Future Decadal Change in Tropical Cyclone Activity over the Western North Pacific

Abstract

Future decadal change in tropical cyclone (TC) activity over the Western North Pacific (WNP) are investigated using four regional climate models(RCMs) participating Coordinated Regional Downscaling Experiment (CORDEX) for East Asia. All RCMs is nested by the HadGEM2-AO under historical and Representative Concentration Pathway (RCP) 8.5 scenarios, and performed at 50km horizontal resolution over the CORDEX-East Asia domain. In the historical run (1980-2005), multi-model ensemble (MME) shows fairly realistic climatology for TC genesis and tracks during TC season (June-November), although there is systemic error in simulating TC activity. In future (2024-2049) projections indicate slight increase in total number of TC genesis (+5%), especially significant increase in TC frequency approaching East Asian coastal regions (+17%). The enhanced TC activity over the East Asian coastal regions are mainly related to vertical wind shear weakened by reduced meridional temperature gradient in the mid-latitude. The future ACE of total TC shows significant increase (+19%) because individual TCs have longer lifetime (+6.6%) and higher maximum wind speed (+4.1%) compared to those in historical run. Intensity analysis of maximum wind speed and minimum sea level pressure indicates increasing intense TC as well as decreasing mild TC in RCP 8.5 future projection. Despite the change in total TC number is not quite large, TC activities prominently increase in the mid-latitude. This can affect future disaster management in East Asia nations.