Modelling Ice Nucleating Particles from High-Latitude Sources to Reproduce Arctic In Situ Concentrations

Ice nucleating particles (INPs) are crucial for the formation and evolution of ice-containing clouds, particularly in the Arctic, where INPs are scarce. Their influence on the radiative budget and its evolution in a warming climate remains an active area of research. INP sources in the Arctic are diverse, ranging from long-range transported mineral dust to local marine biological particles. However, their representation in regional and global models remains uncertain.

In this study, we implement emissions of marine primary organic aerosols (MPOAs) and high-latitude dust in the WRF-Chem chemistry-transport model. Using a set of offline ice nucleation schemes, we evaluate the contributions of different aerosol species to INP production. Model outputs are compared with in situ INP measurements from recent Arctic campaigns, assessing the performance of nucleation schemes in terms of particle concentrations.

Modeled MPOAs appear to be a major source of INP, but only because the model strongly overestimates organic aerosols. While certain nucleation schemes successfully reproduce baseline observed INP concentrations, they fail to capture the occasional sharp drops observed in freezing temperature. By incorporating Lagrangian dispersion modelling, we demonstrate that in-cloud removal of efficient INP along the likely transport pathways of INPs may account for the observed reductions in concentrations. Building on this insight, we implement, in WRF-Chem, new INP emission schemes sensitive to online nucleation processes during atmospheric transport. These updated tracers show improved agreement with in situ INP observations, offering new perspectives for more accurate representation of Arctic INPs in models.