利用自动气象站数据和MODIS(MOD02)数据,对位于藏北高原多年冻土区的阿雅克气象站、卓乃湖气象站、唐古拉气象站和西大滩气象站四个观测站点的单点地表反照率的季节变化、日变化和站点所属区域(88°~95°E,32°~38°N)的区域地表反照率夏、冬季节的空间分布进行了分析研究,得出:2013年,四个研究站点地表反照率均是夏季最小,冬季最大,春季大于秋季,其他季节较夏季地表反照率峰值较多;当太阳高度角大于40°时各站点地表反照率日变化基本不变,地表冻融过程中地表反照率完全冻结阶段 > 日冻融循环阶段 > 完全融化阶段,且地表日冻融循环阶段地表反照率日变化的中间时刻有明显下降。研究区域夏、冬季地表反照率大部分在0.1~0.3范围内;冬季地表反照率大于0.3的区域明显多于夏季,夏季区域地表反照率自阿雅克到唐古拉呈带状递减。
Based on the data of four AWSs (automatic weather station) located in permafrost region of northern Tibetan Plateau including AYKMS, ZNHMS, TGLMS and XDTMS and MOD02 data of study area (88°-95° E, 32°-38° N) in 2013, the characteristics of diurnal variation and seasonal variation of surface albedo at these AWSs and spatial distribution of surface albedo of the study area in summer and winter are analyzed. It is found that the values decreased in the following order: winter, spring, autumn and summer. The number of the peaks of surface albedo in winter, spring and autumn was more than that in summer. When solar altitude angle was greater than 40, surface albedo basically remain unchanged. The values of surface albedo in ground freezing and thawing process ranked as frozen completely stage 〉 diurnal freeze-thaw cycle stage 〉 thawed completely stage, and during the diurnal freeze-thaw cycles, surface albedo decreased significantly in the middle period of every day. The values of surface albedo was majority between 0.1 to 0.3 in both summer and winter. In winter, the area where surface albedo was greater than 0.3 was significantly greater than that in summer. Surface albedo reduced from AYKMS to TGLMS in the study area in summer.