2.5
Methane in Titan's weather and climate
Jonathan L. Mitchell, Univ. of California, Los Angeles, CA
The Cassini/Huygens mission in its exploration of Saturn's largest moon, Titan, reveals a world remarkably similar to Earth. Perhaps most notably, methane actively cycles between the surface and atmosphere, creating a methane “hydrology” much like our own. Gaseous methane, like water, is an efficient infrared absorber, and therefore Titan has the potential to go into a runaway greenhouse. However, Titan lacks a global surface ocean of methane; the surface is largely desert-like with much of the low latitudes covered in seas of sand dunes. Hydrocarbon lakes exist only at high latitudes while fluvial erosion features are evident over much of the globe. By direct analogy to the Earth's tropical climate, I will demonstrate mechanisms which sustain Titan's climate zones using a suite of simplified climate models. These models predict convective methane clouds, which have primarily been observed near the solsticial pole, will migrate to the opposite hemisphere during the current equinoctial season as Titan's unsteady Hadley cell switches directions, a phenomenon which may already be occurring. Earth's climate has proved a useful template for understanding Titan's climate, and given time and more extensive observations, Titan could provide insight into past and future climates on Earth.
Session 2, Numerical modeling of planetary meteorology and climate dynamics
Wednesday, 20 January 2010, 4:00 PM-5:30 PM, B314
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