HR: 1132h
AN: A42C-07    [Abstracts]
TI: A Test of the Simulation of Tropical Convective Cloudiness by a Cloud-Resolving Model
AU: * Hartmann, D L
EM: dhartm@washington.edu
AF: University of Washington, Department of Atmospheric Sciences Box 351640, Seattle, WA 98195-1640, United States
AB: The distribution of tropical high clouds produced by a doubly periodic three-dimensional cloud-resolving model is compared with satellite observations. The model is forced with steady forcing characteristic of tropical Pacific convective regions, and the model clouds are compared with satellite observations for the same regions. Clouds are divided into categories that represent convective cores, moderately thick anvil clouds and thin high clouds. The statistics of these clouds and their relationship to the precipitation rate are computed in a similar way for the model data and for observations from the MODIS and AMSR instruments on the Aqua Satellite. The model produces a good simulation of the relationship between the precipitation rate and optically thick cold clouds that represent convective cores. The model also does a reasonable job of simulating the abundance of thin cold clouds in the East and West Pacific ITCZ regions. The model produces too little anvil cloud by a factor of about 4, however. The observations show probability density functions for OLR and albedo with maxima that correspond to extended upper level cold clouds, whereas the model does not. The sensitivity to model parameters of the simulation of anvil cloud area per unit of precipitation is explored using a two-dimensional model. A set of cloud physics parameters is found that produces anvil cloud with realistic amounts and sensitivity to the precipitation rate, while preserving the good simulation of thick and thin cloud.
UR: http://www.atmos.washington.edu/~dennis/Papers.html
DE: 3305 Climate change and variability (1616, 1635, 3309, 4215, 4513)
DE: 3310 Clouds and cloud feedbacks
DE: 3354 Precipitation (1854)
DE: 3359 Radiative processes
DE: 3374 Tropical meteorology
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting