HR: 11:00h
AN: A12A-03    [Abstracts]
TI: The Gravity Wave Response to Observed Fine-Scale Latent Heating Structure
AU: * Alexander, M
EM: alexand@cora.nwra.com
AF: NorthWest Research Associates, Colorado Research Associates Div 3380 Mitchell Lane, Boulder, CO 80301 United States
AB: Gravity waves generated by convection are important to the global circulation in the stratosphere and above, and may also play a role in initiation of subsequent remote convective events. We are studying wave emission from convective rain cells by forcing a mesoscale cloud resolving model with observed precipitation patterns from radar. The wave forcing is known to be sensitive to the details of the latent heating, and the radar data provide the most realistic possible description of these details. Our model has been previously validated with other observations from the Darwin Area Wave Experiment (DAWEX). The waves generated in our model are analyzed and compared to linear models of wave generation and wave propagation. Parameterizations of convectively generated waves are based on linear models of heat sources in different shear environments. We compare the mesoscale model to the Beres et al. (2004) source parameterization for convectively generated waves. We find descrepancies that suggest improvements to the parameterization, namely inclusion of a forcing term due to the so-called obstacle effect, where the heating centers act as obstacle to shear flow in the upper troposphere. We also find interesting wave reflection effects in the upper troposphere which are less significant to the momentum budget and parameterization problem, but which lead to trapped waves that may be relavent to remote convective initiation. We study the wave reflection by comparison of the mesoscale model to linear wave propagation and tunneling models that suggest more than half of the wave energy is trapped in the troposphere at certain wave phase speeds.
DE: 3300 METEOROLOGY AND ATMOSPHERIC DYNAMICS
DE: 3329 Mesoscale meteorology
DE: 3354 Precipitation (1854)
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly