Paleoclimate simulations of tropical cyclones in a 36-km tropical channel model of the Last Glacial Maximum

Abstract:

Climate change and tropical cyclone (TC) climatology has been the subject of a rapidly growing body of work, and both the observational record and general circulation models’ (GCM) prediction of the next century’s climate have been studied to learn how TC frequency, tracks, and intensity may change with the evolving large-scale environment. We have adpoted many of the techniques successfully used to study TC climatology in a future climate for analysis of the Last Glacial Maximum (LGM, 21,000 ka). By focusing on a climate state that is very different from either the present day or from projected future anthropogenic warming scenarios, this approach provides new insights into the links between TCs and the large-scale environmental factors that control them, and provides an improved foundation for studies of how tropical cyclones have impacted the geological record. We have used the Weather Research and Forecasting (WRF) model in a 36-km tropical channel configuration to dynamically downscale output from the Community Climate System Model, version 4 (CCSM4), simulations of the Last Glacial Maximum and 20^th century, both from phase 5 of the Coupled Model Intercomparison Project (CMIP5). We have downscaled 10 years of output for the LGM and for the 20^th century and developed a climatology of the downscaled tropical cyclones for each. Here we show the changes in simulated TC tracks and intensity between LGM and the 20^th century and link the changes in the downscaled tropical cyclones to large-scale climate indices and vortex tracking from the GCM output.