Capability Development for Simulation of Titan's Methane Convection, 15-9560Printer Friendly Version
Inclusive Dates: 10/01/05 Current
Background - This project seeks to develop the capability for numerically simulating convective methane clouds in the Titan atmosphere, the Earth-like moon of Saturn. This is a timely proposal because of the increased attention Titan has received from the successful arrival of the Cassini spacecraft currently in orbit around Saturn and the Huygens descent probe, which landed on the surface of Titan in January. One of the most pressing questions about Titan is the nature of the methane cycle, which has been likened to the hydrologic cycle of Earth. Convective methane clouds, which have been imaged from Earth and most recently by the Cassini orbiter, may play an important role in the methane cycle and may produce precipitation that alters the surface, just as convective water clouds do on Earth. We will study the structure and dynamics of these clouds by modifying a numerical cloud model currently used for Earth and Mars.
Approach - We will adapt a version of the Regional Atmospheric Modeling System (RAMS) (Rafkin, et al., 2001) to Titan. RAMS is a numerical code designed to simulate the local and regional (but not global coverage) weather on Earth and Mars. It can be used to simulate phenomena such as convective clouds that are too small to be modeled with the large grid sizes of the perhaps better-known General Circulation Models (GCMs). The nested grid structure of RAMS allows for the resolution of small-scale (kilometer-sized) phenomena such as thunderstorms embedded in the larger-scale environment modeled on a coarser grid. The model utilizes nonhydrostatic physics and contains more sophisticated microphysical routines than GCMs.
Accomplishments - This project began less than a month ago. To date, we have successfully modified the necessary constants appropriate for Titan and have implemented a simple methane condensation scheme. Currently, we are working to couple the sophisticated bin-microphysical parameterization to the RAMS model core.