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. This is altering the sources and sinks of aerosols, which influence the regional radiation balance and cloud formation. However, direct observations of turbulent particle fluxes over sea ice are scarce, limiting our understanding of the processes that control the exchange of aerosols between the surface and the atmosphere. 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 particle sources and sinks over closed ice, leads, and open water. Overall, net particle deposition dominated, with median deposition fluxes of −0.02 (interquartile range −0.10 to 0.04) × 10 6  m −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 0.98×10 6  m −2  s −1 (95 % confidence interval excluding zero) 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 and may help to reduce related uncertainties in Arctic aerosol and climate model simulations.