, and hence the impact of mixed-phase clouds on the surface energy budget. There is a need to improve model cloud predictions in the Arctic, however, the microphysical uncertainties mentioned above are tied directly to the cloud dynamics that help maintain persistent mixed-phase clouds. Therefore, this study analyzes and inter-compares the impacts of different ice nuclei concentrations, ice nucleation mechanisms and ice crystal habits on mixed-phase cloud dynamics.