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UP: Fachverband Umweltphysik

UP 2: Clouds and Aerosols

UP 2.4: Invited Talk

Thursday, September 2, 2021, 14:50–15:10, H3

Nucleation and growth of atmospheric aerosol particles: Recent results from CLOUD at CERN — •Joachim Curtius — Institut für Atmosphäre und Umwelt, Goethe Universität Frankfurt, Frankfurt am Main, Germany

Atmospheric aerosol particles influence cloud formation, climate and human health. A large fraction of the atmospheric aerosol forms by nucleation from the gas phase. In order to understand and predict atmospheric new particle formation it is of importance to perform experiments under well-controlled laboratory conditions to investigate the details of the formation of molecular clusters. By performing more than 2200 individual experiments over the past decade, the CLOUD project at CERN has studied the most relevant chemical systems for a large range of atmospheric conditions at unprecedented precision. It allows the direct and simultaneous measurement of all relevant variables at atmospheric conditions. The physico-chemical mechanisms (e.g. ion-induced vs. neutral path) for the formation and initial growth of molecular clusters are determined. For example, the nitric acid-sulfuric acid-ammonia system has been studied recently that is predicted to cause nucleation in such diverse conditions as East Asian megacities in winter or in the upper troposphere above the Indian monsoon. Overall, a greatly improved understanding has been reached for the role of new particle formation in the atmosphere and for characterizing the various factors that act as boosters or inhibitors for the nucleation and growth processes. An overview of the current understanding, including its role for cloud formation and climate is given.