1961-2019年北疆冬季不同等级降雪变化特征

Variation Characteristics of Different Levels of Snowfall in Winter over Northern Xinjiang from 1961 to 2019

利用1961—2019年冬季北疆45个国家站逐日降水观测资料,采用统计分析方法,对不同等级降雪的气候变化特征进行了分析。结果表明:近59 a北疆降雪日数、降雪量、降雪强度分别以0.41 d/10 a、3.13 mm/10 a、0.15(mm·d^(-1))/10 a的速率增加,其中降雪量对全年降水量的贡献以1.3%/10 a的速率增长。降雪日数、降雪量主要表现为中雪和大雪的增加,降雪强度主要表现为暴雪强度的增加。小雪对降雪日数、降雪量的贡献呈减少趋势,其余等级为增加趋势,以中雪降雪日和大雪降雪量的贡献最为明显。北疆降雪日数仅在1月表现为减少趋势,主要是小雪日数显著减少;冬季各月降雪量均表现为增加趋势,主要是中雪和大雪降雪量显著增加。21世纪前10 a是降雪日数和降雪量最多的时期,20世纪60年代和21世纪10年代是降雪日数较少的时期。北疆降雪量在1985年发生突变,突变后年平均降雪量增加了12.4 mm。对比丰雪年和枯雪年,丰雪年降雪量偏多主要是小雪以上等级降雪日数的增多。

Based on the daily precipitation records of 45 national weather stations in northern Xinjiang from 1961 to 2019,the characteristics of different levels of snowfall were analyzed by using statistical analysis method.The results showed that the number of snowfall days,snowfall amount,snowfall intensity and contribution of snowfall to annual precipitation increased with the rate of 0.41 d/10 a,3.13 mm/10 a,0.15(mm·d^(-1))/10 a,and 1.3%/10 a in northern Xinjiang during 1961-2019,respectively.The number of snowfall days and the amount of snowfall were mainly increased by the moderate snow and heavy snow,and the snowfall intensity was mainly increased by blizzard intensity.The contribution of light snow to the number of snowfall days and the amount of snowfall showed a decreasing trend,the other levels showed an increasing trend,and the contribution of medium snow days and heavy snow amount were the most obvious.The number of snowfall days in January showed a decreasing trend in northern Xinjiang,which was mainly due to the significant decrease of light snowfall days.In winter,the number of snowfall days showed an increasing trend,which was mainly due to the significant increase of moderate and heavy snow.The highest number of snowfall days and snowfall was occurred in the 2000 s,and the fewer snowfall days was occurred in the 1960s and the 2010s.The snowfall in northern Xinjiang changed abruptly in 1985,and the annual average snowfall increased by 12.4 mm after the change.Compared with poor snow year and rich snow year,more snow in rich snow year was mainly due to the increase of the number of snowfall days above light snow level.