Evaluation of ice nucleating particles and their sources in the central Arctic during the Multidisciplinary drifting Observatory for Study of Arctic Climate (MOSAiC) experiment

The accelerated rate of warming in the Arctic is of great concern due to potential impacts that include release of greenhouse gases from permafrost, melting glacial ice contributing to sea level rise, and declining sea ice cover exposing the darker ocean surface. Clouds play a crucial role in regulating the energy reaching the sea ice and snow surfaces, but the magnitude of their effects on surface temperature is not well constrained in the Arctic, in part due to limited information on aerosols that serve as seeds for cloud particle formation. Specifically, aerosols that serve as ice nucleating particles (INPs) are vastly understudied, especially above the central Arctic Ocean. To date, a full year's worth of INP measurements have not been conducted anywhere in the Arctic and no INP data exist from the central Arctic in the winter or spring, creating a significant gap in understanding Arctic mixed-phase cloud (AMPC) microphysical processes. The year-long transpolar drift experiment, Multidisciplinary drifting Observatory for Study of Arctic Climate (MOSAiC), provided the opportunity to execute these novel INP measurements. Here, we present preliminary INP results from MOSAiC from a wide range of total and size-resolved aerosol, seawater, sea ice core, and snow samples. Unique cases are presented, including the significant transition in the INP populations during winter storms and during the exposure of open water such as leads and melt ponds. The overarching goal of this work is to achieve unprecedented characterization of INP abundance and sources (including biological) to evaluate their capacity to modulate cloud ice formation over the central Arctic spanning a full sea ice cycle.