Controls on surface aerosol particle number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet

Abstract. This study presents the first full annual cycle (2019–2020) of ambient surface aerosol particle number concentration measurements (condensation nuclei > 20 nm, N20) collected at Summit Station (Summit), in centre Greenland Ice Sheet (72.58∘ N, −38.45∘ E; 3250 ma.s.l.). The mean 2019 was 129 cm−3, with 6 h ranging between 1 and 1441 cm−3. highest monthly concentrations occurred during late spring summer, minimum occurring February (mean: 18 cm−3). High-N20 events are linked to anomalous anticyclonic circulation over descent free-tropospheric down surface, whereas low-N20 cyclonic south-east that drives upslope flow enhances precipitation en route Summit. Fog strongly affects concentrations, on average reducing N20 by % 3 fog formation. Extremely-low-N20 (< 10 cm−3) occur all seasons, we suggest fog, potentially cloud formation, can be limited low central Greenland.