近50 a西北干旱区冬季积雪日数变化特征

论文基于西北干旱区104个站点1961—2010年的日积雪深度、日平均气温、日降水量数据和NCEP/NCAR数据,利用K-means聚类分析、Mann-Kendall法等方法,对西北干旱区冬季积雪日数的时空变化特征及其变化原因进行分析。结果表明:1)冬季积雪日数大值主要集中在阿尔泰山和准噶尔盆地地区,西辽河流域、鄂尔多斯高原、天山、塔里木、阿拉善高原地区冬季积雪日数相对较少,内蒙古高原地区冬季积雪日数基本呈由高纬地区向低纬地区减少的趋势。2)近50 a,西北干旱区冬季积雪日数呈增加趋势,且各区域主要在1984年发生突变现象。内蒙古高原地区内站点冬季积雪日数变化较大,其他分区内站点的冬季积雪日数基本无变化。3)西北干旱区各分区周期变化主要集中在5、10、25 a左右,其中25 a的周期变化最为明显。4)冬季东亚大槽、南支槽的减弱与西风的增强使西北干旱区降水量增加是导致西北干旱区冬季积雪日数增加的主要原因。

Variation Characteristics of Snow Cover Days in Winter in Arid Region of Northwest China in Last 50 Years

In this paper, the daily datasets of snow depth, mean air temperature, and precipitation from 104 meteorological stations and NCEP/NCAR were used to study the snow cover days in winter in the arid region of Northwest China during 1961-2010. K-means clustering, Mann-Kendall test and other methods were used to calculate the temporal-spatial characteristics of the snow cover days and interpret the reason of the climate change. The results indicated that: 1) More snow cover days in winter mainly distributed in Junggar Basin and Altai Mountains (i.e. the region of III). The snow cover days in winter decreased gradually from high latitude to low latitude in the Inner Mongolia Plateau (i.e. the region of I). The snow cover days in winter were relatively few in the Xiliao River Basin, Ordos Plateau, Alxa Plateau, Tianshan Mountains and Tarim Basin (i.e. the region of II). 2) During the period 1961-2010, the snow cover days in winter presented an increased trend in the arid region of Northwest China, and the abrupt change was found in 1984. The big change of snow cover days in winter happened at some meteorological stations in the Inner Mongolia Plateau (i.e. the region of I), while snow cover days in winter had no obvious change at the stations in the Xiliao River Basin, Ordos Plateau, Alxa Plateau, Tianshan Mountains, Tarim Basin, Junggar Basin and Altai Mountains (i.e. the regions of II and III). 3) The variation of snow cover days in winter showed the periods of 5 years, 10 years, 25 years, approximately. The period of 25 years showed the most significance. 4) The increased precipitation in winter, caused by the weaken the East Asia major trough and Southern branch trough and the enhancement of the westerly wind, maybe the main factor of the increased trend of the snow cover days in winter in the arid region of Northwest China.