Collaborative Research: Tropical Cyclones in a Warming Climate: Lessons from Model Simulations of the Last Glacial Maximum and Holocene

DESCRIPTION: This collaborative project uses numerical simulations to study the likely behavior of tropical cyclones (TCs, which include Atlantic hurricanes, Pacific typhoons, and cycones in the Indian Ocean), at the height of the last ice age (about 21,000 years ago) and during the mid-holocene warm period of about 6,000 years ago. Much attention has been devoted to understanding the impact on TCs of the warming of the world's oceans over recent decades and the likely response of TCs to future global warming. This study seeks to further understanding of the impact of climate change on TCs by looking backward to past climates which are comparably different from today's climate, although in different ways. Four specific questions are addressed: 1) How do the factors that influence tropical cyclone genesis vary under LGM and mid-holocene forcings? 2) Are there significant variations in how different models resolve these large-scale factors? Which changes appear attributable to model variability and which to variations in external forcing? 3) How do the TC-like vortices found in climate models change in LGM and mid-holocene simulations when compared to preindustrial or present-day conditions? 4) How does a higher resolution, regional model's simulation of a paleoclimate environment handle genesis? How do storm counts and track densities vary as the climate forcing changes? The research is based on preliminary results which find evidence that the climate of the last ice age may have been relatively favorable for TC development in some regions, despite the generally colder sea surface temperatures worldwide.

The work has broader impacts in the scientific community as it will inform research into the emerging science of "paleotempestology", the interdisciplinary study of the behavior of TCs and other storms in past climates. The work will also inform efforts to understand the impact of global warming on landfalling TCs including hurricanes along the US coastline. In addition, the work will fund and train a graduate student and a postdoctoral researchers, thereby providing support and training for the next generation of scientists.

OUTCOMES: This project will 1) be one of the first comprehensive analyses of modeled TC genesis and tracks in a paleoclimate period; 2) advance discovery and understanding while promoting teaching and training through the mentoring of a postdoctoral scientist at UNM and a graduate student at Texas A&M. Two publications and one presentation at the 2011 Fall AGU meeting.