Multi-model projection of tropical cyclone genesis frequency over the Western North Pacific: CMIP5 results

Abstract

Analyzing outputs of seven climate models participating in the fifth phase of the Climate Model Intercomparison Project, this study performs multi-model projection of tropical cyclone (TC) genesis frequency over the Western North Pacific basin, with an emphasis on the spatial contrast. By evaluating reproducibility of the spatio-temporal distribution of the genesis frequency, we select five models to perform the multi-model projection. All five models and multi-model ensemble project eastward shift of the Main Development Region (MDR) of TCs located around the Philippines. This is probably caused by changes in dynamical environmental conditions such as lower-tropospheric relative vorticity and vertical shear of horizontal wind. Projected changes in the activity of tropical depression-type disturbances, which are candidates for seeds of TCs, may also contribute to the eastward shift. These projections are basically consistent with earlier results that Yokoi and Takayabu (2009) obtained from outputs of a previous generation of climate model experiments. In addition, this study projects increases in the genesis frequency over a region east of Taiwan and the South China Sea, which are inconsistent with Yokoi and Takayabu (2009).