ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-919-2005 4-D comparison method to study the NO<sub>y</sub> partitioning in summer polar stratosphere &ndash; Influence of aerosol burden Dufour G. 1 Payan S. 1 Lefèvre F. 2 Eremenko M. 1 Butz A. 3 Jeseck P. 1 Té Y. 1 Pfeilsticker K. 3 Camy-Peyret C. 1 Laboratoire de Physique Moléculaire et Applications, Université P. et M. Curie, Paris, France Service d’Aéronomie, Institut Pierre-Simon Laplace, Paris, France Institut für Umweltphysik, University of Heidelberg, Germany 21 03 2005 5 4 919 926 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/919/2005/acp-5-919-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/919/2005/acp-5-919-2005.pdf

On 21&ndash;22 August 2001, NO, NO<sub>2</sub> and HNO<sub>3</sub> mixing ratio profiles were measured at high latitudes during sunset and sunrise using the Limb Profile Monitor of the Atmosphere (LPMA) and the DOAS experiments under stratospheric balloon. Photochemical simulations using the chemistry module of the Reprobus Chemistry Transport Model (CTM) that are constrained by ozone and total NO<sub>y</sub> balloon observations reproduce well the partitioning of NO<sub>x</sub> and NO<sub>y</sub> when model results are calculated at the exact time and location of the measurement for each tangent altitude. Taking the recently recommended reaction rate coefficients for the NO<sub>y</sub> partitioning (JPL-2003) and using realistic aerosol surface area in order to initialise the model leads to an agreement between calculations and measurements better than 10% all over the covered altitude range.