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Johannes Leiner1,2, Dominik Schäuble 1,*, Philipp
Jeßberger1,2, Christiane Voigt1,2
1 Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen 2 Institut für Physik der Atmosphäre, Johannes Gutenberg Universität, Mainz *now at Institute for Advanced Sustainability Studies IASS, Potsdam, Germany The scavenging of gaseous nitric acid (HNO3) in clouds affects the partitioning of reactive nitrogen species in the troposphere and therefore has an impact on tropospheric ozone chemistry. Several studies investigate the uptake of nitric acid in different cloud types, still the underlying physical processes particularly in mixed phase clouds are not completely understood. During the ACRIDICON campaign at the Schneefernerhaus at the summit of Mt Zugspitze, cloud properties and trace gases including HNO3 were observed continuously over a 16 days period in September 2012. Gaseous HNO3 was detected with the Atmospheric chemical Ionization Mass Spectrometer AIMS. The instrument consists of a specially designed fast inlet system, a flow reactor, in which HNO3 molecules are ionized by SF5- ions via fluorid transfer and the quadrupole mass spectrometer detection unit. The AIMS instrument is calibrated daily during the campaign with a known of flux of HNO3 from a permeation oven to regularly check the instrument performance. During the campaign, several plumes containing up to 2 ppbv HNO3 were observed at the summit of Mt. Zugspitze. In two cases the decay in HNO3 plumes could have been caused by the scavenging of HNO3 in cloud particles. Future work will focus on these events. We will investigate the depletion in gas phase HNO3 and derive a scavenging coefficient from the analysis of gas phase HNO3 combined with information on aerosol composition, humidity and air parcel trajectories. |
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