Observed changes in heat waves with different severities in China during 1961\u20132015

Wenxin Xie,Qinglong You,Yuqing Zhang,Botao Zhou,Safi Ullah

doi:10.1007/s00704-020-03285-2

Abstract

Heat waves (HWs) exert severe impacts on ecosystem, social economy, and human lives. Thus, changes in HWs under a warming climate have triggered extensive interests. In this study, the authors developed a new method to identify the HW events in China by double thresholds and further classified them into four categories (i.e., mild, moderate, severe, and extreme HWs) according to their magnitudes by using the daily maximum temperature data from 701 observation stations. On this basis, the spatiotemporal features of HWs with different severities in China from 1961 to 2015 were investigated. The results show that the high HW frequency mainly appears in Jianghuai, South China and western Northwest China. Moreover, the high frequencies of moderate, severe, and extreme HWs occur from June to August and reach the peak in July, while the mild HW frequency is compared from May to September. Since the 1960s, the frequencies of the mild, moderate, severe, and extreme HWs in China have increased significantly with rates of 7.5, 4.3, 1.4, and 1.8 events per year, respectively. The increases are the greatest in July for the moderate, severe, and extreme HWs while comparable during May to September for the mild HW. Besides, an interdecadal change is found to occur in the late 1990s. Compared with the former period (1961–1996), the occurrence of the extreme HWs during the latter period (1997–2015) has increased most significantly in eastern Northwest China and North China, while the frequency of the mild HWs increases most significantly in Jianghuai and South China.

Highlights

Heat wave (HW) is considered as a period of consecutive days with anomalous high temperature
It can be clearly observed that the stations with the Heat waves (HWs) frequency higher than 2 events per year are mainly located in Jianghuai (JH), South China (SC), and western Northwest China (WNC)
The HW magnitude is relatively larger in the regions with low HW frequency, for instance, in Yunnan Province located in Southwest China (SWC) and Qinghai Province located in eastern Northwest China (ENC) (Fig. 5b)

Summary

Introduction

Heat wave (HW) is considered as a period of consecutive days with anomalous high temperature. It is revealed that there exists a remarkable increase of high temperature in China in recent decades The indices defined by relative thresholds may overcome this problem, but most of them capture the HW magnitude only by the number of days exceeding the thresholds (Perkins 2015). Only using relative thresholds is hard to distinguish real HWs from normal temperature anomalies in cold regions. Due to this reason, this study attempts to address the characteristics of HWs in different regions of China in a consistent way through constructing a new HW identification by using the relative threshold combined with the absolute threshold. Given that few studies concentrated on the changes in HWs with different severities (i.e., mild, moderate, severe, and extreme) in China, we examine the spatiotemporal features of mild, moderate, severe, and extreme HWs in China during the last decades in order to provide a fruitful picture for climate change adaptation and mitigation

Methods

Results

Conclusion