1981—2021年雅鲁藏布江中下游极端气温事件变化特征

Characteristics of Variation in Extreme Temperature Events in the Middle and Lower Reaches of the Yarlung Zangbo River from Year 1981 to 2021

雅鲁藏布江流域地处青藏高原,其生态环境脆弱,易受到极端气候事件影响,分析本流域极端气温事件有利于合理开发资源,并为气象灾害防御工作提供理论借鉴。根据1981—2021年雅鲁藏布江中下游流域14个气象站逐日平均气温、日最高气温、日最低气温资料,采用线性倾向估计、反距离权重法、Mann-Kendall突变检测等方法分析了近41年雅鲁藏布江中下游极端气温事件时空变化特征。结果表明:(1)极端最高气温、暖昼日数、暖夜日数和冷昼日数均呈自东向西递减的空间分布规律,而极端最低气温、冷夜日数、霜冻日数、结冰日数则相反。(2)极端最高气温和极端最低气温表现为微弱的上升趋势,增幅分别为0.2℃·(10a)^(-1)、0.3℃·(10a)^(-1);暖昼日数和暖夜日数分别以4.7 d·(10a)^(-1)、10.7 d·(10a)^(-1)的速度显著增加;冷昼日数、冷夜日数、霜冻日数和结冰日数均趋于减少,减幅依次为5.9 d·(10a)^(-1)、4.9 d·(10a)^(-1)、5.8 d·(10a)^(-1)、0.5 d·(10a)^(-1)。(3)在时间转折上,除极端最高气温和暖昼日数未发生气候突变外,其余要素均发生了突变,其中极端最低气温、暖夜日数分别在1985年、2011年发生了由偏低(少)向偏高(多)的突变,此外,冷昼日数、冷夜日数、霜冻日数和结冰日数分别在1997年、2003年、1996年、1993年发生了由多变少的突变。

The temporal and spatial variation characteristics of extreme temperature events in the middle and lower reaches of the Yarlung Zangbo River were analyzed based on the 41 years(from year 1981 to 2021) daily average maximum and minimum temperature data of 14 weather stations,by using linear propensity estimation,inverse distance weight method and Mann-Kendall mutation detection method.The results showed that:(1) The extreme daily maximum temperature,number of warm days,warm nights and cool days show a decreasing distribution pattern from east to west,while the extreme daily minimum temperature,number of cold nights,frost days,and freezing days are opposite.(2) TXx and TNn showed a slightly increasing trend with amplitudes of 0.2℃·(10a)^(-1) and 0.3℃·(10a)^(-1),respectively,TX90 and TN90 increase significantly with the rate of 4.7d·(10a)^(-1) and10.7d·(10a)^(-1),respectively,and TX10,TN10,FD and ID tend to decrease with decreasing amplitudes of 5.9 d·(10a)^(-1),4.9 d·(10a)^(-1),5.8 d·(10a)^(-1) and 0.5 d·(10a)^(-1),respectively.(3)Regarding the turning point of time,except for TXx and TX90,the rest of the climate elements have undergone abrupt changes and among them TNn and TN90 experienced an abrupt change from low(less) to high(more) in year 1985 and 2011,respectively,and TX10,TN10,FD and ID experienced an abrupt change from more to less in year 1997,2003,1996 and 1993,respectively.