Studies of Convection in the North American Monsoon Experiment (NAME)

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The North American Monsoon Experiment (NAME) was carried out in summer 2004 in northwestern Mexico and the Gulf of California to improve understanding and prediction of the North American Monsoon, or NAM. The NAM is responsible for much of the summer rainfall in the southwestern U.S. Before NAME 2004, little was known about the convective and mesoscale rainfall processes in this region. Under a predecessor award, the Principal Investigator participated in the field phase of NAME. He also was able to obtain initial results from NAME as well as previously studied rain gauge data which indicates that rainfall is more frequent over the higher terrain, but falls at more intense rates along the coastal plain. The Principal Investigator is now poised to conduct detailed investigations of the NAME radar dataset following extensive quality control activities. The intellectual merit of this research includes: Understanding precipitation variability between the high terrain of the Sierra Madre Occidental and the adjacent coastal plain, including how microphysical processes and mesoscale organization may vary between these locations and contribute to this rainfall variability; Understanding how mesoscale organization of convection is coupled to prominent features such as the land-sea breeze circulations, the Gulf of California low-level jet, and forcing on the synoptic scale such as associated with tropical easterly waves. The broader impacts of this research include: Improving physical processes in numerical models aimed at simulating the NAM through comparison to polarimetric-radar based analyses from NAME; Adding to general understanding of orographically-induced rainfall since topography plays such an important role in triggering convection in this region; Improving polarimetric radar-based algorithms for rainfall estimation; Validating and improving satellite microwave-based rainfall algorithms, which have known biases in this region.