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E.F. Young (SwRI), P. Rannou (Service d'Aeronomie), C.P. McKay (NARC), C.A. Griffith (NAU), K. Noll (STSci)
We continue our analysis of Titan's haze distribution using a set of WFPC2 images taken at seven wavelengths ranging from 619 to 953 nm. These images probe Titan's atmosphere from the surface to altitudes of roughly 100 km. From these cycle 6 images (obtained in late 1996) we find that the total optical depth due to haze ranges from 1.7 in the north to nearly 3 in the south. Most interesting are the vertical haze profiles, which show a gap across all latitudes in the region from 40 to 70 km. One explanation for this gap might be that ethane (and methane at lower altitudes) condenses onto aerosols near 70 km. These particles then descend relativly quickly until the shell of volatile material evaporates in the lower atmosphere, resulting in an intermediate zone of low haze concentration.
We present evidence that the surface albedo at 940 nm is less than 0.2. We also discuss the sensitivity of the haze profiles to the assumed distribution of atmospheric methane. Finally, we find a local concentration of haze over the northern hemisphere from the surface to 15 km.