中文摘要：

针对近年来中国区域高温热浪日数日趋增加的问题,利用1961—2013年中国区域719个基准站逐日气温数据,并根据持续时间将高温热浪分为弱、中强、强3种等级,对比分析3种不同等级高温热浪发生频次、起始及结束时间的变化特征及区域差异。结果表明：在分析时段,中国区域整体平均高温日数呈现显著的先减后增的变化趋势,转折点为1993年。高温日数变化趋势存在显著区域差异,其中西南、华南地区的高温热浪增速最快,趋势系数均通过95%显著性检验;3种等级高温热浪所发生的区域不同,其中,弱高温热浪主要发生在中国西北、华中地区,强高温热浪主要分布在华南、西南地区,且3种等级的高温热浪发生频次均呈上升趋势。从发生的起始时间看,弱高温热浪开始日期最早,平均开始于每年的7月3日,而中强和强高温热浪开始时间相近,分别为7月13日和7月14日;从区域上来看,3种等级高温热浪均最早在西南爆发,而华中、华东、华南地区爆发最晚。除西南地区外,3种等级高温热浪的起始时间呈提前趋势,而7个区域结束日期的变化趋势存在南北差异：30°N以南地区弱、中强高温热浪结束日期均呈推后趋势,强高温热浪结束日期在30°-35°N地区显著推后,而在北方呈提前趋势。

英文摘要：

Heat wave has become a severe problem over China in recent year. Based on daily air temperature data from 719 meteorological stations in China in the period of 1961-2012, the heat wave events were classified into three levels by duration： weak HW, medium heat wave and strong heat wave. This paper describes the spatial and temporal characteristics among three levels of heat wave over China during the period 1961-2013. The results showed that the number of hot days displayed a weakening trend from the 1960s to the early 1990s, followed by a strengthening trend from the late 1990s up to now. Long-term linear trends in hot days had significant regional differences, for instance, the number of hot days in southwest and southern China growing sharply than other regions; three levels heat wave occurred in different regions that weak heat wave usually occurred in the northwest and middle part of China while strong heat wave mainly happened in the southern part of China. When it came to the first day of heat wave, weak heat wave occurred earliest in China, and it happened around July 3rd while medium heat wave and strong heat wave always started on July 13th and July 14th, respectively. In general, the earliest heat wave was always found in southwest China while the last ones usually occurred in southern part and southwest China. Increasing trend of three levels heat wave were found in the entire country, except for southwest China. The trend of the last day of heat waves showed significant difference between northern and southern part of China. The last day of weak and medium heat wave occurred later in the south China, while strong heat wave happened earlier in north China.