TRAMS: A new dynamic cloud model for Titan's methane clouds

Abstract

Convective clouds on Titan may play an important role in climate dynamics, atmospheric chemistry, and the overall volatile cycle. To study the formation and evolution of these clouds, we have developed the Titan Regional Atmospheric Modeling System (TRAMS). TRAMS is a three-dimensional, time-dependent, coupled fully compressible dynamic and microphysical model capable of simulating methane and ethane clouds in Titan's atmosphere. In initial model tests over a two-dimensional domain, a warm bubble or random temperature perturbations trigger a parcel of air to rise. For an initial methane profile with a 60% surface humidity, convection occurs for positive temperature perturbations of 1 K or greater. Cloud tops are between 25 and 35 km, consistent with observations of the south polar clouds. For a drier methane environment in the lower atmosphere, characteristic of the Huygens landing site, convection does not occur, but a layer of stratiform clouds is able to form at altitudes around 10 km. Copyright 2007 by the American Geophysical Union.