新疆北部牧区雪灾评估指标及其成因分析

Evaluation and Cause Study on the Snow Disasters in Pastoral Areas of Northern Xinjiang

采用阿勒泰地区7个气象观测站1961—2012年最大积雪深度、逐月降水量、逐日气温资料,以及4—9月降水量、≥0℃的积温,同期的雪灾灾情资料及太阳黑子和2007—2012年的牧草产量资料,研究新疆北部牧区雪灾灾情及成因。将该地区雪灾分为特大雪灾年、重雪灾年、中雪灾年、轻雪灾年4类,雪灾综合指标对雪灾具有较高的评价精度;重雪灾年和特大雪灾年主要发生在21世纪初,强度越来越强;特大雪灾年主要是由强降雪频次多、雪量大、强度强、持续时间长造成,而重雪灾年成因较复杂;太阳黑子活动低值年、斯堪的纳维亚正位相环流型及AO指数异常偏弱,阿勒泰地区易发雪灾。

Past research has shown it is difficult to objectively assess the snow disaster of the actual situation on the basis of nature factor purely as to determine the snow disaster severity. We used the maximum snow depth,precipitation month by month,the temperature every day from 7 meteorological stations in Altay from 1961 to 2012,and precipitation from April to September,accumulated temperature greater than zero,the actual data of snow disaster situation over the same period,sunspot and herbage data from 2007 to 2012,studied the index and the causes of snow disaster in this area. The result showed that the comprehensive index of snow disaster has high accuracy for evaluating the snow disaster and the snow disaster could be divided into 4 classes： The most snow disaster years,secondary heavy snow disaster years,moderate snow disaster years and light snow disaster years. The most snow disaster years and secondary heavy snow disaster years mainly occurred in the early twenty-first Century,and the strength was more and more strong; The cause of the most snow disaster is the high frequency of heavy snowfall,and the strength is more and more strong; that of the most snow disaster years were mainly caused by the much more heavy snowfall frequency,the large amount of snow,stronger strength,long duration,but the cause of secondary heavy snow disaster years was more complex; sunspot activated low value years,Scandinavia positive phase circulation pattern,and the AO index was very weak,secondary heavy snow disaster occurred easily in Altay.