吉林省降雪初终日时空变化特征

利用吉林省1961-2015年逐日降水和天气现象资料,对降雪初、终日的时空变化特征进行了分析。结果表明:吉林省降雪平均日期始于10月22日,止于次年4月18日。降雪初、终日存在空间差异,东部山区开始早结束晚,西部平原开始晚结束早。降雪初、终日的空间第一模态为全省一致的偏早(晚)型,初日第二空间模态为南北反向型,终日第二向量场为东西反向型。初日集中在10、11月,以10月中旬出现概率最大,终日集中在3-5月,以4月中旬出现概率最大。初日存在8 a强显著周期,终日存在5 a强显著周期。降雪初、终日与大气环流有直接关系,初日推迟年西太平洋副高面积偏小、偏北,提前年副高面积偏大、偏南;终日推迟年副高面积偏小、偏南,提前年副高面积偏大、偏北。降雪初、终日还与地理环境有关,降雪初日随海拔的降低呈推迟趋势,终日则随着纬度升高和海拔降低呈提前趋势。

Spatiotemporal Change of the Beginning and Ending Dates of Snowfall in Jilin Province

The spatiotemporal changes of the beginning and ending dates of snowfall in Jilin Province were analyzed based on the data of daily precipitation and weather phenomena during the period of 1961-2015. The results showed that there were the spatial differences of the beginning and ending dates of the snowfall in Jilin Province,the beginning time of snowfall in the eastern mountainous area was early but the ending time was late,the ending time of snowfall in the western plain was early but the beginning time was late,the average snowfall dates began on October 22 and ended on April 18 next year. The first spatial pattern of beginning and the ending dates of snowfall was the early (late) pattern in the whole province. The second spatial pattern of beginning dates were the north-south reverse pattern,and the second spatial pattern of ending dates was the east-west reverse pattern. The beginning dates of snowfall occurred mainly in October and November,especially in mid-October,and the ending dates occurred mainly in April and May,especially in mid-April. There was a significant 8-year period of beginning dates of snowfall and a significant 5-year period of ending dates. There was a direct relationship between the beginning and ending dates of snowfall and the atmospheric circulation,the area of the West Pacific subtropical high was smaller and farther northward in the late years of the beginning dates but larger and farther southward in the early years. The area of the West Pacific subtropical high was smaller and farther southward in the late years of the ending dates of snowfall but larger and farther northward in the early years. The beginning and the ending dates of snowfall were also related to the geographical factors,they delayed with the decrease of altitude,while the ending dates became earlier with the increase of latitude and the decrease of altitude.