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| Titel |
Thermal structure and dynamics of the Martian upper atmosphere at solar minimum from global circulation model simulations |
| VerfasserIn |
T. Moffat-Griffin, A. D. Aylward, W. Nicholson |
| 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 ; 25, no. 10 ; Nr. 25, no. 10 (2007-11-06), S.2147-2158 |
| Datensatznummer |
250015929
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| Publikation (Nr.) |
 copernicus.org/angeo-25-2147-2007.pdf |
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| Zusammenfassung |
| Simulations of the Martian upper atmosphere have been produced from a
self-consistent three-dimensional numerical model of the Martian thermosphere
and ionosphere, called MarTIM. It covers an altitude range of 60 km to
the upper thermosphere, usually at least 250 km altitude. A radiation scheme
is included that allows the main sources of energy input, EUV/UV and IR
absorption by CO2 and CO, to be calculated. CO2,
N2 and O are treated as the major gases in MarTIM, and are
mutually diffused (though neutral chemistry is ignored). The densities of
other species (the minor gases), CO, Ar, O2 and
NO, are based on diffusive equilibrium above the turbopause. The
ionosphere is calculated from a simple photoionisation and charge exchange
routine though in this paper we will only consider the thermal and dynamic
structure of the neutral atmosphere at solar minimum conditions. The
semi-diurnal (2,2) migrating tide, introduced at MarTIM's lower boundary,
affects the dynamics up to 130 km. The Mars Climate Database
(Lewis et al., 2001) can be used as a lower boundary in MarTIM. The effect of this is
to increase wind speeds in the thermosphere and to produce small-scale
structures throughout the thermosphere. Temperature profiles are in good
agreement with Pathfinder results. Wind velocities are slightly lower
compared to analysis of MGS accelerometer data (Withers,
2003). The novel step-by-step approach of adding in new features to MarTIM has resulted in
further understanding of the drivers of the Martian thermosphere. |
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