首页 >  2022, Vol. 26, Issue (1) : 138-147

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DOI:

10.11834/jrs.20221195

收稿日期:

2021-04-12

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高分七号卫星激光测高数据大型湖泊水位测量精度评估
李国元1,2,唐新明1,2
1.自然资源部国土卫星遥感应用中心, 北京 100048;2.江苏省地理信息资源开发与利用协同创新中心, 南京 210023
摘要:

卫星激光测高数据在湖泊水位测量方面具有重要的应用价值和独特优势,本文针对国产高分七号卫星上装备的线性体制全波形激光测高仪,开展在大型湖泊水位测量方面的应用探讨。介绍了高分七号卫星的基本参数,并与其他类卫星做了对比,分析了影响湖泊水位测量精度的卫星侧摆、大气散射、回波波形饱和等因素,研究了湖泊水面激光点的提取方法,结合ICESat、ICESat-2在青海湖和哈拉湖上的激光点开展了对比分析,并利用RTK-GPS测量方式对呼伦湖冰面激光点进行了实地精度验证。结果表明,高分七号卫星湖面激光点虽然稀疏,但内部一致性较好,其中青海湖面高分七号两波束激光高程标准偏差分别为0.056 m和0.080 m,与ICESat的0.079 m相当;相邻时间在哈拉湖同一湖面的高分七号两个波束与ICESat-2的高程均值相差分别为-5.2 cm和-8.0 cm;经实地测量评价两波束的湖面激光点绝对高程精度分别为:-0.030±0.109 m和-0.195±0.049 m。高分七号激光测高仪测量湖泊水位从精度上是可行的,但还存在激光重频率偏低、观测能力弱等问题。相关结论对于拓展高分七号卫星激光测高数据在大型湖泊水位测量的应用以及后续激光测高卫星的立项论证均具有参考价值。

Accuracy evaluation of large lake water level measurement based on GF-7 laser altimetry data
Abstract:

Lake level elevation and variation are important indicators for the global climate change, and satellite altimetry especially the laser altimetry data is a valuable data source. GF-7 laser altimeter as the first business application load with full-waveform can be used to measure the lake level, except for elevation control points. To evaluate the GF-7 satellite laser altimetry data on the lake, the basic parameters are introduced, and the relative and elevation accuracy of ICESat and ICESat-2 laser points located on large lakes is compared. The absolute elevation accuracy is analyzed by the field surveying result.A method to extract the GF-7 satellite laser altimetry points located on a large lake with high precision and reliability is presented, and the side-sway of the satellite, the atmospheric scatter, and echo waveform saturation that influence the elevation accuracy are discussed. The laser point with 1° side-angle can induce 0.106 m elevation error and the points on the lake less than 0.3° side-angle can be used to measure the lake level. The unique footprint image of GF-7 satellite is introduced to extract the laser points located on the lake. It can be used to judge the location of the laser point, whether it is in the lake or on the land and whether it is influenced by the cloud or dense fog and haze. Moreover, the saturation of echo waveform and the error elimination by median absolute deviation are introduced to ensure the reliability of the laser points.The absolute elevation accuracies of beam 1 and beam 2 are -0.030±0.109 m and -0.195±0.049 m, respectively, according to the field RTK-GPS surveying on the frozen Hulun Lake. The internal consistency of GF-7 laser points is better than that of ICESat laser points on Qinghai Lake, and beam 1 is slightly better than beam 2, with standard deviation of 0.056 and 0.080 m, respectively, which are equal to ICESat’s 0.079 m. Compared with ICESat-2, the lake surface points of GF-7 are sparser, but the accuracy is the same. The mean difference between the two beams of GF-7 and ICESat-2 in the same area of Hala Lake in adjacent time is -5.2 and -8.0 cm, respectively.The laser altimeter of GF-7 satellite can effectively obtain the water level of large lakes, and the relative and absolute elevation accuracy of GF-7 satellite laser altimetry points after extraction is equal to the ICESat and ICESat-2 laser points in the large lake. Under certain conditions, GF-7 laser altimeter can measure lake water level in terms of accuracy, but some problems, such as low repetition frequency of laser and weak observation ability, still exist. The conclusion can be viewed as reference for the next generation laser altimetry satellite, such as the land and sea laser satellite of China. Also, the combined of different satellite laser altimetry data on the lake maybe an effective way for the future application.

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