联合Lutan-1和Sentinel-1A SAR偏移量追踪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。中国自主研发的陆地探测一号(Lutan-1,LT-1)卫星在冰川位移监测中的应用潜力尚缺乏系统评估。选取中国西藏自治区错朗玛冰川为实验对象,分别采用2022年哨兵1号A星(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解算冰川三维形变速率。研究结果表明,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,且LT-1在偏移量解算精度和空间分辨率方面均优于Sentinel-1A。实验结果显示,错朗玛冰川在2022年方位向和视线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2022-04—2022-09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。冰川顶部位移主要向东和北方向,呈现逐渐退缩趋势,冰川中部位移主要向西和北方向,冰川物质逐渐积累。冰川下部位移主要向东和北方向,呈现逐渐退缩的趋势。

     

    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 Experimental 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 a 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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