2000-2014年西藏雅鲁藏布江流域积雪时空变化分析及对气候的响应研究

利用2000-2014年MODIS逐日无云积雪产品对雅鲁藏布江流域积雪特征的空间分布及变化、积雪随高程变化的规律进行了分析，并采用被动微波数据SMMR （1979-1987年）和SSM/I （1988-2008年）以及中国地面降水和气温0.5°×0.5°日值格点数据集，研究了雅鲁藏布江流域关键积雪参数对气候要素的响应等。结果表明：流域下游积雪日较大且变化剧烈；流域整体上呈显著减少的趋势；积雪日随高程的上升而增加；流域内降水呈不显著的增加趋势，而气温呈显著的增加趋势，最高气温对积雪变化影响最大；气温对积雪终日的影响明显高于积雪初日；在积雪消融期降水的增多促进了积雪的消融。

Spatiotemporal variations of snow cover over Yarlung Zangbo River basin in Tibet from 2000 to 2014 and its response to key climate factors

The improved MODIS daily snow-cover dataset processed by cloud-removal algorithm was used to investigate the spatio-temporal snow-cover variations from 2000 to 2014 over the Yarlung Zangbo River basin. Then the key snow cover parameters, such as snow-cover days (SCD), start of snow-cover days (SCS), melt out of snow-cover days (SCM), as functions of elevation were analyzed to study the correlations between snow-cover and elevation. Long term snow-cover dataset derived from the passive microwave data of SMMR (1979-1987) and SSM/I (1988-2008), and the China daily precipitation/temperature analysis products derived from National Meteorological Information Center (NMIC) were used to analyze the responses of key snow-cover parameters to climatic factors. The results suggested that:except the broad-leaved forest regions in the eastern Himalayas, the value of SCD over the downstream of the Yarlung Zangbo River had been large and the inter-annual variations of SCD had been also severe; the area decreasing trend of SCD had predominated rather than increasing trend from 1979 to 2008 over the basin; SCD had positively correlated with altitude (R²=0.90, P<0.01); precipitation over the basin had not significantly increased, while temperature had significantly increased at a level of 0.001, and the maximum temperature had impacted mostly on the snow-cover variation; the influence of air temperature on SCM had been significantly higher than that on SCS; the increase of precipitation had promoted the ablation of snow in snow melting season.