Intermodel Variability in Tropical Cyclones Downscaled from Paleoclimate Simulations

We analyze the tracks, intensity distribution, and other properties of the climatology of storms statistically downscaled from several simulations of the Last Glacial Maximum (LGM) and Mid-Holocene (MH). The Coupled Hurricane Intensity Prediction System (CHIPS) is used to simulate tropical cyclones utilizing data from four members of the Paleoclimate Modelling Intercomparision Project Phase III (PMIP3). Results from the majority of models depict a lower frequency of tropical cyclones both in the LGM and in the Mid-Holocene compared to the preindustrial era or 20^th century controls, but individual models produce more. Our emphasis here is on understanding the sources of this inter-model variability, and we compare changes in large-scale tropical cyclone genesis factors to differences in global and regional circulations between models. Spatial distributions of downscaled tropical cyclones are also compared to tropical cyclone proxies from the geologic past. This analysis provides insight on how tropical cyclones may have behaved during the colder LGM and under different seasonal forcing during the Mid-Holocene. These results and methods, in conjunction with other studies, can be applied to projections of the response of tropical cyclones to anthropogenic climate change.