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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-772
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
11 Oct 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Local Time Dependence of Polar Mesospheric Clouds: A model study
Francie Schmidt, Gerd Baumgarten, Uwe Berger, Jens Fiedler, and Franz-Josef Lübken Leibniz-Institute of Atmospheric Physics, Rostock University, Kühlungsborn, Germany
Abstract. The Mesospheric Ice Microphysics And tranSport model (MIMAS) is used to study local time (LT) variations of polar mesospheric clouds (PMC) in the northern hemisphere during the period from 1979 to 2013. We investigate the tidal behavior of brightness, altitude and occurrence frequency and find a good agreement between model and lidar observations. Mean ice water content (IWC) values from MIMAS also match those from satellite observations. In the latitudinal band of 67.5°–70.5° N the IWC maximum throughout the day occurs at about 3 LT and the minimum around 18 LT with a ratio of maximum to minimum of 10. At the peak of the PMC layer the ice particle size varies by about 30 % while the median number density varies by a factor of 2 throughout the day. Furthermore, the absolute tidal variation of IWC generally increases towards higher latitudes and the time of maximum IWC changes from about 4 to 0 LT for latitudes from 63° N to 81° N. In the period from 1979 to 2013 we find an increase of the tidal amplitudes. The linear trend terms of diurnal and semidiurnal variations are calculated to be 3.4 and 1.4 g/km2/dec. The persistent features of strong tidal modulations are caused by tidal structures in background parameters. The temperature varies by about 2 K and water vapor by about 3 ppmv at the altitude of ice particle sublimation near 81.5 km.

Citation: Schmidt, F., Baumgarten, G., Berger, U., Fiedler, J., and Lübken, F.-J.: Local Time Dependence of Polar Mesospheric Clouds: A model study, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-772, in review, 2017.
Francie Schmidt et al.
Francie Schmidt et al.
Francie Schmidt et al.

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Short summary
Local time variations of polar mesospheric clouds (PMC) in the northern hemisphere are studied using a combination of a global circulation model and a microphysical model. We investigate the brightness, altitude and occurrence of the clouds and find a good agreement between model and observations. The variations are caused by tidal structures in background parameters. The temperature varies by about 2 K and water vapor by about 3 ppmv at the altitude of ice particle sublimation near 81.5 km.
Local time variations of polar mesospheric clouds (PMC) in the northern hemisphere are studied...
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