中国近60年干旱热浪演变趋势及并发特征分析

Evolution Characteristics and Concurrences of Droughts and Heat Waves in China over the Past Six Decades

利用中国气象站1961—2017年降水、气温等资料,构建周尺度标准化帕尔默干旱指数,采用相对阈值法识别热浪过程,分析干旱和热浪的时空演变规律和并发特征,结果表明:(1)干旱和热浪频发于夏季,二者站次比年序列均呈先减(1995年前)后增的变化趋势。(2)全国大部分地区热浪频次显著增加,东北、华北和云南东部的干旱频次显著增加。热浪频次突变年份主要为20世纪80—90年代,其空间分布与干旱较相似。(3)云南为复合型干旱热浪高发区,其次为东北、华北、广西和广东沿海,长江流域和新疆西北部的复合事件最少。(4)全国复合事件中约65%的热浪爆发于旱情开始及发展阶段,云南和长江中下游以南的热浪则出现在旱情恢复阶段。(5)除淮河流域和长江中下游外,复合型干旱热浪呈极显著增加趋势。研究成果可为应对极端天气气候事件和制定适应策略提供科学参考。

Using precipitation and temperature observations from national meteorological stations in China during 1961-2017,the weekly standardized Palmer drought severity index was proposed,and heat waves were recognized by using the relative high temperature threshold method.On this basis,the spatiotemporal evolution features of droughts and heat waves,as well as their concurrences were analyzed.Results reveal that:1)droughts and heat waves occurred frequently in summer.The annual series of the percentage of meteorological stations under droughts and heat waves both indicated a downward tendency before 1995,and an upward tendency afterwards.2)Heat waves took place much more frequently at most stations,and so did drought events in northeast and north China and east Yunnan Province.The freqency of heat waves changed abruptly in the 1980s and 1990s.Such changes presented a similar spatial pattern with droughts.3)Yunnan suffered the most concurrent droughts and heat waves,followed by the northeastern region,the northern region,and coastal areas of Guangxi and Guangdong.In contrast,the Changjiang River basin and northern parts of Xinjiang experienced least concurrent events.4)Among concurrent events,approximately 65%of heat waves occurred in the onset-development stage of droughts,whereas for Yunnan and southern parts of the Changjiang River basin,heat waves mostly occurred in the recovery stage of droughts.5)Except for the Huaihe River basin and the middle and lower reaches of the Changjiang River,concurrent droughts and heat waves significantly increased for the majority of China.