Tropical cyclone frequencies inferred from Gray's yearly genesis parameter: Validation of GCM tropical climates

Abstract

The Gray Yearly Genesis Parameter (YGP) is an empirical diagnostic tool used to infer regions in which necessary (but not sufficient) conditions exist for tropical cyclone development. This parameter is used here as a measure of the implied tropical cyclone frequency and area of occurrence in climate simulations generated by a General Circulation Model (GCM). In a simulation of the current climate, the CSIRO9 GCM shows reasonable agreement with the original Gray climatology. The YGP for a doubled CO 2 simulation is presented.