Pratap, VikramHennigan, ChristopherStieger, BastianTilgner, AndreasPoulain, Laurentvan Pinxteren, DominikSpindler, GeraldHerrmann, Hartmut2025-04-012025-04-012025-02-10Pratap, V., Hennigan, C. J., Stieger, B., Tilgner, A., Poulain, L., van Pinxteren, D., Spindler, G., and Herrmann, H.: Climatology of aerosol pH and its controlling factors at the Melpitz continental background site in central Europe, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2025-457, 2025.https://doi.org/10.5194/egusphere-2025-457http://hdl.handle.net/11603/37872Aerosol acidity has importance for the chemical and physical properties of atmospheric aerosol particles and for many processes that affect their transformations and fate. Here, we characterize trends in aerosol pH and its controlling factors over the period of 2010 – 2019 at the Melpitz research station in eastern Germany, a continental background site in central Europe. Aerosol liquid water content (ALWC) decreased by 50 % during the analyzed time period in response to decreasing sulfate and nitrate. Aerosol pH exhibited an increase of 0.06 units per year, a trend that was distinct from other regions. Seasonal analysis showed strong variability in factors controlling aerosol pH.36 pagesen-USAttribution 4.0 Internationalhttps://creativecommons.org/licenses/by/4.0/Text