新疆地区雪深和雪压的分布及其55年的变化特征分析

Distributions of snow depth and snow pressure in Xinjiang and their variation characteristics in 55 years

本文主要使用新疆地区109个气象站观测资料,对新疆地区雪深和雪压的分布和变化特征以及相关气象因子进行了系统分析,结果表明:新疆地区的积雪多年平均表现为北部多于南部,其中雪深和雪压最大值出现在新疆北部,数值分别为10 cm和10 g/cm^2.新疆积雪的季节特征较为明显,其中2月份积雪最大,雪深和雪压分别为9.2 cm和5.4 g/cm^2.冬季雪深和雪压最大值出现在新疆北部,到了春季有较大幅度的下降.新疆积雪的55年来的年际变化主要经历了较大幅度下降,而后呈波动式缓慢上升的过程,其中20世纪60年代是积雪最小的时期,呈波动式缓慢上升的趋势在冬季更为明显.较大幅度下降主要发生在50年代末到60年代初之间,其中年平均雪深和雪压的下降分别为2.53 cm和2.34 g/cm^2,冬季相应分别为4.41 cm和3.6 g/cm^2.对气象影响因子的地理分布特征分析表明,降水量表现为从西北向东部逐渐减小的特征,且和积雪成正的空间相关关系,其中冬季的相关系数最高,分别为0.82(雪深)和0.56(雪压).地面气温的分布特征为南高北低型,而且和积雪成负的空间相关关系,55年平均的相关系数最高,分别为-0.47(雪深)和-0.35(雪压).55年平均日照时数分布特征为西低东高型,东部最高能达到9.4hour/day.气象影响因子的年际变化趋势表明,降水量和年平均地面气温均有明显的上升趋势,其中年平均降水的增长率达到了1.36 mm·(10a)^(-1) ,年平均日照时数在60年代以后表现为明显下降的趋势.时间相关系数分析表明,雪深和雪压与降水量成正相关关系,与地面气温和日照时数成负相关关系,其中与降水量的相关系数最高,分别为0.401(雪深)和0.493(雪压),均通过了99%的信度检验.

A data set recorded at 109 stations of the Xinjiang Uygur Autonomous Region is used to analyze the spatial distributions and temporal changes of snow depth, snow pressure and climate variables （precipitation, temperatureand sunshine duration） for 55 years. The results show that： the average snow depth and snow pressure in northern Xinjiang are more than that in the south, and the maximum snow depth and snow pressure in the north are respectively 10 cm and 10 g/cm^2. The seasonal change of snow in Xinjiang was obvious, and the largest variation occurred in February, when snow depth and snow pressure were 9.2 cm and 5.4 g/cm^2. The maximum snow depth and snow pressure in winter appeared in northern Xinjiang, and it presented a large decline trend in spring. The interannual changes of snow in Xinjiang showed mainly rapid decrease trend since the 1950 s, and then rose slowly. The minimum snow occurred in the 1960 s, and the increasing trend in winter was more obvious than other seasons. The large decrease mainly occurred in the period of the late 1950 s to early 1960 s, in which the annual average decline in snow depth and snow pressure was 2.53 cm and 2.34 g/cm^2 , and 4.41 cm and 3.6 g/cm^2 in winter. The analysis of impact factors shows that the geographical distribution of precipitation gradually decreased from the northwest to the east in Xinjiang and it has positive spatial correlations with snow. The highest correlation coefficients were 0.82 （snow depth） and 0.56 （snow pressure） in winter. The surface air temperature was higher in the south in contrast with that in north of Xinjiang, with negative spatial correlation with snow, and the largest correlation coefficients were -0.47 （snow depth） and -0.35 （snow pressure） for annual average. The annual average sunshine duration was higher in the east than that in the west, and the maximum can reach 9.4hour/day in the east. The interannual trend of these impact factors shows that precipitation and surface air temperature had the increasing trend, in which the increasing rate of annual average precipitation reached 1.36 mm · （10a）^-1. The annum average sunshine duration shows a marked downward trend after the 1960 s. The temporal correlation coefficients show that snow depth and snow pressures had positive correlation with precipitation, and were negatively correlated with temperature and sunshine duration. The highest correlation with precipitation was 0. 401 （snow depth） and 0. 493 （snow pressure）, passing the 99% confidence level.