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| Titel |
Estimates of eddy turbulence consistent with seasonal variations of atomic oxygen and its possible role in the seasonal cycle of mesopause temperature |
| VerfasserIn |
M. N. Vlasov, M. C. Kelley |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 28, no. 11 ; Nr. 28, no. 11 (2010-11-18), S.2103-2110 |
| Datensatznummer |
250016914
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| Publikation (Nr.) |
 copernicus.org/angeo-28-2103-2010.pdf |
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| Zusammenfassung |
| According to current understanding, adiabatic cooling and heating
induced by the meridional circulation driven by gravity waves is the major
process for the cold summer and warm winter polar upper mesosphere. However,
our calculations show that the upward/downward motion needed for adiabatic
cooling/heating of the summer/winter polar mesopause simultaneously induces
a seasonal variation in both the O maximum density and the altitude of the
[O] peak that is opposite to the observed variables generalized by the
MSISE-90 model. It is usually accepted that eddy turbulence can produce the
[O] seasonal variations. Using this approach, we can infer the eddy
diffusion coefficient for the different seasons. Taking these results and
experimental data on the eddy diffusion coefficient, we consider in detail
and estimate the heating and cooling caused by eddy turbulence in the summer
and winter polar upper mesosphere. The seasonal variations of these
processes are similar to the seasonal variations of the temperature and
mesopause. These results lead to the conclusion that heating/cooling by eddy
turbulence is an important component in the energy budget and that adiabatic
cooling/heating induced by upward/downward motion cannot dominate in the
mesopause region. Our study shows that the impact of the dynamic process,
induced by gravity waves, on [O] distributions must be included in models of
thermal balance in the upper mesosphere and lower thermosphere (MLT) for a
consistent description because (a) the [O] distribution is very sensitive to
dynamic processes, and (b) atomic oxygen plays a very important role in
chemical heating and infrared cooling in the MLT. To our knowledge, this is
the first attempt to consider this aspect of the problem. |
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