Atmos. Chem. Phys. Discuss., 12, 21065-21104, 2012
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Diurnal variation of stratospheric HOCl, ClO and HO2 at the equator: comparison of 1-D model calculations with measurements of satellite instruments
M. Khosravi1, P. Baron2, J. Urban1, L. Froidevaux3, A. I. Jonsson4, Y. Kasai2,5, K. Kuribayashi2,5, C. Mitsuda6, D. P. Murtagh1, H. Sagawa2, M. L. Santee3, T. O. Sato2,5, M. Shiotani7, M. Suzuki8, T. von Clarmann9, K. A. Walker4, and S. Wang3
1Department of Earth and Space Sciences, Chalmers University of Technology, Gothenburg, Sweden
2National Institute of Information and Communications Technology, Tokyo, Japan
3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
4Tokyo Institute of Technology, Kanagawa, Japan
5Tokyo Institute of Technology, Yokohama, Japan
6Fujitsu FIP Corporation, Tokyo, Japan
7Research Institute for Sustainable Humanosphere, Kyoto University, Kyoto, Japan
8Japan Aerospace Exploration Agency, Ibaraki, Japan
9Karlsruhe Institute of Technology, Institute for Meteorology and Climate Research, Karlsruhe, Germany

Abstract. The diurnal variation of HOCl and the related species ClO, HO2 and HCl measured by satellites has been compared with the results of a one-dimensional photochemical model. The study compares the data from various limb-viewing instruments with model simulations from the middle stratosphere to the lower mesosphere. Data from three sub-millimeter instruments and two infrared spectrometers are used, namely from the Sub-Millimeter Radiometer (SMR) on board Odin, the Microwave Limb Sounder (MLS) on board Aura, the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES) on the International Space Station, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT, and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on board SCISAT. Inter-comparison of the measurements from instruments on sun-synchronous satellites (SMR, MLS, MIPAS) and measurements from solar occultation instruments (ACE-FTS) is challenging since the measurements correspond to different solar zenith angles (or local times). However, using a model which covers all solar zenith angles and the new SMILES instrument which measures at all local times over a period of several months provides the possibility to indirectly compare the diurnally variable species. The satellite data were averaged for latitudes of 20° S to 20° N for the SMILES observation period from November 2009 to April 2010 and were compared at three altitudes: 35, 45 and 55 km. This study presents the first evaluation of HO2 Odin/SMR data and also the first comparison of the new SMILES data and the latest version of MLS (version 3.3) with other satellite observations. The MISU-1D model has been run for conditions and locations of the observations. The diurnal cycle features for the species investigated here are generally well reproduced by the model. The satellite observations and the model generally agree well in terms of absolute mixing ratios as well as differences between the day and night values. This confirms that gas phase chemistry of these species based on latest recommendations of reaction rate constants is fairly well understood.

Citation: Khosravi, M., Baron, P., Urban, J., Froidevaux, L., Jonsson, A. I., Kasai, Y., Kuribayashi, K., Mitsuda, C., Murtagh, D. P., Sagawa, H., Santee, M. L., Sato, T. O., Shiotani, M., Suzuki, M., von Clarmann, T., Walker, K. A., and Wang, S.: Diurnal variation of stratospheric HOCl, ClO and HO2 at the equator: comparison of 1-D model calculations with measurements of satellite instruments, Atmos. Chem. Phys. Discuss., 12, 21065-21104, doi:10.5194/acpd-12-21065-2012, 2012.
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