South and North American Monsoons: Characteristics, Life Cycle, Variability, Modeling, and Prediction

The American monsoons are important components of the global monsoon system. Since the annual precipitation over most of South America is mainly concentrated in the summer monsoon season, the economy, agriculture, water/energy resources and, consequently, the livelihoods of the great majority of population are heavily dependent on the South American monsoon (SAM). On the other hand, the North American monsoon (NAM) is the predominant influence on the boreal summer climate of the Southwestern United States and Northwestern Mexico, providing between 40% and 80% of the total precipitation in this region. This chapter summarizes the weather and climatic aspects of the American monsoons, using observational and modeling studies, with focus on their life cycles, mutual influence, variability on a wide range of temporal scales, extreme events, modeling, and prediction. Ongoing and future projections of climatic changes are also addressed. SAM and NAM are the result of land/atmosphere/ocean coupling and characterized by multi-scale interactions that are not completely known or understood. Many challenges still remain to improve understanding and prediction.