Future change of East Asian extratropical cyclones in CMIP5 models

Abstract

Extratropical cyclones (ETCs) in East Asia are detected and tracked by applying an automated tracking algorithm to the 850-hPa relative vorticity field. The ETC statistics during the period of 1979-2014 show that East Asian ETCs primarily organize over Mongolia, South China, and the Kuroshio Currents. Both Mongolia and South China ETCs form on the leeward side of the mountains in these regions. Kuroshio ETCs develop in regions with a sharp SST gradient. The response of East Asian ETCs to anthropogenic forcing is also studied through a comparison of historical simulations and a RCP 8.5 scenario of CMIP5 models. Historical simulations reproduce spatial distribution and seasonality of ETC frequency, genesis, intensity, and growing rate qualitatively well. But, ETC genesis in the South China region is underestimated in quantity. The frequency and intensity of ETCs decrease in future scenarios particularly over the western North Pacific due to diminished cyclogenesis downstream of the Tibetan plateau and across the Kuroshio Current and due to vertical wind shear and static stability changes in the warming climate.