2000~2016年青藏高原地表反照率时空分布及动态变化

应用MODIS地表反照率产品MCD43C3，结合青藏高原自然带数据、积雪覆盖率和植被指数数据，采用一元线性回归方法分析了2000~2016年青藏高原地表反照率的分布及变化特征，结果表明:1）高原地表反照率空间分布差异大，整体上东南部低、西北部高，受地形和地表覆盖影响较大。2）高原地表反照率四季的空间分布变化明显，高海拔山脉和高寒灌丛草甸是高原地表反照率年内和年际变化的敏感地区。3）高原地表反照率年变化介于0.19~0.26，一定程度上表现为“双峰单谷”型，与地表覆盖类型的季节变化密切相关。4）高原地表反照率年际变化整体呈缓慢波动减小的趋势，平均变率约为－0.4×10-3 a-1，减小的区域约占高原总面积的66%，川西 —藏东针叶林带的西南部地区减小得最快，减小速率超过1.0×10-2 a-1。5）高原地表反照率减小与冰川消融和积雪减少密切相关，高原植被覆盖改善也是一个重要因素。

Spatial-Temporal Distribution and Variation of Land Surface Albedo over the Tibetan Plateau during 2000-2016

To accurately describe the spatial-temporal distribution and variation of land surface albedo over the Tibetan Plateau (TP), the spatial-temporal distribution and variation of land surface albedo over the TP from 2000 to 2016 are statistically analyzed in the present study based on MODIS (MODerate resolution Imaging Spectroradiometer) surface albedo data MCD43C3, natural geographic zones data of the TP, and data of snow cover fraction and vegetation index. The main results are as follows:1) There exists large spatial variation of land surface albedo, which is low over the southeastern plateau and high over the northwestern plateau due to influences of topography and surface cover. 2) The spatial distribution of land surface albedo changes obviously with season. High-elevation mountain ranges and alpine shrub meadows are sensitive areas for annual and interannual variations of land surface albedo over the TP. 3) Land surface albedo over the TP varies between 0.19-0.26 annually, and partly shows a double peak and single valley pattern, which is closely related to seasonal changes of land cover types. 4) In general, during the past 17 years, the interannual variation of land surface albedo indicates that the annually averaged albedo over the TP decreases gradually with an average rate of -0.4×10^-3 a^-1 that covers 66% of the entire plateau. Land surface albedo decreases most obviously with a rate of more than 1.0×10^-2 a^-1 in the southwestern of coniferous forest belt which is in western Sichuan and eastern TP. 5) Seasonal snow loss and glacier ablation are closely related to the decrease of land surface albedo over the TP, and the improvement of vegetation cover is also an important reason.