Atmos. Chem. Phys. Discuss., 11, 9407-9514, 2011
© Author(s) 2011. This work is distributed
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Composition changes after the "Halloween" solar proton event: the High-Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study
B. Funke1, A. Baumgaertner2, M. Calisto3, T. Egorova4, C. H. Jackman5, J. Kieser6, A. Krivolutsky7, M. López-Puertas1, D. R. Marsh8, T. Reddmann9, E. Rozanov3,4, S.-M. Salmi11,12, M. Sinnhuber9,10, G. P. Stiller9, P. T. Verronen11, S. Versick9,14, T. von Clarmann9, T. Y. Vyushkova7, N. Wieters10, and J. M. Wissing13
1Instituto de Astrof{í}sica de Andalucía, CSIC, Granada, Spain
2Max Planck Institute for Chemistry, Mainz, Germany
3Institute for Atmospheric and Climate Science ETH, Zurich, Switzerland
4Physical-Meteorological Observatory/World Radiation Center, Davos, Switzerland
5NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
6Max Planck Institute for Meteorology, Hamburg, Germany
7Central Aerological Observatory (CAO), Dolgoprudny, Moscow Region, Russia
8National Center for Atmospheric Research, Boulder, CO, USA
9Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Karlsruhe, Germany
10Institute of Environmental Physics, University of Bremen, Bremen, Germany
11Earth Observation Unit, Finnish Meteorological Institute, Helsinki, Finland
12Department of Physics, University of Helsinki, Helsinki, Finland
13FB Physik, University of Osnabrück, Osnabrück, Germany
14Steinbuch Centre for Computing, Karlsruhe, Germany

Abstract. We have compared composition changes of NO, NO2, H2O2, O3, N2O, HNO3, N2O5, HNO4, ClO, HOCl, and ClONO2 as observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat in the aftermath of the "Halloween" solar proton event (SPE) in October/November 2003 at 25–0.01 hPa in the Northern Hemisphere (40–90° N) and simulations performed by the following atmospheric models: the Bremen 2d Model (B2dM) and Bremen 3d Chemical Transport Model (B3dCTM), the Central Aerological Observatory (CAO) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, the modeling tool for SOlar Climate Ozone Links studies (SOCOL and SOCOLi), and the Whole Atmosphere Community Climate Model (WACCM4). The large number of participating models allowed for an evaluation of the overall ability of atmospheric models to reproduce observed atmospheric perturbations generated by SPEs, particularly with respect to NOy and ozone changes. We have further assessed the meteorological conditions and their implications on the chemical response to the SPE in both the models and observations by comparing temperature and tracer (CH4 and CO) fields.

Simulated SPE-induced ozone losses agree on average within 5% with the observations. Simulated \noy enhancements around 1 hPa, however, are typically 30% higher than indicated by the observations which can be partly attributed to an overestimation of simulated electron-induced ionization. The analysis of the observed and modeled NOy partitioning in the aftermath of the SPE has demonstrated the need to implement additional ion chemistry (HNO3 formation via ion-ion recombination and water cluster ions) into the chemical schemes. An overestimation of observed H2O enhancements by all models hints at an underestimation of the OH/HO2 ratio in the upper polar stratosphere during the SPE. The analysis of chlorine species perturbations has shown that the encountered differences between models and observations, particularly the underestimation of observed ClONO2 enhancements, are related to a smaller availability of ClO in the polar night region already before the SPE. In general, the intercomparison has demonstrated that differences in the meteorology and/or initial state of the atmosphere in the simulations causes a relevant variability of the model results, even on a short timescale of only a few days.

Citation: Funke, B., Baumgaertner, A., Calisto, M., Egorova, T., Jackman, C. H., Kieser, J., Krivolutsky, A., López-Puertas, M., Marsh, D. R., Reddmann, T., Rozanov, E., Salmi, S.-M., Sinnhuber, M., Stiller, G. P., Verronen, P. T., Versick, S., von Clarmann, T., Vyushkova, T. Y., Wieters, N., and Wissing, J. M.: Composition changes after the "Halloween" solar proton event: the High-Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study, Atmos. Chem. Phys. Discuss., 11, 9407-9514, doi:10.5194/acpd-11-9407-2011, 2011.
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