天山1号冰川厚度和冰下地形探测与冰储量分析

通过对天山乌鲁木齐河源 1号冰川的雷达回波探测 ,清晰地揭示出冰川底部冰 /岩界面的位置及其起伏变化特征 ,显示出雷达波对山地冰川良好的穿透能力和对冰下地形的高分辨能力 ,冰川雷达测厚的误差小于 1 .2 %。研究结果显示 ,1号冰川东支冰川平均厚度为 5 8.77m ,西支冰川平均厚度为 44.84m ,冰体厚度最大值发育于冰川中部趋于主流线位置。冰川冰储量计算表明 ,东支冰储量为 0 .0 5 1 868km3,西支冰储量为 0 .0 2 0 2 1 0km3。表面和底部地形有明显差异 ,主要因冰川动力过程对基岩强烈的地貌作用所致 ,意味着冰床的起伏地形对冰川浅层冰体的运动过程影响不显著。

GPS-derived horizontal ice flow velocities along the traverse route from Zhongshan Station to Dome-A, East Antarctica

We describe a radio echo sounding (RES) survey for the determination of ice thickness, subglacial topography and ice volume of Glacier No.1, in Tien Shan, China, using ground penetrating radar (GPR). Radar data were collected with 100 MHz antenna that were spaced at 4 m with a step size of 8 m. As our study shows, the GPR radar survey method works well on alpine glaciers in low latitude, high altitude China. Very clear bedrock echoes were observed in radar images. The images produced from GPR clearly show the continuity of bedrock echoes. The undulation of the bedrock surface, indicates that GPR radar survey provides for fundamental data on glacier thickness, subice topography and ice volumes, which can contribute new knowledge and better understanding of glacier dynamics, glacier fluctuation and climate change, glacial erosion processes as well as providing estimates of glacier water reserves. Radar results show that the maximum ice thickness of Glacier No.1 is 133m, the average thickness of east branch is 58.77m and that of west branch is 44.84m. And ice thickness along east branch main ice flow line of Glacier No.1 averages at 85.3m and ice thickness along west branch main ice flow line of Glacier No.1 averages at 66.5m. Based on the map of ice thickness, we know the thickest part of the glacier lies near the main flow line in the central area of the glacier. Ice volume calculations based on radar data provide support to the studies of glacier fluctuations and estimation of the glacial water reserves. For Glacier No.1, in Tien Shan, the ice volume of east branch is 51.87×10 6m 3, which of west branch 20.21×10 6m 3. Subglacial topography features revealed by glacier radar images show that bedrock is more undulating than the glacier surface topography, indicating that the amplitude of the bedrock undulation decreases with increasing distance above the bedrock. The surface relief does not vary with the of the bedrock on Glacier No.1. The morphologies of glacier valley cross sections differ greatly in different parts of the glacier, which helps us to understand the impacts of glacier valley cross sections on glacier motion.