HR: 0800h
AN: P11C-0132    [Abstracts]
TI: Effects of moist convection on the large-scale circulation of Jupiter and Saturn
AU: * Showman, A P
EM: showman@lpl.arizona.edu
AF: University of Arizona, Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 United States
AB: The question of what causes the numerous east-west zonal jets on the giant planets has remained a mystery since high-resolution Pioneer and Voyager images were returned in the 1970s. A probable hypothesis is that cloud-level turbulence undergoes an inverse energy cascade that reorganizes the energy into zonal jets, and thunderstorms provide one of the major sources of such turbulence. However, numerical models with realistic thunderstorm turbulence have not been performed, and the models have generally excluded the vertical column stretching that is crucial in atmospheres. Here, I present numerical simulations using the shallow-water equations, which are the simplest atmospheric equations that allow full vertical column stretching to occur. The model includes a realistic parameterization of thunderstorm turbulence: the thunderstorms are sporadic, isolated, and transport mass into the weather layer. In the simulations, the thunderstorms cause the production of numerous vortices (primarily anticyclones) with speeds up to about 100 m/sec, consistent with Jupiter and Saturn. However, the jets that form are much too broad, and the mid-latitudes become dominated by enormous vortices rather than jets. These effects apparently result from the column stretching (finite deformation radius) in the shallow-water equations, which can cause the suppression of the beta effect that is crucial for jet production. I will discuss the implications for Jupiter and Saturn.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 5210 Planetary atmospheres, clouds, and hazes (0343)
DE: 6220 Jupiter
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: Fall Meeting 2005