Ice Nucleation in Arctic Cloud

Low altitude clouds are intricately linked to the Arctic’s climate and uncertainty in their interaction with aerosol means there is substantial uncertainty in projections of Arctic climate. These clouds are below 0 Degree Celsius and are therefore susceptible to the formation of ice which can dramatically alter their radiative properties, yet our knowledge of the ice nucleating particle population in the high Arctic is extremely limited. The summertime high Arctic is generally considered to be pristine, with minimal transport from mid- to low-latitudes resulting in very low aerosol concentrations. Hence, there has been a great deal of discussion of the source of ice nucleating particles relevant for these clouds.  In this presentation I will talk about the INP measurements made during the MOCCHA cruise to the North Pole in summer 2018 on the Oden ice breaker (made by Grace Porter and Mike Adams, in collaboration with the MOCCHA team).  The initial results show that INPs at the North Pole are extremely variable, with the highest concentrations most likely corresponding to a source outside of the pack ice. I will then talk about the potential sources of these ice nucleating particles, before speculating what this might mean for a future Arctic.