34th Conference on Radar Meteorology


Investigation of microphysical processes occurring in convection during NAME

Angela K. Rowe, Colorado State University, Fort Collins, CO; and S. A. Rutledge

The onset of the North American Monsoon (NAM) during mid to late June is characterized by an abrupt transition from hot, dry weather to relatively cooler and wetter conditions in the semi-arid regions of southwestern U.S. and western Mexico. The predictability of warm-season rainfall in this core NAM region is limited by the lack of understanding of the structure, kinematics, and evolution of precipitation features and complicated by the presence of the Sierra Madre Occidental (SMO). Previous results from the North American Monsoon Experiment (NAME) have documented a pronounced elevation-dependent diurnal cycle in rainfall intensity and frequency, but questions remain about the microphysical processes responsible for these observed trends. In particular, the presence of significant ice mass in NAME convection is hypothesized to play a role in rainfall production through riming and subsequent melting of graupel, for example; however, the extent of which ice-based processes contribute to rainfall needs to be examined. Information about hydrometeor type, concentration, and location available from NCAR's S-band polarimetric radar (S-Pol) provides a means to evaluate the relative importance of ice-based versus warm-rain microphysics. Several case studies, encompassing a range of topographical elevations and degrees of organization, are presented to investigate potential differences in hydrometeor characteristics in NAME convection.

Poster Session 2, Precipitation and Cloud Microphysics
Monday, 5 October 2009, 1:30 PM-3:30 PM, President's Ballroom

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