The Spatial Variation Characteristics and Mechanism of Landing Tropical Cyclones in China

Abstract

Based on the tropical cyclone (TC) data from the United States Joint Typhoon Center, this paper analyzes the spatial variation characteristics and possible mechanism of the TC that landed in China during the 65 years from 1951 to 2015. The conclusions are as follows. (1) The TC transformation location moves to southeast in El Niño years, and shifts to northeast in La Niña years. (2) In El Niño years, the frequency of TC affecting the coast of Mainland China is relatively low, while the frequency of TCs affecting Japan is increasing. In La Niña years, the frequency of TCs affecting Japan and the surrounding waters, the Yellow Sea, the Bohai Sea and the South China Sea increased, while that of Taiwan province decreased. (3) The changes in the local circulation in the Northwest Pacific increased the sea temperature, increased convection, increased relative humidity in the middle layer, weakened vertical wind shear, increased low-level vorticity, and increased high-level divergence in the southeastern part of the Northwest Pacific during the El Niño year. The large-scale circulation adjustments provided favorable background conditions for the southeast movement of the TC generating position. The southeast movement of the spawning location makes the landing TC activities have a longer moving distance and thus increases the life history. In La Niña years, the subtropical high weakened and moved eastward. This environment is conducive to generating more TCs to land in China in the La Niña year.