Articles | Volume 14, issue 2
Atmos. Chem. Phys., 14, 1055–1073, 2014

Special issue: Chemistry, microphysics and dynamics of the polar stratosphere:...

Atmos. Chem. Phys., 14, 1055–1073, 2014

Research article 29 Jan 2014

Research article | 29 Jan 2014

Nitric acid trihydrate nucleation and denitrification in the Arctic stratosphere

J.-U. Grooß1, I. Engel1,2, S. Borrmann3,4, W. Frey4,*, G. Günther1, C. R. Hoyle2,5, R. Kivi6, B. P. Luo2, S. Molleker3, T. Peter2, M. C. Pitts7, H. Schlager8, G. Stiller9, H. Vömel10, K. A. Walker11, and R. Müller1 J.-U. Grooß et al.
  • 1Institut für Energie- und Klimaforschung – Stratosphäre (IEK-7), Forschungszentrum Jülich, Germany
  • 2Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland
  • 3Institut für Physik der Atmosphäre, Johannes-Gutenberg-Universität Mainz, Germany
  • 4Abteilung Partikelchemie, Max Planck Institut für Chemie, Mainz, Germany
  • 5Paul Scherrer Institute, Villigen, Switzerland
  • 6Finnish Meteorological Institute, Sodankylä, Finnland
  • 7NASA Langley Research Center, Hampton, VA, USA
  • 8Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany
  • 9Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
  • 10Meteorological Observatory Lindenberg, Deutscher Wetterdienst, Germany
  • 11Department of Physics, University of Toronto, Ontario, Canada
  • *now at: School of Earth Sciences, The University of Melbourne, Melbourne, Australia

Abstract. Nitric acid trihydrate (NAT) particles in the polar stratosphere have been shown to be responsible for vertical redistribution of reactive nitrogen (NOy). Recent observations by Cloud–Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the CALIPSO satellite have been explained in terms of heterogeneous nucleation of NAT on foreign nuclei, revealing this to be an important formation pathway for the NAT particles. In state of the art global- or regional-scale models, heterogeneous NAT nucleation is currently simulated in a very coarse manner using a constant, saturation-independent nucleation rate. Here we present first simulations for the Arctic winter 2009/2010 applying a new saturation-dependent parametrisation of heterogeneous NAT nucleation rates within the Chemical Lagrangian Model of the Stratosphere (CLaMS). The simulation shows good agreement of chemical trace species with in situ and remote sensing observations. The simulated polar stratospheric cloud (PSC) optical properties agree much better with CALIOP observations than those simulated with a constant nucleation rate model. A comparison of the simulated particle size distributions with observations made using the Forward Scattering Spectrometer Probe (FSSP) aboard the high altitude research aircraft Geophysica, shows that the model reproduces the observed size distribution, except for the very largest particles above 15 μm diameter. The vertical NOy redistribution caused by the sedimentation of the NAT particles, in particular the denitrification and nitrification signals observed by the ACE-FTS satellite instrument and the in situ SIOUX instrument aboard the Geophysica, are reproduced by the improved model, and a small improvement with respect to the constant nucleation rate model is found.

Final-revised paper