Background,aim,and scope The Northern Xinjiang is one of the most important industrial and agricultural production area in northwest China,which belongs to arid and semi-arid regions. However,as a result of extremely fragile ecological environment and sensitive to climate change,lots of researchers focus on its environment change. The occurrence of extreme weather events showed more frequency and intensity in the background of global climate change,the loss of life and property of people will be greater than before. But the existing researches on extreme climate change in this region mainly focus on the temporal and spatial variation characteristics of extreme weather events,less researches on the influence factors of extreme weather events especially the influence of atmospheric circulation index,that disadvantage to accurately predict the occurrence of extreme weather events. Materials and methods Based on meteorological stations in Northern Xinjiang,1960 — 2012 calendar year,daily air temperature data downloaded from National Climate Center,China Meteorological Administration,and atmospheric circulation index (including Arctic Oscillation index,North Atlantic Oscillation index,El Ni?o and the Southern Oscillation) from National Oceanic and Atmospheric Administration Earth System Research Laboratory—Physical Sciences Division (NOAA-ESRL: PSD),using linear regression analysis,moving average,principal component analysis,correlation analysis and Inverse Distance Weighted to analyze the spatiotemporal variation characteristics of extreme temperature changes in Northern Xinjiang and investigate the relationship between the extreme temperature index and atmospheric circulation index. Results The results showed that annual mean minimum temperature and annual mean maximum temperature displayed significant positive trend at rate of 0.49℃?(10a)?1,0.22℃?(10a)?1,respectively,while diurnal temperature range displayed negative trend at rates of 0.27℃?(10a)?1; indices of warm temperature extremes growing season length,warm nights,highest of the daily minimum temperature and tropical nights displayed significant positive trend at rate of 2.52 d?(10a)?1,3.18℃?(10a)?1,0.45℃?(10a)?1 and 1.14 d?(10a)?1,respectively; while warm days,summer days and highest of the daily maximum temperature showed non-significant positive trend at rate of 1.24 d?(10a)?1,1.58 d?(10a)?1 and 0.09℃?(10a)?1,respectively. The cold temperature extremes frost days,ice days,cold nights and cold days displayed negative trend at rate of ?3.70 d?(10a)?1,?1.46 d?(10a)?1,?3.41 d?(10a)?1 and ?1.26 d?(10a)?1,while lowest temperature of the daily minimum and lowest temperature of the daily maximum showed non-significant positive trend at rate of 0.57℃?(10a)?1 and 0.26℃?(10a)?1. The results of Inverse Distance Weighted method showed,the indices of diurnal temperature range,all the cold extremes and mostly warm extremes have larger trend magnitudes in regional of southeastern of Altai Mountains and Yili Valley area. Discussion The trend magnitudes in cold extremes (cold nights,lowest temperature of the daily maximum,lowest temperature of the daily minimum) are obviously larger than those of warm extremes (warm nights,highest temperature of the daily maximum and highest temperature of the daily minimum),and this characteristic are most obviously in regional of piedmont and valley area. Arctic Oscillation index (AO) has the strongest correlated with temperature extreme,in particular,the correlated with cold temperature extremes are obviously. North Atlantic Oscillation index (NAO) has significant positive correlated with lowest temperature of the daily minimum and highest temperature of the daily minimum while displayed non-significant correlated with warm temperature extremes. El Ni?o and the Southern Oscillation (ENSO) has non-significant correlated with each extreme temperature. Conclusions The occurrence of extreme cold indices have a more magnitude trend than warm indices,indicated the daily low temperature have a trend of increasing,and the occurrence of warm winter will be more frequency. Correlation analysis indicated the occurrence of extreme weather events especially extreme cold indices are mainly affected by Arctic Oscillation index,followed by North Atlantic Oscillation index,while the El Ni?o and the Southern Oscillation has little effect to the extreme weather events in Northern Xinjiang. Recommendations and perspectives Analysis on the variation characteristics of extreme weather events in Northern Xinjiang,not only provide reference for development of industries and agriculture in this region,can contribute to have a deep understanding the forecast of the future occurrence of extreme weather events and its response to atmospheric circulation index in Northern Xinjiang.%根据北疆地区1960—2012年31个气象站点的逐日最高气温和最低气温资料,采用线性趋势分析、主成分分析和反距离加权等方法对该地区的年平均最高气温、年平均最低气温和14个极端气温指数的时空变化特征进行了研究,并探讨了各极端气温指数与北极涛动指数、北大西洋涛动指数和厄尔尼诺-南方涛动之间的关系.研究表明:(1)近53年来,北疆地区年平均最低气温、年平均最高气温分别以0.49℃ ?(10a)?1、0.22℃ ?(10a)?1的年际倾向率呈显著的上升趋势;气温日较差以0.27℃ ?(10a)?1的年际倾向率呈显著下降趋势.极端暖指数除暖昼日数、夏日日数和极端最高气温均表现为不显著的上升趋势外,其他暖指数均呈显著上升趋势;极端冷指数中除极端最低气温、日最高气温的极小值呈上升趋势外,其他冷指数均呈减小趋势;在空间变化上各极端气温指数均表现为在阿尔泰山东南部地区和伊犁河谷地区变化幅度较大,其他地区变化较小.(2)冷指数(冷夜、日最高气温的极小值、极端最低气温)的增温幅度明显大于部分暖指数(暖夜、日最低气温极大值、极端最高气温),这一变化特征在山麓、山谷等地区表现最为明显,而在这一地区夜指数(暖夜、冷夜)的变暖幅度也明显大于昼指数(暖昼、冷昼).(3)极端气温指数与大气环流指数相关性分析表明,三种大气环流指数中北极涛动指数对北疆地区极端气温的影响最为明显,其次是北大西洋涛动指数,且这两种大气环流指数对研究区极端气温冷指数的影响较为显著,而厄尔尼诺-南方涛动对研究区极端气温影响较小.
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