Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 5 6 2005 10.5194/acp-5-1437-2005 http://www.atmos-chem-phys.net/5/1437/2005/ http://www.atmos-chem-phys.net/5/1437/2005/acp-5-1437-2005.html http://www.atmos-chem-phys.net/5/1437/2005/acp-5-1437-2005.pdf 1437 1448 2005-06-15 Simulation of denitrification and ozone loss for the Arctic winter 2002/2003 J.-U. Grooß G. Günther R. Müller P. Konopka S. Bausch H. Schlager C. Voigt C.M. Volk G. C. Toon Institut für Chemie und Dynamik der Geosphäre I: Stratosphäre (ICG I), Forschungszentrum Jülich, Jülich, Germany Institut für Physik der Atmosphäre, DLR Oberpfaffenhofen, Germany Institut für Meteorologie und Geophysik, Universität Frankfurt, Germany Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA We present simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the Arctic winter 2002/2003. We integrated a Lagrangian denitrification scheme into the three-dimensional version of CLaMS that calculates the growth and sedimentation of nitric acid trihydrate (NAT) particles along individual particle trajectories. From those, we derive the HNO<sub>3</sub> downward flux resulting from different particle nucleation assumptions. The simulation results show a clear vertical redistribution of total inorganic nitrogen ( ), with a maximum vortex average permanent removal of over 5ppb in late December between 500 and 550K and a corresponding increase of of over 2ppb below about 450K. The simulated vertical redistribution of is compared with balloon observations by MkIV and in-situ observations from the high altitude aircraft Geophysica. Assuming a globally uniform NAT particle nucleation rate of 7.8x10<sup>-6</sup>cm<sup>-3</sup>h<sup>-1</sup> in the model, the observed denitrification is well reproduced. <P style="line-height: 20px;"> In the investigated winter 2002/2003, the denitrification has only moderate impact (&le;14%) on the simulated vortex average ozone loss of about 1.1ppm near the 460K level. At higher altitudes, above 600K potential temperature, the simulations show significant ozone depletion through -catalytic cycles due to the unusual early exposure of vortex air to sunlight.