HR: 1340h
AN: P33A-0238 [Abstracts]
TI: Exchange of Global Mean Angular Momentum Between an Atmosphere and Its Underlying Planet
AU: * Zhu, X
EM: xun.zhu@jhuapl.edu
AF: JHU/APL, 11100 Johns Hopkins Road, Laurel, MD 20723/6099
United States
AU: Strobel, D F
EM: strobel@jhu.edu
AF: JHU, Dept of Earth & Planetary Sci., Baltimore, MD 21218
United States
AU: Flasar, M F
EM: F.M.Flasar@gsfc.nasa.gov
AF: JHU/APL, 11100 Johns Hopkins Road, Laurel, MD 20723/6099
United States
AU: Flasar, M F
EM: F.M.Flasar@gsfc.nasa.gov
AF: NASA/GSFC, NASA/GSFC,Code 693, Greenbelt, MD 20771
United States
AB:
This paper investigates the exchange of global mean angular momentum between an atmosphere and its underlying planet by a
simple model. The model parameterizes four processes that are responsible for zonal mean momentum budget in the atmospheric
boundary layer for a rotating planet: (i) meridional circulation that redistributes the relative angular momentum, (ii)
horizontal diffusion that smoothes the prograde and retrograde winds, (iii) frictional drag that exchanges atmospheric
angular momentum with the underlying planet and (iv) internal redistribution of the zonal mean momentum by wave drags. It is
shown that under a steady state or a long-term average condition, the global relative angular momentum in the boundary layer
vanishes unless there exists a preferred frictional drag for either the prograde or the retrograde zonal wind. We further
show quantitatively that one cannot have either a predominant steady prograde or retrograde wind in a boundary layer of a
planetary atmosphere. The parameter dependences of the global relative angular momentum and the strength of atmospheric
circulation in the boundary layer are derived explicitly and used to explain the observational differences between the
atmospheres of Earth and Venus.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 3319 General circulation (1223)
DE: 3346 Planetary meteorology (5445, 5739)
SC: Planetary Sciences [P]
MN: Fall Meeting 2005