Study on the spatial and temporal variations of the surface albedo on Muz Taw Glacier,Sawir Mountains北大核心CSCD

冰川反照率时空变化特征研究对于评估冰川能量物质平衡及认识冰川消融过程至关重要。本文基于高空间分辨率的Landsat OLI影像和高时间分辨率的MOD10A1产品,并结合冰面反照率实测数据,开展了2011—2021年北疆萨吾尔山木斯岛冰川表面反照率的时空变化特征及其对冰川物质平衡影响的研究。结果表明:Landsat反演反照率和MOD10A1反照率与同期内冰面实测反照率的相关性分别为0.95和0.62,均显示木斯岛冰川表面反照率存在显著的时空变化特征;在空间尺度上,冰面反照率沿主流线整体随海拔升高呈增加趋势。但由于局部地形差异,反照率在海拔3 600 m以下区域随海拔升高出现下降趋势;在同一海拔处,反照率沿冰川两侧边缘向中部递增。2011—2021年,冰川年均反照率微弱增加,消融期内(5—8月)平均反照率与全年平均反照率的变化速率分别为0.0024 a-1和0.0017 a-1;逐月反照率具有显著的季节变化特征,6—8月冰面反照率较低(0.330),12月—次年2月冰面反照率较高(0.586);消融期内冰川消融区反照率下降幅度大于积累区。研究进一步表明,夏季(6—8月)平均反照率与冰川物质平衡存在显著的正相关(R=0.84,P<0.01),气温、固态降水、云量、太阳入射角、吸光性杂质等是影响冰川反照率变化的重要因素。该研究将对冰川消融过程和机理、能量物质平衡模拟等工作提供重要的基础支撑。

Study on the spatial and temporal variations of the surface albedo on Muz Taw Glacier， Sawir Mountains

Glacier surface albedo impacts the energy budget on the glacier surface， the variability of which strongly affects glacier melting and mass balance. Therefore， it is crucial to investigate the spatial and temporal variations of glacier surface albedo. Taking this into account， the spatial and temporal variations of albedo and the relationship between glacier surface albedo and mass balance were investigated using Landsat images， MODIS daily albedo products and the in situ measured albedo from Automated Weather Station installed on Muz Taw Glacier， Sawir Mountains during 2011 to 2021. The results indicated that the surface albedo derived from Landsat and MOD10A1 were consistent with the measured albedo for the same period with the coefficient of determination reaching to 0.95 （P<0.05） and 0.62 （P<0.01）， respectively. The significant spatial and temporal characteristics of albedo on Muz Taw Glacier were existed. On the spatial scale， the surface albedo increased with the altitude rising along the glacier central flowline. However， the albedo decreased with the altitude rising at an altitude of more than 3 600 m a.s.l. due to the topographic differences. At the same altitude， the albedo gradually increased from the glacier boundary to the middle part. During 2011 to 2021， the average surface albedo increased at the lower rate of 0.0024 a^-1 in the ablation period from May to August， and the annual average increase rate was 0.0017 a^-1 in the same period. The monthly average albedo changed obviously in the different seasons. It was lower from June to August with an average value of 0.330 and higher from December to February in the next year with an average value of 0.586. The albedo in the ablation zone decreased faster than that in the accumulation zone during the ablation period. The study further confirmed that there was a significant positive correlation between the average surface albedo in summer from June to August and the annual glacier mass balance with the coefficient of determination reaching to 0.84 （P<0.01）. Air temperature， solid precipitation， cloud amount， solar incident angle and light absorbing impurities were important factors affecting the albedo variation. This study will provide basic support for studying glacier ablation process and mechanism glacier energy and mass balance simulation， etc.