近10年西藏高原雪线时空变化及其与气象因素关系分析

本文利用2000年3月-2011年2月西藏地区的MODIS雪盖产品数据、DEM数据以及地面气象观测数据，结合GIS空间分析方法，分析了西藏地区不同自然区划地带下雪线的时空变化特征及其与气象因素的关系。研究表明：西藏及各区域年平均雪线波动变化比较平稳，全区年平均雪线为4848.6m，呈微弱上升趋势，线性倾向率为6.54m/10a；各季节平均雪线中，秋季雪线的变化对年平均贡献最大，二者相关系数达0.796。冬季雪线呈下降趋势（相关系数为-0.625），其余三季则均表现为上升趋势，但均不显著；除东喜马拉雅南翼山地雪线逐月变化波动明显外（标准差为60.3m），其余均表现为平缓波动形势；西藏地区的雪线空间分布基本上表现为由东南向西北方向逐步升高的态势，其中东南部和西北部雪线分布密集且复杂。中部雪线则相对较稀疏，其高、低值区分别与山脉和河谷分布相对应；整体上，西藏雪线与气温正相关，与降水量负相关，但是各区域四季雪线与气温、降水量之间又存在差异。雪线是积雪各要素特征变化最为敏感的指示器，研究西藏高原雪线的时空分布特征及其与气象因素之间的关系，对了解西藏高原乃至整个青藏高原的气候变化具有重要的意义。

Analysis of Spatial and Temporal Variation of Snow Line and Its Relationships with Meteorological Factors in Tibet Plateau in Recent 10 Years

Using MODIS Snow Cover from March 2000 to February 2011, DEM and climate data of surface meteorological stations of Tibet Plateau, the spatial and temporal variations of snow line over the different natural divisions in Tibet Plateau and its relationships with meteorological factors were analyzed with the help of spatial and statistics analysis function of GIS. The results indicated that snow line over Tibet and all different natural divisions in recent 10 years showed a stable and small upward trend, but the trend was not significant, increasing rate reached 6.45m/10a; and regional annual average snow line was 4848.6m. Among the four seasons, autumn mean snow line contributed the most to the annual one - the correlation coefficient between them reached to 0.796. Snow line which was on the decline with the correlation coefficient for -0.625 in winter, was characterized by rising trend in the other three seasons, but all trends were not significant; The monthly changes of snow line of montane evergreen broad-leaved forest in south side of eastern Himalayas fluctuated obviously with standard deviation for 60.3m, the rest of natural divisions in Tibet Plateau were characterized by gentle fluctuation situation; The snow line of Tibet Plateau was under the distribution of escalating from the southeast to the northwest, while the distribution of snow line was dense and complicated in the southeast and northwest of Tibet, furthermore, high and low areas respectively corresponded to mountains and valleys; Overall, snow line was positively correlated with temperature while negative with precipitation in Tibet Plateau. However, there were differences in the relationships between snow line and climate factors (temperature and precipitation) over the different natural divisions in four seasons. Snow line, which is the most sensitive indicator to the variation features of snow elements,this study researchs the spatial and temporal variation of snow line and its relationships with meteorological factors in Tibet Plateau ,and the study has important to understand the climate change in Tibet even through The Tibetan plateau