Abstract NASA's Ice, Cloud and Land Elevation Satellite-2 (ICESat-2) launched in the fall of 2018 and is collecting vegetation canopy height and terrain measurements globally. In this paper we validate the terrain and canopy heights estimated from 11 months of ICESat-2 data using airborne lidar data collected in southern Finland. Overall, the terrain heights from the ATL08 data product agreed with the airborne lidar with vertical errors less than 75 cm (mean = −0.07 m; MAE = 0.53 m, RMSE = 0.73 m; n observations = 909,467). ATL08 terrain heights had positive bias (33 cm) when permanent snow cover was present compared to the airborne lidar. Canopy heights derived from ICESat-2 varied significantly by the beam selection (i.e. strong versus weak). Use of the weak beams increased the underestimation of canopy height by 1.06 m and increased RMSE% by 8.08%. The lowest canopy height errors were associated with strong beam/night/summer ATL08 acquisitions, which underestimated canopy height by 0.56 m (Bias% = 3.18; RMSE% of 13.75%), followed by strong beam/day/summer acquisitions (Bias% = 2.85%; RMSE% = 14.77%). For this study area with managed, coniferous-dominated boreal forests, we found that ATL08 canopy height errors were lowest for canopy cover ranging from 40 to 85% and within this range, we found that on average, ICESat-2 missed the top 11–13% of canopy heights. At low canopy cover (

中文翻译：

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验证 ICESat-2 地形和北方森林树冠高度

摘要 NASA 的冰、云和陆地高程卫星 2 (ICESat-2) 于 2018 年秋季发射，正在全球范围内收集植被冠层高度和地形测量值。在本文中，我们使用在芬兰南部收集的机载激光雷达数据验证了根据 11 个月的 ICESat-2 数据估计的地形和冠层高度。总体而言，ATL08 数据产品的地形高度与机载激光雷达一致，垂直误差小于 75 cm（平均值 = -0.07 m；MAE = 0.53 m，RMSE = 0.73 m；n 观测值 = 909,467）。与机载激光雷达相比，当存在永久积雪时，ATL08 地形高度具有正偏差（33 厘米）。来自 ICESat-2 的冠层高度因波束选择（即强与弱）而异。弱梁的使用使冠层高度的低估增加了 1。06 m，RMSE% 增加了 8.08%。最低的冠层高度误差与强光束/夜间/夏季 ATL08 采集相关，其将冠层高度低估了 0.56 m（偏差% = 3.18；RMSE% 为 13.75%），其次是强光束/日/夏季采集（偏差% = 2.85%；RMSE% = 14.77%）。对于这个有管理的、以针叶林为主的北方森林的研究区，我们发现 ATL08 冠层高度误差最低，冠层覆盖范围为 40% 到 85%，在此范围内，我们发现平均而言，ICESat-2 错过了前 11–冠层高度的 13%。在低篷盖 ( 对于这个有管理的、以针叶林为主的北方森林的研究区，我们发现 ATL08 冠层高度误差最低，冠层覆盖范围为 40% 到 85%，在此范围内，我们发现 ICESat-2 平均错过了前 11-冠层高度的 13%。在低篷盖 ( 对于这个有管理的、以针叶林为主的北方森林的研究区，我们发现 ATL08 冠层高度误差最低，冠层覆盖范围为 40% 到 85%，在此范围内，我们发现平均而言，ICESat-2 错过了前 11–冠层高度的 13%。在低顶篷 (