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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-503
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Jun 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Denitrification, dehydration and ozone loss during the Arctic winter 2015/2016
Farahnaz Khosrawi1, Oliver Kirner2, Björn-Martin Sinnhuber1, Sören Johansson1, Michael Höpfner1, Michelle L. Santee3, Lucien Froidevaux3, Jörn Ungermann4, Roland Ruhnke1, Wolfgang Woiwode1, Hermann Oelhaf1, and Peter Braesicke1 1Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
2Steinbuch Centre for Computing, Karlsruhe Institute of Technology, Karlsruhe, Germany
3Jet Propulsion Laboratory, California Institute of Technology, California, USA
4Institute of Energy and Climate Research, Forschungszentrum Jülich, Jülich, Germany
Abstract. The Arctic winter 2015/2016 was one of the coldest stratospheric winters in recent years. A stable vortex formed by early December and the early winter was exceptionally cold. Cold pool temperatures dropped below the Nitric Acid Trihydrate (NAT) existence temperature of about 195 K, thus allowing Polar Stratospheric Clouds (PSCs) to form. The low temperatures in the polar stratosphere persisted until early March allowing chlorine activation and catalytic ozone destruction. Satellite observations indicate that sedimentation of PSC particles led to denitrification as well as dehydration of stratospheric layers. Model simulations of the Arctic winter 2015/2016 nudged toward European Center for Medium-Range Weather Forecasts (ECMWF) analyses data were performed with the atmospheric chemistry–climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the Polar Stratosphere in a Changing Climate (POLSTRACC) campaign. POLSTRACC is a High Altitude and LOng Range Research Aircraft (HALO) mission aimed at the investigation of the structure, composition and evolution of the Arctic Upper Troposphere and Lower Stratosphere (UTLS). The chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, polar stratospheric clouds as well as cirrus clouds are investigated. In this study an overview of the chemistry and dynamics of the Arctic winter 2015/2016 as simulated with EMAC is given. Further, chemical-dynamical processes such as denitrification, dehydration and ozone loss during the Arctic winter 2015/2016 are investigated. Comparisons to satellite observations by the Aura Microwave Limb Sounder (Aura/MLS) as well as to airborne measurements with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) performed on board of HALO during the POLSTRACC campaign show that the EMAC simulations are in fairly good agreement with observations. We derive a maximum polar stratospheric O3 loss of ~ 2 ppmv or 100 DU in terms of column in mid March. The stratosphere was denitrified by about 8 ppbv HNO3 and dehydrated by about 1 ppmv H2O in mid to end of February. While ozone loss was quite strong, but not as strong as in 2010/2011, denitrification and dehydration were so far the strongest observed in the Arctic stratosphere in the at least past 10 years.

Citation: Khosrawi, F., Kirner, O., Sinnhuber, B.-M., Johansson, S., Höpfner, M., Santee, M. L., Froidevaux, L., Ungermann, J., Ruhnke, R., Woiwode, W., Oelhaf, H., and Braesicke, P.: Denitrification, dehydration and ozone loss during the Arctic winter 2015/2016, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-503, in review, 2017.
Farahnaz Khosrawi et al.
Farahnaz Khosrawi et al.
Farahnaz Khosrawi et al.

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Short summary
The Arctic winter 2015/2016 was one of the coldest winters in recent years allowing extensive PSC formation and chlorine activation. Model simulations of the Arctic winter 2015/2016 were performed with the atmospheric chemistry–climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). We find that ozone loss was quite strong, but not as strong as in 2010/2011, denitrification and dehydration were so far the strongest observed in the Arctic stratosphere in the at least past 10 years.
The Arctic winter 2015/2016 was one of the coldest winters in recent years allowing extensive...
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