1961—2016年中国天山不同级别降雪事件变化特征分析

Change characteristics of different types of snowfall event in China′s Tianshan Mountains from 1961 to 2016

为了更好地理解降雪对气候变化的响应及机理,利用天山山区及周边49个站点日气象资料,采用参数化降雪判识方案提取降雪序列,以百分位阈值法分级别分析天山山区1961—2016年降雪事件变化特征。结果表明:①天山山区降雪量和降雪频次呈山区大于盆地,北坡大于南坡,自西北向东南递减的分布特征。②过去56年来,天山山区降雪量显著增加,降雪频次微弱增加;各级别降雪量和降雪频次变化趋势表现为:小雪显著减少,中雪变化平稳,大雪和极端降雪显著增加;降雪显著增加区域集中分布于天山北坡中部和伊犁河谷地区,降雪量的增加主要由极端降雪量和频次的增加所致。③年降雪量、大雪降雪量和频次、极端降雪量和频次在20世纪80年代中期发生突变增加,其他级别降雪量和频次无明显突变。④天山山区降雪量和极端降雪量的增加与气温变暖有关。

To better understand the mechanisms and response of snowfall to climate change,daily meteorological data from 49 stations in and around the Tianshan Mountains were used to extract the snowfall sequence with a parametrized snowfall identification scheme.The changing characteristics of different snowfall events in the Tianshan Mountains from 1961 to 2016 were analyzed using the percentile threshold method.The results showed that:①The snowfall was larger and more frequent in the mountain region than that in the basin,snowfall on the northern slopes was greater than that on the southern slopes,and snowfall decreased from northwest to southeast.②In the past 56 years,the snowfall in the Tianshan Mountains has increased significantly and the snowfall frequency has increased slightly.The trends in snowfall amount and snowfall frequency at all types were as follows:light snow decreased significantly,moderate snow had no obvious trend,and heavy snow and extreme snow increased significantly.The regions with significant snowfall changes were concentrated in the central region of the northern Tianshan Mountains and Yili River valley.The increase of snowfall was mainly because of an increase in extreme snowfall and snowfall frequency.③Annual snowfall,heavy snowfall and snowfall frequency,and extreme snowfall and snowfall frequency increased abruptly in the mid-1980s,while the snowfall and snowfall frequency of other types showed no obvious change.④The increases in annual snowfall and extreme snowfall in the Tianshan Mountains were related to warmer temperatures.