Zhao Lin, Li Xinxin, Zhang Zhijiang, Yuan Moxi, Sun Shao, Qu Sai, Hou Mengjie, Lu Dan, Zhou Yajuan, Lin Aiwen
School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China.
School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China.
Sci Total Environ. 2023 May 20;874:162366. doi: 10.1016/j.scitotenv.2023.162366. Epub 2023 Feb 26.
Compound drought and heatwave events (CDHEs) are more devastating than single drought or heatwave events and have gained widespread attention. However, previous studies have not investigated the impacts of the precipitation attenuation effect (PAE) (i.e., the effect of previous precipitation on the dryness and wetness of the current system is attenuated) and event merging (EM) (i.e., merging two CDHEs with short intervals into a single event). Moreover, few studies have assessed short-term CDHEs within monthly scales and their variation characteristics under different background temperatures. Here we propose a novel framework for assessing CDHEs on a daily scale and considering the PAE and EM. We applied this framework to mainland China and investigated the spatiotemporal variation of the CDHE indicators (spatial extent (CDHE), frequency (CDHE), duration (CHHE), and severity (CDHE)) from 1968 to 2019. The results suggested that ignoring the PAE and EM led to significant changes in the spatial distribution and magnitude of the CDHE indicators. Daily-scale assessments allowed for monitoring the detailed evolution of CDHEs and facilitated the timely development of mitigation measures. Mainland China experienced frequent CDHEs from 1968 to 2019 (except for the southwestern part of Northwest China (NWC) and the western part of Southwest China (SWC)), whereas, hotspot areas of CDHE and CDHE had a patchy distribution in different geographical subregions. The CDHE indicators were higher in the warmer 1994-2019 period than in the colder 1968-1993 period, but the rate of increase of the indicators was lower or there was a downward trend. Overall, CDHEs in mainland China have been in a state of remarkable continuous strengthening over the past half a century. This study provides a new quantitative analysis approach for CDHEs.
复合型干旱和热浪事件（CDHEs）比单一的干旱或热浪事件更具破坏性，已受到广泛关注。然而，以往的研究尚未考察降水衰减效应（PAE）（即前期降水对当前系统干湿状况的影响减弱）和事件合并（EM）（即将间隔较短的两次CDHEs合并为一次事件）的影响。此外，很少有研究评估月度尺度内的短期CDHEs及其在不同背景温度下的变化特征。在此，我们提出了一个在日尺度上评估CDHEs并考虑PAE和EM的新框架。我们将该框架应用于中国大陆，研究了1968年至2019年CDHE指标（空间范围（CDHE）、频率（CDHE）、持续时间（CHHE）和强度（CDHE））的时空变化。结果表明，忽略PAE和EM会导致CDHE指标的空间分布和量级发生显著变化。日尺度评估能够监测CDHEs的详细演变情况，并有助于及时制定缓解措施。1968年至2019年期间，中国大陆频繁发生CDHEs（中国西北（NWC）西南部和中国西南（SWC）西部除外），而CDHE和CDHE的热点区域在不同地理子区域呈零散分布。CDHE指标在较温暖的1994 - 2019年期间高于较寒冷的1968 - 1993年期间，但指标的增长率较低或呈下降趋势。总体而言，在过去半个世纪里，中国大陆的CDHEs一直处于显著的持续增强状态。本研究为CDHEs提供了一种新的定量分析方法。
