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

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Guy, Heather, Brooks, Ian M., Carslaw, Ken S., Murray, Benjamin J., Walden, Von P., Shupe, Matthew D., Pettersen, Claire, Turner, David D., Cox, Christopher J., Neff, William D., Bennartz, Ralf, Neely III, Ryan R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: article; Verlagsveröffentlichung; East Greenland; Greenland; Ice Sheet
• Online Access: https://doi.org/10.5194/acp-21-15351-2021; https://noa.gwlb.de/receive/cop_mods_00058408; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00058051/acp-21-15351-2021.pdf; https://acp.copernicus.org/articles/21/15351/2021/acp-21-15351-2021.pdf

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