内蒙古中北部大(暴)雪的分布及其与东亚冬季风关系

Distribution of Heavy Snow and Its Relation with East Asian Winter Monsoon in North-Central Inner Mongolia

摘要: 利用1970~2012年内蒙古锡林郭勒盟15个地面气象观测站基本资料和常规观测资料，综合分析了锡林郭勒盟地区大(暴)雪时空分布特征，并对比分析了东亚冬季风对锡林郭勒盟地区大(暴)雪及积雪的影响。结果表明：近40年大(暴)雪日数由东南向西北逐渐减少。大雪的日数由20世纪七、八十年代的较平稳变化过渡到近20年的具有明显波动的状态，而暴雪日数波动较小，除了个别年份出现极值和没有出现暴雪的年份以外。大(暴)雪出现在9月至次年5月，3月最多，全年在3月和11月存在两个峰值。在1970~2012年期间，东亚冬季风呈明显的线性减弱趋势，冬季风自20世纪80年代中期开始减弱，内蒙古大雪和积雪日数与东亚冬季风指数存在着明显的反相关关系，而与暴雪日数相关关系不显著，这表明，东亚冬季风减弱是内蒙古中北部地区大雪、积雪增加的原因之一，而与极端降雪事件的关系并不明显。

Abstract: Based on the basic data and conventional observation data of 15 ground meteorological stations in Xilingol League of Inner Mongolia from 1970 to 2012, the spatial and temporal distribution characteristics of heavy snow in Xilingol League area are analyzed comprehensively, and the effects of East Asian Winter Monsoon on heavy snow and snow cover in Xilingol League area are compared and analyzed. The results show that the number of snowstorm days has gradually decreased from south-east to northwest in the past 40 years. The number of days of heavy snow has changed from a relatively stable change in the 1970s and 1980s to a state of obvious fluctuation in the past 20 years, while the number of days of heavy snow fluctuates slightly, except for the extreme values in individual years and the years without heavy snow. Heavy snow occurs from September to May of the following year, with the largest number in March and two peaks in March and November of the whole year. From 1970 to 2012, the East Asian winter monsoon showed an obvious linear weakening trend. The winter monsoon began to weaken in the mid-1980s. There was an obvious inverse correlation between the number of snow days and the East Asian winter monsoon index in Inner Mongolia, but not with the number of snowstorm days. This shows that the weakening of the East Asian winter monsoon is one of the reasons for the increase of heavy snow and snow cover in the north-central Inner Mongolia. First, the relationship with extreme snowfall events is not obvious.