HR: 0800h
AN: A21B-0742    [Abstracts]
TI: Cloud-Radiative Interactions With Upper Tropospheric Circulations
AU: * Boos, W R
EM: billboos@mit.edu
AF: Program in Atmospheres, Oceans, and Climate, Massachusetts Institute of Technology, 54-1611, 77 Massachusetts Ave., Cambridge, MA 02139 United States
AU: Bony, S
AF: Laboratoire de Meteorologie Dynamique, Institut Pierre-Simon Laplace, CNRS, LMD/IPSL, UPMC, case courrier 99, 4 place Jussieu, Paris, 75252 France
AB: A mechanism for the interaction of cloud-radiative effects with large-scale upper tropospheric circulations is explored using both idealized numerical models and atmospheric data. In a zonally-symmetric model of the atmosphere containing representations of moist convection, radiation, and partial cloudiness, overturning circulations were induced by the vertical dipoles of radiative heating which exist between the bases and tops of upper tropospheric clouds. Such circulations preferentially enhanced the dynamical variability of the upper troposphere on timescales of several days, as compared to longer seasonal timescales. Vertical velocities from reanalyzed atmospheric data exhibited a similar proportional enhancement with height of such higher frequency variability. Correlations between humidity, vertical velocity, and indicators of cloudiness for this reanalyzed data set are also discussed. All of these results are compared with integrations of a three-dimensional general circulation model in which the radiative heating profiles were vertically smoothed in the upper troposphere, thereby eliminating the vertical heating dipole collocated with high-level clouds.
DE: 3359 Radiative processes
DE: 3374 Tropical meteorology
DE: 3300 METEOROLOGY AND ATMOSPHERIC DYNAMICS
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting