Turbulent atmospheric particle fluxes in the High Arctic: surface type dependence and variability

Abstract. The Arctic is warming at a significantly faster rate than the global average, which is affecting local climate processes. Aerosol particles play a central role by influencing the energy balance directly through the scattering and absorption of solar radiation and indirectly by acting as cloud condensation nuclei. However, the processes that control aerosol concentrations, such as the mechanisms governing vertical particle exchange, are not well understood, particularly over sea ice. During the ARTofMELT campaign in spring 2023, five weeks of continuous eddy covariance measurements of turbulent particle fluxes were conducted in the High Arctic to investigate the spatial and temporal variability of particle sources and sinks over three surface types. Overall, net particle deposition dominated, with median deposition fluxes of −0.02 × 106m-2 s-1 over closed ice. This confirms the role of ice surfaces as a particle sink under low to moderate turbulence. Under strong winds, net particle emission fluxes of up to 0.98 × 106m-2 s-1 were observed over closed ice surfaces, which are likely linked to processes involving blowing snow. A mixture of emission and deposition was observed over leads and open water surfaces. These observations highlight how surface heterogeneity and turbulence intensity can influence particle exchange in the High Arctic. As sea ice retreats and the extent of open water increases, local particle sources are expected to become more relevant to Arctic aerosol budgets and cloud processes. The results provide observational constraints on particle fluxes, helping to reduce related uncertainties in Arctic model simulations.