Abstract:

Although low-level mixed phase clouds are ubiquitous in both the Arctic and Antarctic, large scale models have historically struggled to simulate them, leading to uncertainties or errors in the simulated surface energy budget, precipitation, and even equilibrium climate sensitivity. Polar low clouds are sensitive to changes in aerosol and insufficient representation of aerosol-cloud interactions in models is a major contributor to these uncertainties. This presentation will focus on a subset of aerosols known as ice nucleating particles (INPs), which are required for the initiation of ice in mixed phase clouds and can have an outsized effect on cloud phase and related climate feedbacks due to their relative scarcity. Substantially more glaciation is observed in Arctic mixed phase clouds than those over the Southern Ocean, which is thought to be due to differences in the number and composition of available INPs. I will first discuss recent in situ measurements of INPs over the Southern Ocean, including potential sources and possible changes in a warming climate. The second half of the presentation will focus on Arctic aerosol-cloud interactions, particularly efforts to improve model representation of mineral dust, a highly efficient INP, in the region.