近10年黑河流域上游积雪时空分布特征及变化趋势

Spatio-Temporal Distribution Characteristics of Snow Cover in the Upper Reaches of Heihe River Basin over the Past 10 Years and the Variation Trend

基于黑河流域上游1960年-2011年降水、气温数据及2000年-2011年MODIS(Moderate-resolution Imaging Spectroradiometer)积雪产品,采用Mann-Kendall非参数检验和累积距平曲线,研究了降水、气温序列的变化趋势和突变点,分析了黑河流域上游积雪面积的年内分布过程和年际变化趋势,探讨了近10a来降水、气温变化对积雪覆盖面积的影响。结果表明:①黑河流域上游年平均气温呈显著的上升趋势,年降水量也呈微弱增加趋势;②黑河流域上游积雪面积年内分布呈双峰型,峰值分别出现在秋季和春季,夏季积雪面积最小;③2000年-2011年积雪面积呈微弱上升趋势,但各季变化不同。春、秋季积雪面积呈上升趋势,夏季为减少趋势,冬季没有明显的变化;④积雪频率有3个高值区,分布在黑河流域上游西岔札马什克水文站周围及以上区域。积雪频率与流域内高程存在显著的相关性;⑤各个季节积雪面积与气温呈负相关的关系;除秋季外,与降水呈正相关的关系。也即较大的降水在较低的气温条件下,有利于积雪的增加,温度的升高则使积雪面积减少。

Based on precipitation and temperature data of the upper reaches of Heihe River Basin from 1960-2011 and MODIS （Moderate-resolution Imaging Spectroradiometer） snow product data MOD 10A2 from 2000-2011, this paper has investigated the trends and mutation points of annual and seasonal precipitation and temperature in the upstream of Heihe River Basin during the past 50 years with the non-parametric Mann-Kendall test and accumulated difference curve. In addition, the intra-annual distribution and interannual variation trends of snow cover area have been analyzed and the impacts of precipitation and climate variation on snow cover over the past 10 years have been discussed. The results show that： 1） The average annual temperature in the upstream of Heihe River Basin shows an obviously increasing trend, and the annual precipitation shows an insignificantly increasing trend; 2） The annual distribution of snow cover over the upper reaches of Heihe River Basin presents a style of double peak, and the two periods with higher snow coverage are autumn and spring respectively. The snow cover area is the maximum in October and May, while reaching the minimum in July; 3） The snow cover area shows an insignificantly increasing tendency from 2000-2011, but the changing trends are different over different seasons. The snow cover area shows an increasing tendency in spring and autumn, a decreasing tendency in summer and no significant changing trend in winter; 4） There are three areas with high snow cover frequency, which are located near the Zhamashike hydrological station, the west branch of upper reaches of Heihe River and the upper area. The snow cover frequency has a significant correlation with DEM in the watershed, and the correlation coefficient reaches 0.748; 5） Snow cover has a significantly negative correlation with temperature in all seasons, and has a positive correlation with precipitation except in autumn. That is to say, more precipitation with lower temperature is favorable to the accumulation of snow, while the increase of temperature would reduce the snow cover area.