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| Titel |
Modelling of Titan's middle atmosphere with the IPSL climate model |
| VerfasserIn |
Jan Vatant d'Ollone, Sébastien Lebonnois, Sandrine Guerlet |
| 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 |
250146164
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| Publikation (Nr.) |
 EGU/EGU2017-10169.pdf |
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| Zusammenfassung |
| Titan’s 3-dimensional Global Climate Model developed at the Institute Pierre-Simon Laplace
has already demonstrated its efficiency to reproduce and interpret many features of the
Saturnian moon’s climate (e.g. Lebonnois et al., 2012). However, it suffered from limits at the
top of the model, with temperatures far warmer than the observations and no stratopause
simulated. To interpret Cassini’s overall observations of seasonal effects in the middle
atmosphere (e.g. Vinatier et al., 2015), a satisfying modelling of the temperature profile in
this region was first required.
Latest developments in the GCM now enable a correct modelling of the temperature
profile in the middle atmosphere. In particular, a new, more flexible, radiative transfer scheme
based on correlated-k method has been set up, using up-to-date spectroscopic data. Special
emphasis is put on the too warm upper stratospheric temperatures in the former model that
were due to the absence of the infrared ν4 methane line (7.7 μm) in the radiative
transfer. While it was usually neglected in the tropospheric radiative models, this
line has a strong cooling effect in Titan’s stratospheric conditions and cannot be
neglected.
In this new version of the GCM, the microphysical model is temporarily switched off and
we use a mean profile for haze opacity (Lavvas et al., 2010). The circulation in
the middle atmosphere is significantly improved by this new radiative transfer.
The new 3-D simulations also show an interesting feature in the modeled vertical
profile of the zonal wind as the minimum in low stratosphere is now closer to the
observations.
Works in progress such as the vertical extension and the computation of the radiative
effect of the seasonal variations of trace components will also be presented.
- Lavvas P. et al., 2010. Titan’s vertical aerosol structure at the Huygens landing
site: Constraints on particle size, density, charge, and refractive index. Icarus 210,
832-842.
- Lebonnois S. et al., 2012. Titan Global Climate Model: new 3-dimensional version of the
IPSL Titan GCM. Icarus 218, 707-722.
- Vinatier S. et al., 2015. Seasonal variations in Titan’s middle atmosphere during
the northern spring derived from Cassini/CIRS observations. Icarus 250, 95-115. |
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