Tropical Atmosphere/Ocean Variability in the Boreal Summer and Its Relationship with Atlantic Hurricanes

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

The Atlantic Meridional Mode (AMM) is the leading mode of coupled variability in the Atlantic, and represents a distinct coupled pattern of sea surface temperature and atmospheric fields that emerges through a broad spectrum of external forcing mechanisms. Previous work has shown that the AMM may provide a dynamical explanation for the observed coherence between a number of regional atmospheric and oceanic conditions that are relevant for tropical cyclone formation. This project aims to better understand the cause of AMM variations during boreal summer, with an emphasis on understanding the link between the AMM and tropical cyclone activity. The research will utilize designed experiments using global general circulation models, dynamical analysis of simple coupled models, analysis and interpretation of observational data, and analysis of existing global coupled model simulations of present and future climate. Specifically, this project will address (i) What is the structure of the AMM during boreal summer? (ii) What dynamical processes control the AMM during boreal summer, and the relationship between the AMM and environmental conditions that influence hurricane activity? (iii) What external forcing mechanisms influence the AMM during boreal summer, and what is the relationship between the Atlantic Multidecadal Oscillation (AMO) and AMM, and (iv) What is the predictability of the AMM, and what processes influence that predictability? Broader impacts of this project include encouraged integration between the disciplines of climate dynamics and tropical cyclone characteristics, training of two graduate students and one post-doctoral researcher, broader dissemination of results in national and international venues, and public availability of real-time data relating to the AMM and to tropical cyclone activity.