Characterizing Arctic Aerosol Properties for Evaluation of Aerosol-Cloud Interactions on the North Slope of Alaska

Aerosols that serve as cloud condensation nuclei (CCN) and ice nucleating particles (INPs) have the potential to modulate cloud microphysical properties. In regions such as the Arctic, aerosol-cloud interactions are severely understudied yet have significant implications for surface radiation. Further, uncertainties in model representations of heterogeneous nucleation are a significant hindrance to simulating Arctic mixed-phase cloud processes. Characterizing aerosol chemical, physical, and cloud nucleating properties is pertinent to evaluating of the role of aerosols in altering Arctic cloud microphysics, lifetime and radiative forcing. We present an analysis of in situ observations of a wide range of aerosol properties on the North Slope of Alaska. Airborne measurements of aerosol and cloud properties from the U.S. Department of Energy’s Atmospheric Radiation Measurement Airborne Carbon Measurements (ARM-ACME-V) campaign during the summer of 2015 provide valuable insight into the vertical and spatial heterogeneity of aerosols and their potential to influence cloud formation over the North Slope, which is controlled by both long-range transported and regional sources. We compare these observations to previous airborne field campaign measurements to delineate the diversity in the vertical distribution of aerosols over several time periods. Ground-based observations are utilized to support ARM-ACME-V airborne measurements and to evaluate the sources of aerosol in the boundary layer as compared to the free troposphere. Ultimately, this detailed information is used to inform the parameterization of CCN and INPs in large-eddy simulations to evaluate the sensitivity of cloud radiative forcing to different aerosol conditions. The goal is to improve process understanding of aerosol-cloud interactions in Arctic mixed-phase clouds and their subsequent impacts on the surface energy budget.