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| Titel |
Spatial and temporal variations in Titan's surface temperatures from Cassini CIRS observations |
| VerfasserIn |
Valeria Cottini, Conor A. Nixon, Donald E. Jennings, Remco de Kok, Nicholas A. Teanby, Patrick G. J. Irwin, F. Michael Flasar |
| 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 |
250046357
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| Zusammenfassung |
| We report the study of Titan’s surface temperatures by wide analysis of the moon’s outgoing radiance through a spectral window in the thermal infrared at 19 μm (530 cm–1) characterized by low opacity. We modeled Cassini Composite Infrared Spectrometer (CIRS) far infrared spectra collected from 2004-2010, using a radiative transfer forward model combined with a non-linear optimal estimation inversion method. At low-latitudes, we agree with the HASI near-surface temperature of about 94 K at 10°S (Fulchignoni, M., et al. 2005). By zonally-averaging our results, we also find a systematic decrease from the equator toward the poles, hemispherically asymmetric, of ~1 K at 50 degrees south and ~3 K at 50 degrees north, in general agreement with a previous analysis of CIRS data (Jennings, D.E., et al., 2009), and with Voyager results from the previous northern winter. Subdividing the available database, corresponding to about one Titan season, into 3 consecutive periods, in order to avoid bias for eventual seasonal variations we found clear evidence of diurnal variations of the surface temperatures near the equator, observed for the first time: we find a trend of slowly increasing temperature from the morning to noon and increasing again towards the late afternoon. The diurnal change is ~1.5 K, in agreement with model predictions for a surface with a thermal inertia between 300 and 600 J m-2 s-1/2 K-1.
References
Fulchignoni, M., and 42 colleagues, 2005. In situ measurements of the physical characteristics of Titan's environment. Nature. 438, 785.
Jennings, D.E., and 19 colleagues, 2009. Titan's Surface Brightness Temperatures. Ap. J. L., Vol. 691, pp. L103-L105. |
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