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| Titel |
Vertical structure of the Venus cloud top from the VeRa and VIRTIS observations onboard Venus Express |
| VerfasserIn |
Yeon Joo Lee, Dmitriy Titov, Silvia Tellmann, Giuseppe Piccioni, Arianna Piccialli, Martin Pätzold, Pierre Drossart |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250041825
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| Zusammenfassung |
| Vertical structure of the Venus clouds is important for understanding of the radiative energy
balance and the atmospheric dynamics. The structure of the cloud tops (75-65 km) is
especially poorly investigated since it falls between the altitude ranges sounded by solar/
stellar occultation and that studied by descent probes. In this work we analyse the data
from the radio science experiment VeRa and Visible and Infrared Thermal Imaging
Spectrometer (VIRTIS) onboard Venus Express. Radio sounding is insensitive to the clouds
and provides “true” temperature structure, while thermal IR spectra depend on
both temperature and aerosol distribution. Thus the joint analysis allows one to
constrain vertical structure of aerosol at the cloud tops and its latitudinal variations.
Using VeRa temperature profiles we fit VIRTIS spectra in the wavelength range of
4.5 - 5 μm by tuning two parameters in the exponential model of aerosol vertical
distribution: cloud top altitude of a unity optical thickness and scale height. We found that
the cloud top altitude decreased from ~66 km in the middle and low latitudes to
62-64 km in the polar regions. The scale height showed correlated changes from
3-4 km to less than 1 km. Radiative transfer modelling showed that thermal IR
spectrum is more sensitive to the cloud top altitude than to the aerosol scale height. |
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