Detection of Condensed Phase Methane in Titan's Lower Atmosphere with Near-IR Spectra from Keck/OSIRIS
Methane is close to its triple point at Titan's surface and is suspected to be involved in a methane-based meteorological cycle there. Clouds are routinely observed and the relative humidity profile of methane suggests the presence of drizzle and perhaps a cloud of solid methane particles. Despite the mounting evidence for solid and liquid methane in Titan's atmosphere, retrievals of haze opacities, cloud properties, and surface reflectivities from near-infrared spectra have not included opacity due to condensed-phase methane. We present spatially-resolved Keck/OSIRIS observations of Titan in H- and K-bands and use a two-stream radiative transfer model, which includes condensed-phase methane opacity, to report the altitude and column of liquid and particulate methane in Titan's lower atmosphere. Radiative transfer retrievals of surface absorption spectra (covering 1.48 to 2.3 microns) and observational limitations therein are discussed.
AAS/Division for Planetary Sciences Meeting Abstracts #39
- Pub Date:
- October 2007