渭河流域热浪事件影响下的骤旱评估

Evaluation of flash drought under the impact of heat waves events in the Weihe River Basin

骤发干旱(简称骤旱)是一种以速度快、强度高为特征的极端事件。然而,对热浪影响下的骤旱过程研究相对有限。文章选取渭河流域作为研究区,根据日最高气温和表层土壤含水量识别热浪和骤旱事件;将骤旱事件分为与热浪相遇和未与热浪相遇的骤旱两种类型,通过比较两类骤旱的历时和发展速度等特征,揭示热浪如何影响骤旱过程。分析结果表明,1981—2020年渭河流域的骤旱和热浪事件发生频次显著增加(p<0.1),在与(未与)热浪相遇的骤旱事件的历时和发展速度平均值分别为8.03(9.66)个候(5 d为1候)和25.44(23.78)个分位变化/候,表明在热浪影响下骤旱事件通常会历时缩短,发展速度加快。研究结果可为热浪影响下的骤旱评估和监测提供理论依据。

Flash drought is a type of extreme climate events characterized by fast speed and high intensity.However,researches on the flash drought processed under the impact of heat waves is relatively limited.The article selects the Weihe River Basin as the research area and identifies heat waves and flash drought events based on daily maximum temperature and surface soil moisture content.It divides flash drought events into two categories,i.e.,those that encounter heat waves and those that do not.By comparing the duration and development speed of the two categories of flash droughts,the article reveals how heat waves affect the process of flash drought.The analysis result shows that the frequency of flash drought and heat waves events in the Weihe River Basin significantly increased from 1981 to 2020(p0.1).The average duration and development speed of flash drought events that encountered(didn't encounter)heat waves were 8.03(9.66)pentads(5 days for 1 pentad)and 25.44(23.78)percentile change/pentad,indicating the duration of flash drought events is shortened and their development speed accelerates impacted by heat waves.The results can provide theoretical basis for the assessment and monitoring of flash drought under the influence of heat waves.