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| Titel |
A Look Toward the Surface: Radiative Transfer Modelling in Titan's Atmosphere Using Cassini/VIMS data |
| VerfasserIn |
Thomas Cornet, Sebastien Rodriguez, Luca Maltagliati, Thomas Appéré, Christophe Sotin, Stéphane Le Mouélic, Pascal Rannou, Anezina Solomonidou, Mathieu Hirtzig, Bruno Bézard, Athena Coustenis, Robert H. Brown, Jason W. Barnes, Kevin H. Baines, Bonnie J. Buratti, Roger N. Clark, Phillip D. Nicholson |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148069
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| Publikation (Nr.) |
 EGU/EGU2017-12298.pdf |
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| Zusammenfassung |
| Saturn’s moon Titan possesses a thick and opaque atmosphere, strongly absorbing and
scattering in the infrared due to the presence of molecular gases (mostly N2 and CH4) and of
a thick organic haze. Despite the presence of this atmosphere, the Cassini Visual and Infrared
Mapping Spectrometer (VIMS) instrument is able to acquire images of Titan’s surface in
atmospheric transmission windows centered at 0.93, 1.08, 1.27, 1.59, 2.01, 2.7-2.8 and 5 μm
in the infrared [1]. These imaging capabilities already contributed to reveal and investigate
the geological diversity of Titan’s surface [2,3,4], but the interpretation of the data in terms
of surface composition is often limited due to the heavy processing required to
disentangle atmospheric to surface contributions. In this context, we are developing an
accurate and fast radiative transfer model and inversion scheme for Titan in order to
massively invert the Titan VIMS dataset (125 flybys, tens of thousands of data
cubes) and compute surface albedo maps to be used for geomorphological and
compositional mapping studies using Cassini/VIMS data. The present model operates in
plane-parallel approximation using the SHDOMPP solver [5], which mostly constrains
our inversions to the equatorial regions of Titan, where the viewing geometry is
suitable to the solver. Our inversion strategy in based on the calculation of reference
Look-Up Tables (LUTs) [6] with the radiative transfer direct model [6-8], on which we
perform a series of interpolations in order to retrieve the exact geometry of the data
(incidence, emission and azimuth angles) and the associated haze opacity factor and
surface albedo in order to match the input spectra. This methodology of inversion
allows us to process VIMS cubes and mosaics of VIMS cubes in a couple of hours
only (as compared to several days with classical approaches). We will apply this
model to regional VIMS mosaics composed of several flybys, such as the T13-T17
mosaic.
[1] Sotin C. et al. (2005), Nature ; [2] Barnes J.W. et al. (2007), Icarus ; [3] Barnes J.W. et
al. (2011), Icarus ; [4] Brown R.H. et al. (2008), Nature ; [5] Evans K. (2007), JAS ; [6]
Maltagliati L. et al. (2015), EPSC. [7] Solomonidou A. et al. (2014), JGR ; [8] Solomonidou
A. et al. (2016), Icarus. |
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