Atmos. Chem. Phys. Discuss., 11, 20793-20822, 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.
The MIPAS HOCl climatology
T. von Clarmann1, B. Funke2, N. Glatthor1, S. Kellmann1, M. Kiefer1, O. Kirner3, B.-M. Sinnhuber1, and G. P. Stiller1
1Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Karlsruhe, Germany
2Instituto de Astrofísica de Andalucía, CSIC, Granada, Spain
3Karlsruhe Institute of Technology, Steinbuch Centre for Computing, Karlsruhe, Germany

Abstract. Monthly zonal mean HOCl measurements by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) are presented for the episode from June 2002 to March 2004. Highest molar mixing ratios are found at pressure levels between 6 and 2 hPa, whereby largest mixing ratios occasionally exceed 200 ppt. The mixing ratio maximum is generally at lower altitudes in the summer hemisphere than in the winter hemisphere except for chlorine activation conditions in polar vortices, where enhanced HOCl abundances are also found in the lower stratosphere. During nighttime the maximum is found at higher altitudes than during daytime. Particularly low values are found in subpolar regions in the winter hemisphere, coinciding with the mixing barrier formed by the polar vortex boundary. The Antarctic polar winter HOCl distribution in 2002, the year of the split of the southern polar vortex, resembles northern polar winters rather than other southern polar winters. Increased HOCl amounts in response to the so-called Halloween solar proton event in autumn 2003 affect the representativeness of data recorded during this particular episode. Calculations with the EMAC model reproduce the structure of the measured HOCl distribution but predict approximately 40 % less HOCl except during polar night in the mid-stratosphere where calculated HOCl mixing ratios exceed observed ones.

Citation: von Clarmann, T., Funke, B., Glatthor, N., Kellmann, S., Kiefer, M., Kirner, O., Sinnhuber, B.-M., and Stiller, G. P.: The MIPAS HOCl climatology, Atmos. Chem. Phys. Discuss., 11, 20793-20822, doi:10.5194/acpd-11-20793-2011, 2011.
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