Recorded presentation14D.4
Exploring the diurnal cycle in rainfall using idealized cloud resolving model studies
Larissa E. Back, University of Wisconsin- Madison, Madison, WI
The diurnal cycle in tropical rainfall is a major mode of variability in our climate system, which we presently have an incomplete understanding of. Observations show that statistically, the diurnal rainfall maximum over land occurs 4-5 hours after local noon. In contrast, in large-scale numerical models, deep convection often erupts earlier in the day. It has been suggested that this is due the incorrect representation of moisture-convection relationships in numerical models.
In this study, I examine the results of simple experiments using a cloud resolving model, the System for Atmospheric Modeling (SAM), which are designed to study the diurnal cycle of deep convection over a tropical island in a highly idealized setting. Results show that including interactions with the ``large-scale dynamics'' that are often externally specified in cloud resolving model studies is crucial to reproducing the correct timing of the diurnal precipitation maximum. I discuss the reason for this result and the implications for how moisture is modulating deep convection in this context.
Session 14D, Convection III
Thursday, 13 May 2010, 1:15 PM-3:00 PM, Tucson Salon A-C
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