Tropical cyclone genesis factors in paleoclimate simulations
Over the last twenty years, a pioneering group of geomorphologists has developed processes for extracting information about prehistoric, landfalling hurricanes back through the last several millennia by studying sedimentary over-wash deposits in geologic cores. They have found active periods interspersed among long intervals with little or no trace of significant activity, which raises interesting questions about how the conditions supporting tropical cyclones change over time. The factors that make an environment favorable for tropical cyclones to form have been studied and investigated over the course of the last 60 years, with much of the important work done here at Colorado State. General circulation models, while too coarse to properly form and resolve individual tropical cyclones, are designed to forecast the large-scale properties of the atmosphere crucial to their formation. Our group has used simulations of paleoclimates to investigate how these factors respond to changes in atmospheric composition, orbital geometry, volcanoes, and solar cycles. In this talk I will show how these large-scale genesis factors differed at significant intervals of the last 20,000 years--- from the height of the last glacial maximum through the Holocene epoch and last millennium.