Numerical Representations of Marine Ice-Nucleating Particles in Remote Marine Environments Evaluated Against Observations

The abundance and sources of ice-nucleating particles, particles required for heterogeneous ice nucleation, are long-standing sources of uncertainty in quantifying aerosol-cloud interactions. In this study, we demonstrate near closure between immersion freezing ice-nucleating particle number concentration (n_INPs) observations and n_INPs calculated from simulated sea spray aerosol and dust. The Community Atmospheric Model with constrained meteorology was used to simulate aerosol concentrations at the Mace Head Research Station (North Atlantic) and over the Southern Ocean to the south of Tasmania (Clouds, Aerosols, Precipitation, Radiation, and atmospherIc Composition Over the southeRN ocean campaign). Model-predicted n_INPs were within a factor of 10 of n_INPs observed with an off-line ice spectrometer at Mace Head Research Station and Clouds, Aerosols, Precipitation, Radiation, and atmospherIc Composition Over the southeRN ocean campaign, for 93% and 69% of observations, respectively. Simulated vertical profiles of n_INPs reveal that transported dust may be critical to n_INPs in remote regions and that sea spray aerosol may be the dominate contributor to primary ice nucleation in Southern Ocean low-level mixed-phase clouds.