1961—2018年淮河流域热浪事件时空变化特征

Spatial-temporal Variations of Heat Waves in the Huaihe River Basin from 1961 to 2018

利用淮河流域1961—2018年逐日最高气温与平均气温格点数据,在对基于绝对阈值和相对阈值的热浪事件识别方法进行改进的基础上,分析了逐年的热浪强度、烈度、频次、最长历时等时空变化特征。结果表明,淮河流域基于固定气温阈值的绝对热浪(>35℃)的多年平均强度为10.27℃、烈度为1.82℃,频次为1.3次;基于热浪指数的相对热浪多年平均强度为2.27、烈度为0.63,频次为1.0次。空间分布上,绝对热浪多发于流域西部除边缘山地的内陆地区(支流沙颖河流域),相对热浪多发于流域西南地区(淮河干流中上游),总体上流域东北部丘陵地区及东南近海地区的绝对、相对热浪均较弱(少);时间变化上,淮河流域的热浪事件具有显著的趋势性突变,在20世纪60年代初至80年代早期(约1982—1985年)呈减弱(少)趋势,此后呈增强(多)趋势。

Using the daily gridded temperature data during 1961 to 2018,the temporal and spatial characteristics of the annual heat wave severity,frequency,intensity and the longest heatwave duration in the Huaihe River Basin were analyzed with the improved method of heatwave identification based on both absolute and relative thresholds.Results show that the multi-year average magnitude of the absolute heat waves is 10.27℃,severity1.82℃,and frequency 1.3;While the multi-year average magnitude of the relative heat waves is 2.27(in terms of HWMId),severity 0.63(in terms of HWMId),and frequency 1.0.Absolute heat waves have a similar spatial distribution as the maximum daily temperature during June to September,occurring more in the west parts of the basin(especially over the major tributary,Shaying River)except the mountains at the edges,whereas relative heat waves occur more in the southwest parts(especially over the middle to upper Huaihe River).Overall,there is less absolute and relative heat waves in northeastern hilly areas and southeast coast regions.Both absolute and relative heat waves in the Huaihe River Basin showed a significant break of temporal trend,decreasing from the early 1960 s to the early 1980 s(1982-1985)and increasing from the early 1980 s to the end of the 2010 s.