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| Titel |
The Limb of the Martian Atmosphere in Mars Express' High Resolution Stereo Camera Images |
| VerfasserIn |
Oliver J. Stenzel, H. Uwe Keller, Nico M. Hoekzema, Wojciech J. Markiewicz, Harald Hoffmann |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053101
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| Zusammenfassung |
| The Martian atmosphere often shows horizontal layers of haze up to altitudes of about
80 km. The High Resolution Stereo Camera, HRSC (Neukum et al. 2004; Jaumann
et al. 2007) has been used to sample the planetary limb. HRSC is a push broom
scanner with nine line sensors pointing in different directions to facilitate stereoscopic
imaging. Four of the sensors have colour filters at 440Â nm, 530Â nm, 750Â nm and
970Â nm, respectively. The five other sensors all have filters centred at 650Â nm. These
panchromatic filters have a much wider bandpass than the four colour filters. It is not
possible to obtain and compare profiles at the same location and at the same time with
different sensors, but still, averages of profiles over place and season can provide us
with information about typical atmospheric conditions. We examine the HRSC
planetary limb data and analyse the seasonal and latitudinal variations of the maximum
altitude of the haze layer and of the occurrence of high altitude detached hazes.
Most observations were made with the panchromatic channels. There are also many
observations with the blue and green sensors and only a few were made in the red
and infra red channels. We find the best data coverage in northern spring in the
northern most latitudes. For obvious reasons, we do not have any data during polar
nights.
The colour observations show on average variations of aerosol composition with latitude and
altitude. We make some comparisons with earlier work, i.e. from the Viking Orbiter
and Mars Express SPICAM experiments. In contrast to the SPICAM instrument,
which is used for night time stellar occultation measurements by Montmessin et al.,
HRSC observes the atmosphere during daytime, which makes it possible to compare
night and daytime observations. The seasonal variations of maximum altitude of the
aerosols is in good agreement with Jaquin et al. (1986) and with Montmessin et
al. (2006). The similarity between Montmessin’s results and ours is likely to be
due to the large annual variation of atmospheric dust load compared to the diurnal
cycle. |
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