Processes Linking Easterly Waves and the North American Monsoon System

University Of Arizona, Tucson AZ

Investigators

Abstract

This study will address variability in the North American monsoon associated with easterly waves and tropical disturbances. More than 25 years of observations and short-term forecasts from a regional model will be used. Previous work suggests that easterly waves and tropical storms have a significant influence on the location and amount of precipitation within the North American monsoon region. Several key processes of the North American monsoon are not well represented in global or regional models, making it difficult to establish the physical mechanisms linking monsoon synoptic variability with more slowly varying processes associated with the tropical ocean-atmosphere system. The investigators will use short-term Weather Research and Forecasting (WRF) model simulations to determine how easterly waves and tropical disturbances affect monsoon precipitation. The model will be run at high enough resolution to avoid the use of convective parameterizations in the core monsoon region, thus eliminating one of the primary contributors to errors in regional model simulations of monsoon precipitation. This work has the potential for improving monsoon forecasts and it addresses the scientific objectives of the North American Monsoon Experiment (NAME), a field campaign that took place in the summer of 2004 with the goals of determining the sources and limits of predictability of monsoon precipitation. This study builds on the work of the NAME community, including that of two of the principal investigators (PIs), as well as recent work on easterly waves including that of the third PI. The modeling aspect of the proposed study takes advantage of the University of Arizona WRF model, the model providing the highest resolution forecasts of the Southwest, and it will contribute to the establishment of a regional atmospheric model for emerging research applications and societal needs in the Southwest region. Broader impacts of this project include potential improvements in monsoon forecasts that can help local governments in the Southwest to respond to flooding and weather-related hazards and to manage water resources for their growing populations. The project will contribute to multidisciplinary interactions on the University of Arizona campus, including the development of a new hydrometeorology program; it will support undergraduate research in the sciences and provide students with examples of the achievements of Hispanic and women scientists in a physical science and mentoring from such scientists. A graduate student and one or more undergraduate research projects will be supported.