Titan Surface Temperatures from Cassini CIRS
Abstract
Thermal radiation from the surface of Titan reaches space through a spectral window at 19-microns wavelength. After removing the effects of the atmosphere, measurement of this radiance gives the brightness temperature of the surface. The Composite Infrared Spectrometer1 (CIRS) has made such measurements during the Cassini prime mission. These observations cover a wide range of emission angles, thereby constraining the contributions from atmospheric radiance and opacity. With the more complete latitude coverage and much larger dataset, we have been able to improve upon the original results from Voyager IRIS.2,3 CIRS measures an equatorial surface brightness temperature, averaged over longitude, of 93.7±0.6 K. This agrees with the HASI4 temperature at the Huygens landing site. The latitude dependence of surface brightness temperature exhibits an approximately 2 K decrease toward the South Pole and 3 K decrease toward the North Pole. The lower surface temperatures seen at high latitudes are consistent with conditions expected for lake formation.
1Flasar, F. M. et al., Space Science Reviews 115</u>, 169 (2004). 2Flasar, F. M., Samuelson, R. E., & Conrath, B. J., Nature 292</u>, 693 (1981). 3Courtin, R., & Kim, S. J., Planetary and Space Science 50</u>, 309 (2002). 4Fulchignoni, M. et al., Nature 438</u>, 785 (2005).- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #40
- Pub Date:
- September 2008
- Bibcode:
- 2008DPS....40.2303J