联合LuTan-1和Sentinel-1A应用SAR偏移量技术的错朗玛冰川位移监测

Joint Monitoring Glacier Displacement of the Cuolangma Glacier Based on LuTan-1 and Sentinel-1A Imageries with SAR Offset Tracking

  • 摘要: 全球气候变暖导致冰川积雪加速消融,造成一系列冰川泥石流、冰湖溃决等地质灾害。我国自主研发的LuTan-1(LT-1)卫星在冰川位移监测应用中的实际效果备受关注,且目前研究较少。本文选取我国西藏错朗玛冰川为实验对象,分别采用2022年Sentinel-1A影像和LT-1影像,对冰川位移进行了偏移量监测技术的对比研究,并利用Helmert方差分量估计方法联合两种影像数据解算冰川三维形变速率。研究表明,中值窗口偏移量解算方法和均值窗口偏移量解算方法均能提高偏移量解算的精度,同时表明了LT-1比Sentinel-1A具有更高的偏移量解算精度和结果空间分辨率。实验结果还显示,错朗玛冰川在2022年方位向和视线向(line of sight,LOS)向最大累积形变量分别为21.45 m和-7.61 m。联合解算的三维形变速率结果表明,冰川在2022年4月-9月期间,东西向、南北向和垂直向最大形变速率分别为-0.125 m/d、0.147 m/d和-0.134 m/d。该冰川顶部位移主要向东和北方向,表现出逐渐退缩趋势;冰川中部位移主要向西和北方向,冰川物质逐渐积累;而冰川下部位移主要向东和北方向,也呈现逐渐退缩的趋势。本研究为评估我国LT-1卫星性能及高海拔地区冰川位移监测提供了参考。

     

    Abstract: Objectives: Against the backdrop of global climate warming accelerating the melting of glaciers and snow, which in turn triggers geological disasters such as glacier debris flows and glacial lake outburst floods, monitoring glacier displacement using China's independently developed LuTan-1 (LT-1) satellite helps fill the gap in the currently limited research on this topic. Methods: We selected the Cuolangma Glacier in Tibet, China, as the experimental subject and conducted a comparative study of glacier displacement using offset tracking techniques with Sentinel-1A imagery and LT-1 imagery from 2022. Additionally, the Helmert variance component estimation method was applied to jointly process both datasets to calculate the glacier's three-dimensional deformation rate. Results: The results indicate that both the median window and mean window offset tracking methods improve the accuracy of offset calculations. It also shows that LT-1 provides higher offset calculation accuracy and spatial resolution compared to Sentinel-1A. Experimental results further reveal that the maximum cumulative displacements of the Cuolangma Glacier in 2022 along the azimuth and line-of-sight (LOS) directions were 21.45 m and -7.61 m, respectively. The jointly processed three-dimensional deformation rate results show that, from April to September 2022, the maximum deformation rates of the glacier in the east-west, north-south, and vertical directions were -0.125 m/d, 0.147 m/d, and -0.134 m/d, respectively. The displacement of the glacier's upper part primarily occurred towards the east and north, showing a gradual retreat trend; the displacement in the middle part primarily occurred towards the west and north, with glacier material gradually accumulating; and the displacement in the lower part primarily occurred towards the east and north, also showing a gradual retreat trend. Conclusions: The LT-1 satellite data from China, using offset tracking technology, can effectively monitor glacier movement and shows superior performance compared to Sentinel-1A. The joint processing method provides a valuable reference for three-dimensional glacier monitoring in the high-altitude regions of Tibet.

     

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