Seasonal Trends in Titan’s Atmosphere: Haze, Wind, and Clouds

• Main Author: Antonin Henri Bouchez
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2004
• Subjects: Hale; South Pole; South pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.425.3946; http://thesis.library.caltech.edu/4274/1/thesis.pdf

This dissertation is dedicated to Eleta Trejo-Cantwell, my friend and partner throughout this long and sometimes difficult process. iv I present an analysis of visible and near-infrared adaptive optics images and spectra of Titan taken over 43 nights between October 1997 and January 2003 with the AEOS 3.6-m, Palomar Hale 5-m, and W.M. Keck 10-m telescopes. These observations reveal a seasonally changing stratospheric haze layer, two distinct regions of condensate clouds in the southern hemisphere, the albedo of Titan’s surface, and the zonal wind field of the stratosphere. Transient convective CH4 clouds are identified near Titan’s south pole, rising to 16±5km above the surface. These clouds have been continuously present south of 70◦S since at least December 2001, currently account for 0.5–1 % of Titan’s 2 µm flux, and appear to be gradually brightening or thickening as the insolation of the south polar region increases. Above the polar clouds, an extensive but optically thin (τ ≈ 0.05 at 2 µm) cloud layer is noted near the tropopause south of 30◦S. Aside from the convective CH4 clouds near the south pole, Titan’s troposphere is free of aerosols with an upper limit of τ<0.01 on the