1,2,1,11,2,3,5,6,6,8,9,10,2,4,1- 1École Polytechnique Fédérale de Lausanne, Civil and Environmental Engineering, Extreme Environments Research Laboratory , Switzerland (berkay.donmez@epfl.ch)
- 2Laboratory of Atmospheric Processes and their Impacts (LAPI), School of Architecture, Civil & Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- 3Environmental Remote Sensing Laboratory, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
- 4Center for the Study of Air Quality and Climate Change (CSTACC), Institute of Chemical Engineering Sciences, Foundation for Research & Technology-Hellas (FORTH), Patras, Greece
- 5Institute for Meteorology, Universität Leipzig, Leipzig, Germany
- 6Atmospheric Composition Unit, Finnish Meteorological Institute, Helsinki, Finland
- 7Environment and Climate Change Canada
- 8Bolin Centre for Climate Research, Sweden
- 9Department of Environmental Science, Aarhus University
- 10Leibniz Institute for Tropospheric Research, Germany
- 11now at School of Earth and Atmospheric Sciences,Queensland University of Technology (QUT), Australia
- 12now at Univ. Grenoble Alpes, CNRS, INRAE, IRD, Grenoble INP, IGE, 38000, Grenoble, France
Recent studies show that warm and moist air intrusions are major sources of aerosol particles in the Arctic, affecting local radiative impacts by supplying Cloud Condensation Nuclei (CCN). However, their influence on aerosol size modes, CCN, and cloud droplet number concentrations remains poorly constrained. Here, we use long-term aerosol observations from five Arctic observatories to quantify intrusion impacts. We find that intrusions strongly perturb Arctic CCN, especially in summer, when accumulation-mode and CCN concentrations increase markedly at all sites. In winter and spring, two regimes emerge: intrusions reduce number concentrations at sites near 0° longitude (Zeppelin, Villum, Alert) but enhance them near 180° (Tiksi, Utqiaġvik/Barrow), consistent with competing effects of pollution sources and wet scavenging along trajectories. Intrusions also systematically modify cloud droplet number concentration (Nd): Nd increases at all sites in summer, while in winter it increases at Tiksi and Utqiaġvik/Barrow but decreases at Zeppelin, Villum, and Alert. Overall, intrusions are a key regulator of Arctic aerosol and cloud properties and an important component of the evolving Arctic climate system.
Beyond aerosol–cloud number effects, it is unclear how intrusion events modulate cloud optical depth, liquid water content, and precipitation across Arctic sites and seasons. To address this, we will combine cloud and precipitation observations from the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition with reanalysis data to quantify systematic intrusion-driven changes in liquid water content and precipitation occurrence. Finally, we will use the non-hydrostatic mesoscale Weather Research and Forecasting (WRF) model to examine the sensitivity of mixed-phase cloud lifetime and associated precipitation to intrusion occurrence, providing process-level constraints on how intrusions shape Arctic mixed-phase cloud persistence and hydrometeor production.
How to cite: Dönmez, B., Boyd Pernov, J., Foskinis, R., Calmer, R., Georgakaki, P., Angot, H., Asmi, E., Backman, J., Chan, T., Krejci, R., Massling, A., Skov, H., Tunved, P., Wiedensohler, A., Weinhold, K., Nenes, A., and Schmale, J.: Warm–Moist Intrusions as a Key Regulator of Arctic Aerosols, Clouds, and Precipitation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18175, https://doi.org/10.5194/egusphere-egu26-18175, 2026.
