Denitrification by large NAT particles: the impact of reduced settling velocities and hints on particle characteristics

• Published in: Atmospheric Chemistry and Physics
• Main Authors: Woiwode, W., Grooss, J.-U., Oelhaf, H., Molleker, S., Borrmann, S., Ebersoldt, A., Frey, W., Gulde, T., Khaykin, Sergey, Maucher, G., Piesch, C., Orphal, J.
• Other Authors: Institute for Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology = Karlsruher Institut für Technologie (KIT), Institut für Energie- und Klimaforschung - Stratosphäre (IEK-7), Forschungszentrum Jülich GmbH, Helmholtz-Gemeinschaft = Helmholtz Association-Helmholtz-Gemeinschaft = Helmholtz Association, Max-Planck-Institut für Chemie (MPIC), Max-Planck-Gesellschaft, Institute for Data Processing and Electronics (IPE), School of Earth Sciences Melbourne, Faculty of Science Melbourne, University of Melbourne-University of Melbourne, Central Aerological Observatory (CAO), Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), STRATO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; Arctic
• Online Access: https://hal.science/hal-00956379; https://hal.science/hal-00956379/document; https://hal.science/hal-00956379/file/acp-14-11525-2014.pdf; https://doi.org/10.5194/acp-14-11525-2014

Vertical redistribution of HNO3 through condensation, sedimentation and evaporation of large HNO3-containing particles inside polar stratospheric clouds (PSCs) plays an important role in the chemistry of the Arctic winter stratosphere. In situ observations by the particle probe FSSP-100 during the RECONCILE campaign indicate unexpected large potential NAT (nitric acid trihydrate) particles inside PSCs. The observations can hardly be explained assuming particles with compact morphology and spherical shape due to limited growing time at temperatures below the existence temperature of NAT (TNAT). Utilizing simulations by the CLaMS and measurements by the airborne Fourier transform infrared spectrometer MIPAS-STR we study the impact of reduced settling velocities of NAT particles on vertical HNO3 redistribution. Reduced settling velocities are expected for spherical NAT particles with low mass density or aspheric NAT particles that might explain the maximum sizes of the particles observed in situ. The results of our study support the hypothesis that denitrification is produced by significantly aspheric (i.e. columnar) compact NAT particles which are characterised by reduced settling velocities.