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| Titel |
Altimetry of the Venus cloud tops from the Venus Express observations |
| VerfasserIn |
N. Ignatiev, D. V. Titov, G. Piccioni, P. Drossart, W. J. Markiewicz, V. Cottini, Th. Roatsch, M. Almeida, N. Manoel |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250028808
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| Zusammenfassung |
| Spectrometer (VIRTIS) and Venus Monitoring Camera (VMC) onboard the Venus Express
spacecraft are used to map the cloud top altitude and to relate it to the UV markings. The
cloud top altitude is retrieved from the depth of CO2 absorption band at 1.6 μm. In low and
middle latitudes the cloud top is located at 74±1 km. It decreases poleward of ±50º and
reaches 63–69 km in the polar regions. This depression coincides with the eye of the
planetary vortex. Cloud top altitude experiences fast variations of about 1 km in tens
of hours, while larger long-term variations of about several kilometers have been
observed only at high latitudes. UV markings correlate with the cloud altimetry,
however the difference between adjacent UV dark and bright regions do not exceed
several hundred meters. Surprisingly, CO2 absorption bands are often weaker in
the dark UV features, indicating that the clouds may be located there even few
hundred meters higher. Dark UV spiral arms, which are often seen at about –70 º, thus
formally, correspond to higher altitudes or to the regions with strong latitudinal
gradient of the cloud top altitude. Cloud altimetry in the polar region reveals the
structure that correlates with the thermal emission maps but is invisible in UV images.
This implies that the UV optically thick polar hood is transparent in the near IR. |
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