A Modeling and Observational Study of South American Cold Air Damming and Frontogenesis East of the Andes

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9522173 Bosart and Knight Under this award, Drs. Bosart and Knight will conduct an observational and modeling study of South American cold air outbreaks and the role that the Andes Mountains play in the modulation and control of these events. As part of this study, the PI s will examine how the presence of the Andes barrier affects the processes of synoptic and mesoscale cyclogenesis, anticyclogenesis, and frontogenesis. Unlike the major mountain barriers of North America or southeastern Australia, the distance, with latitude, between the Andes and the east coast of the continent varies almost linearly. This may allow the PIs to separate orographic and coastal effects on the above processes. The results of these studies is likely to provide important insights for better understanding cold air outbreaks in other parts of the world, including over the U.S. The observational portion of the study will consist of analyses of composite climatologies of cold air outbreaks over South America and detailed studies of individual cases, using primarily the gridded data sets being produced by operational centers as part of the reanalysis effort. The numerical simulations will be done with the NCAR mesoscale model (MM5). ***