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ICESat-2/ATLAS数据地面高程及植被冠层高度反演精度验证

Accuracy Verification of Ground Elevation and Vegetation Canopy Height Inversion from ICESat-2/ATLAS Data

  • 摘要: 为验证新一代冰、云和陆地高程卫星ICESat-2/ATLAS陆地与植被高程产品(Land and Vegetation Height)ATL08数据地面高程和植被冠层高度的反演精度,以ICESat-2/ATLAS ATL08产品为研究对象,以黑龙江省帽儿山国家森林公园为研究区域,以高精度机载激光雷达数据及样地实测数据为参考,分析不同波束强度、时间、坡度及植被覆盖度下地面高程和植被冠层高度反演精度差异。研究表明,1)对地面高程来说,ATL08强波束的反演精度均方根误差(RMSE)为1.9 m,平均绝对误差(MAE)为1.1 m,弱波束的精度RMSE为4.1 m, MAE为2.0 m; 2)对植被冠层高度来说,以高精度机载激光雷达数据提取冠层高度为参考,强波束的反演精度RMSE为2.7 m, MAE为2.3 m,弱波束RMSE为5.4 m, MAE为3.7 m。以样地实测树高数据为参考,夜间所有波束精度RMSE为1.8 m, MAE为1.6 m; 3)随着坡度从0°增加到20°以上,地面高程反演精度的RMSE从2.3 m增大到7.7 m,植被冠高反演的RMSE从3.8 m增大到10.4 m; 4)中低植被覆盖度范围(0%~80%)内,ATL08产品能较好地测量出地面高程,RMSE均小于1 m。高植被覆盖度(80%~100%)区域反演精度RMSE为3.5 m。在中等植被覆盖范围(40%~80%)内,ATL08产品能较为准确地测量出植被冠层高度,RMSE为2.6 m。植被覆盖度过高(80%~100%)或者过低(0%~40%),其精度都会下降,RMSE为4.6 m和3.3 m。ATL08数据反演地面高程和植被冠层高度的精度强波束优于弱波束,夜晚波束优于白天波束,夜晚强波束精度最高。随着坡度的增加,不同波束的地面高程和植被冠高反演误差均逐渐增大,坡度越大误差越大。地面高程反演在中低植被覆盖度情况下较为准确,植被冠层高度反演精度在中等植被覆盖度情况下达到最高。

     

    Abstract: To verify the inversion accuracy of ground elevation and vegetation canopy height based on Land and Vegetation Height from ATL08 data of ICESat-2/ATLAS, a new generation of Ice, Cloud and Land Elevation satellite, in this study, the ICESat-2/ATLAS ATL08 product was taken as the research object, Maoer Mountain National Forest Park in Harbin City, Heilongjiang Province, China was taken as the research area, and high-precision airborne lidar data and sample data were taken as references to analyze the inversion accuracy differences of ground elevation and vegetation canopy height under different beam strength, time, slope and vegetation coverage. The results showed that:(1) for the ground elevation, the inversion accuracy RMSE and MAE of ATL08 strong beam were 1.9 m and 1.1 m, and the accuracy RMSE and MAE of weak beam were 4.1 m and 2.0 m.(2) For the vegetation canopy height, with the canopy height extracted from high-precision airborne Lidar data as a reference, the inversion accuracy of strong beam RMSE was 2.7 m, MAE was 2.3 m, weak beam RMSE was 5.4 m, MAE was 3.7 m. With the measured tree height data of the sample site as reference, the RMSE and MAE of all beams at night were 1.8 m and 1.6 m.(3) With the slope increasing from 0° to more than 20°, the RMSE of ground elevation increased from 2.3 m to 7.7 m, and the RMSE of vegetation canopy height inversion increased from 3.8 m to 10.4 m.(4) Within the range of medium and low vegetation coverage(0%-80%), ATL08 product can measure the ground elevation well, and the RMSE was all less than 1 m. The inversion accuracy RMSE for high vegetation coverage(80%-100%) area was 3.5 m. Within the range of medium vegetation coverage(40%-80%), ATL08 product can accurately measure the height of vegetation canopy with RMSE of 2.6 m. If the vegetation coverage was too high(80%-100%) or too low(0%-40%), its accuracy would decrease, with RMSE of 4.6 m and 3.3 m. ATL08 data inversion of ground elevation and vegetation canopy height showed that the accuracy of strong beam was better than weak beam, night beam was better than daytime beam, and the night strong beam accuracy was the highest. With the increase of slope, the inversion errors of ground elevation and vegetation canopy height of different beams gradually increased, and the error increased with the increase of slope. The inversion of ground elevation was more accurate in the case of medium and low vegetation coverage, and the inversion accuracy of vegetation canopy height reached the highest in the case of medium vegetation coverage.

     

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