Downscaling Tropical Cyclones in the Last Glacial Maximum and Mid-Holocene

A study of a regional climate modeling using the Weather Research and Forecasting (WRF) model is being conducted to investigate the behavior of large-scale dynamic and thermodynamic variables that produce a favorable environment for tropical cyclone genesis and growth in different climate states under the Last Glacial Maximum (LGM), mid-Holocene (6ka), and present era. Fundamental questions of the study include: (1) How do the factors that influence tropical cyclone genesis vary under LGM and 6ka forcings?
(2) Are there significant variations in how the different models that contributed to paleoclimate model intercomparison project (PMIP2) resolve these large-scale factors? Which changes appear attributable to model variability and which to variations in external forcing? (3) How does TC-like vortex development in CCSM change in LGM and 6ka simulations when compared to preindustrial or present-day conditions?
(4) How do track densities in CCSM's simulation of the LGM and 6ka differ from those in its simulations of the current climate?
(5) 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? Answering these questions would contribute to understandings of both how tropical cyclones may have varied from the LGM through the Holocene and how the models used to predict anthropogenic changes handle the climatology of tropical cyclone factors in a radically different environment. In particular, a dynamical downscaling approach using the WRF are to estimate changes in hurricane frequency and track density in the Western Pacific and Atlantic oceans for the LGM and mid-Holocene compared to the present day and to compare downscaling results with those derived from the other approaches. The current status of the study with the analyses of the WRF regional climate model outputs from the study as well as preliminary analyses of some of the monthly mean data generated by CCSM paleoclimate runs as part of the PMIP2 will be addressed in detail.