Titan Surface Temperatures from Cassini CIRS

Abstract to be submitted to'`Cassini-Huygens Project: Huygens Legacy and Future Titan Exploration"Barcelona, Spain, 13-15 January 2010Titan's Surface Temperatures from Cassini CIRSDonald E. Jennings, Valeria Cottini" Conor A. Nixon'' 'Goddard Space Flight Center, Greenbelt, MLA 20771 USA Z university rlf Maryland, College Park, ,SID 20742 GSA The surface brightness temperature of Titan can be measured from Cassini through aspectral window at 19 microns where the atmosphere is low in opacity. The CompositeInfrared Spectrometer' (CIRS) on Cassini observes this wavelength in its far-infraredchannel. Because the Cassini tour has provided global coverage and a range of viewinggeometries, CIRS has been able to go beyond the earlier flyby results of Voyager IRIS' 3 Near the equator, CIRS measures the zonally-averaged surface brightness temperature tobe 917 K, very close to the temperature found at the surface by Huygens 4 . Latitude mapsshow that Titan's surface temperatures drop off by about 2 K toward the south and byabout 3 K toward the north. This temperature distribution is consistent with Titan's latenorthern winter when the data were taken. As the seasons progress, CIRS is continuing tosearch for corresponding changes in the temperatures of the surface and loweratmosphere. CIRS is also extending global mapping to both latitude and longitude to lookfor correlations between surface temperatures and geological features.