87th AMS Annual Meeting

Wednesday, 17 January 2007: 10:45 AM
The diurnal cycle of warm season rainfall and its relationship to the genesis and propagation of mesoscale events. (Invited)
206B (Henry B. Gonzalez Convention Center)
R. E. Carbone, NCAR, Boulder, CO; and C. C. Chen, T. D. Keenan, A. G. Laing, V. Levizzani, A. J. Pereira, and J. D. Tuttle
By means of satellite and radar data, we have examined the occurrence of warm season rainfall over the United States, Mexico, China, Australia, Africa, Europe and Brazil. Coherent patterns of convective rainfall are evident on all continents during some seasons. Owing to the existence of preferred excitation regions and the propagation of events, heavy rainfall is often well removed in time and space from local diurnal forcings. It will be shown that up to 70% of seasonal rainfall can be associated with events that are remote from the time and location of diurnal excitation. This effect occurs most frequently in the lee of major cordillera and associated with preferred sea/land breeze regimes.

In this presentation we will discuss the environmental conditions associated with the genesis and evolution of coherent rainfall patterns and the impact this has on the local diurnal cycle of rainfall. It will be shown that the diurnal cycle of rainfall over many continental regions is the combined result of classical local forcings at the mesoscale and the remote (delayed-phase) effect of coherent convective regeneration.

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