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| Titel |
Diurnal variation of stratospheric and lower mesospheric HOCl, ClO and HO2 at the equator: comparison of 1-D model calculations with measurements by satellite instruments |
| VerfasserIn |
M. Khosravi, P. Baron, J. Urban, L. Froidevaux, A. I. Jonsson, Y. Kasai, K. Kuribayashi, C. Mitsuda, D. P. Murtagh, H. Sagawa, M. L. Santee, T. O. Sato, M. Shiotani, M. Suzuki, T. Clarmann, K. A. Walker, S. Wang |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 15 ; Nr. 13, no. 15 (2013-08-06), S.7587-7606 |
| Datensatznummer |
250085611
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| Publikation (Nr.) |
 copernicus.org/acp-13-7587-2013.pdf |
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| Zusammenfassung |
| 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-millimetre instruments and two infrared spectrometers are used,
namely from the Sub-Millimetre 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 data from the SMILES
instrument which measured at all local times over a period of
several months provides the possibility to verify the model and
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. Besides presenting the SMILES data, the study also
shows a first comparison of the latest MLS data (version 3.3) of
HOCl, ClO, and HO2 with other satellite observations, as well
as a first evaluation of HO2 observations made by Odin/SMR.
The MISU-1D model has been carefully initialised and
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 agree well in terms of absolute mixing ratios.
The differences between the day and night values of the model
are in good agreement with the observations although the amplitude of
the HO2 diurnal variation is 10–20% lower in the model than in the
observations. In particular, the data offered the
opportunity to study the reaction ClO+HO2 → HOCl+O2
in the lower mesosphere at 55 km. At this altitude the HOCl night-time
variation depends only on this reaction. The result of this analysis
points towards a value of the rate constant within the range of the JPL 2006
recommendation and the upper uncertainty limit of the JPL 2011 recommendation at 55 km. |
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