The relationship of frequent tropical cyclone activities over the western North Pacific and hot summer days in central-eastern China

Yao Ha,Xiu-Qun Yang,Zhong Zhong,Yuan Sun,Xian Chen

doi:10.1007/s00704-019-02908-7

Abstract

Tropical cyclones (TCs) formed over the western North Pacific (WNP) often make landfalls over East Asia and Southeast Asia, causing strong winds and torrential rain in the coastal countries. However, they also bring cool weather on hot summer days and mitigate drought impacts. The present study demonstrates that TC activities over the WNP can strongly modulate extreme summer weather events in eastern mainland China, i.e., frequent TC activities would indirectly lead to more hot days in central-eastern China along the lower and middle reaches of Yangtze River, besides compensating the decreasing of hot days induced by the direct impact of TCs. Such indirect impact is largely determined by the feedback effect of TCs on pressure system, especially on the western Pacific subtropical high, resulting in an abnormal anticyclonic circulation band that dominates a large area from central-eastern China to the Pacific Ocean to the east of Japan in the middle and lower troposphere.

Highlights

Tropical cyclones (TCs) over the western North Pacific (WNP) are among the most devastating weather events that affect East Asia and Southeast Asia
Whether this is true still remains an unanswered question, since it was found that the influence of TCs may affect heat waves in Southeastern Australia indirectly (Parker et al 2013) and the persistent heat wave periods occurred in South China were related to the sinking motion of upper outflow of TC (Fang and Jian 2011)
Three large TC genesis centers can be found in the WNP, i.e., over the northern South China Sea, over the Pacific Ocean to the east of Philippine and near the Mariana Islands in active TC years

Summary

Introduction

Tropical cyclones (TCs) over the western North Pacific (WNP) are among the most devastating weather events that affect East Asia and Southeast Asia. In the coastal region of southeastern China, it can be more than 500 mm per year, which accounts for 20∼40% of the total annual precipitation there (Ren et al 2006; Zhang et al.2013) Those imply possible fewer hot days in southeastern China in the years when more TCs form over the WNP. Whether this is true still remains an unanswered question, since it was found that the influence of TCs may affect heat waves in Southeastern Australia indirectly (Parker et al 2013) and the persistent heat wave periods occurred in South China were related to the sinking motion of upper outflow of TC (Fang and Jian 2011).

Data and Methods

Composite analysis

Numerical experiment

Conclusions and discussion