ICESat-2 ATL08地形和冠层高度产品精度评估

Accuracy Assessment of ICESat-2 ATL08 Terrain and Canopy Heights

ICESat-2 ATL08地形及冠层高度产品在大范围的森林资源调查研究中的性能还需进一步探究。为此,文章首先对35个生态网络观测站的ATL08地形及冠层高度产品进行整体的精度评估;其次,验证其在不同生物群落中的精度并对单站精度进行定量评价;最后,分析该产品在多种误差因素条件下的性能。结果表明:地形和冠层高度产品的整体RMSE分别为3.23 m和6.58 m;地形高度产品在低矮或稀疏的植被区精度较高,在高大或茂密的森林区精度较低,且其精度随坡度、植被覆盖度及冠层高度的增加而降低;冠层高度产品在温带阔叶林和混交林地区的%RMSE为34.78%,在沙漠和干旱灌木丛地区的%RMSE为127.47%。另外,相比地形高度产品,冠层高度产品受地物覆盖类型、冠层高度和植被覆盖度的影响更严重且影响机制较为复杂。

The performance of ATL08 terrain and canopy height products over a wide range requires further evaluation in the research on forest resources surveys.In this study,we validated the accuracy of ATL08 terrain and canopy height products from 35 national ecological observatory network sites.Secondly,we verified the accuracy of ATL08 terrain and canopy height products in different biomes and quantified the accuracy of ATL08 terrain and canopy height products at individual sites.Finally,the performance of ATL08 terrain and canopy height products was analyzed under conditions of multiple error factors(signal-to-noise ratio,slope,canopy height,land cover type,and leaf area index).Results show that the RMSE of overall terrain height and canopy height is 3.24 m and 6.58 m,respectively;terrain height product is better in low or sparse vegetation areas but worse in temperate broadleaf and mixed forests and temperate conifer forests;the RMSE value of terrain height increases as the slope,canopy cover,and canopy height increase;the %RMSE of canopy height is 34.78%in temperate broadleaf and mixed forests and it is %127.47% in deserts and xeric shrublands.The signal-to-noise ratio,land cover type,and canopy cover are more heavily and complicatedly impacted by canopy height than terrain height.