陆地生态系统碳监测卫星（Terrestrial Ecosystem Carbon Inventory Satellite，TECIS）是我国首颗以激光雷达为主载荷，以高精度监测陆地生态系统碳储量、森林资源和森林生产力为主任务的遥感卫星，可服务国家“双碳”战略、全国重要生态系统保护和修复重大工程监测评价等工作。本文详细评估了陆地生态系统碳监测卫星激光测高全波形数据不同RH（Relative Height）指标表征森林冠层高度的能力，对比了固定增益和可变增益全波形森林冠层探测能力的差异，分析了坡度对冠层高度反演的影响。选取加拿大魁北克试验区的六轨数据进行试验分析，结果表明以RH0为冠层高度起算基准时，将明显高估冠层高度，提高计算背景噪声阈值的背景噪声标准差倍数有利于提高冠层高度精度，但效果有限，而以RH5为冠层高度起算基准将大大提升冠层高度精度，更大的RH起算基准如RH10以上则会低估冠层高度。陆地生态系统碳监测卫星固定增益全波形数据，以RH5为冠层高度起算基准，6倍背景噪声标准差计算背景噪声阈值，剔除少量异常激光点后，森林冠层不同百分比的高度反演精度的RMSE在3.58 m~4.23 m之间，ME小于1.0 m，MAE介于2.52 m~3.21 m之间。可变增益与固定增益全波形数据反演冠层高度的精度相当，但计算背景噪声阈值的背景噪声标准差倍数比固定增益更小。以RH5为冠层高度起算基准显著优于波形分解的最后波峰位置，并且受地形坡度的影响更小。可变增益和固定增益的配置有利于提高数据有效率。相关结论将有利于支撑陆地生态系统碳监测卫星激光测高数据在森林冠层高度反演中的应用。

The Terrestrial Ecosystem Carbon Inventory Satellite (TECIS) is China"s first remote sensing satellite with space-borne LiDAR as the main payload, which aim at quantitatively monitoring of terrestrial ecosystem carbon storage, forest resources and forest productivity, and serving the goals of "carbon peaking and carbon neutrality" and the monitoring and evaluation of major projects for the protection and restoration of important ecosystems in China. In this paper, the ability of different relative height (RH) metrics to characterize the forest canopy height was evaluated in detail for the full waveform data of the multi-beam LiDAR onboard the Terrestrial Ecosystem Carbon Inventory Satellite. Canopy heights were calculated using RH0, RH5, RH10, RH15, RH20 and last peak locaton as the benchmark. Different percent canopy height determined by RH100, RH95, RH90, RH85 and RH80 were obtained and compared to canopy height model(CHM) generated by airborne LiDAR data to explore the correlation between RH percent canopy height and CMH. The ability in canopy height detection between fixed-gain and variable-gain full-waveform was compared. Moreover, the influence of slope on canopy height extraction was analyzed. Six tracks of multi-beam LiDAR L2B data products from the Terrestrial Ecosystem Carbon Inventory Satellite passing the test area of temperate coniferous-broadleaved mixed forest in Quebec, Canada, were selected for analysis. The results show that the canopy height is overestimated significantly when RH0 is used as the benchmark of canopy height calculation, and the accuracy of canopy height is improved by increasing the background noise threshold with reference to the noise standard deviation, but the effect is limited. As for the fixed-gain waveforms, using RH5 as the benchmark, and identifying the threshold of background noise by 6 times the standard deviation of background noise, the accuracy of different percentage of forest canopy heights achieves RMSEs of between 3.58 m~4.23 m, MEs of less than 1.0 m and MAEs of between 2.52 m~3.21 m, respectively. The accuracy of retrieval canopy heights using variable-gain and fixed-gain full waveform data is comparable, but the times of background noise standard deviation for calculating background noise threshold is smaller than that of fixed gain. Start from RH5 and using proper background noise threshold, the canopy heights retrieved by RH100, RH98, RH95, RH90 and RH85 from both variable-gain and fixed-gain full waveform data were close to the 100% , 95% , 90% , 85% and 80% canopy height from CHM products within the footprint range, respectively. Moreover, using RH5 as the benchmark of canopy height is significantly better than the last peak position derived from waveform decomposition, and is less affected by terrain slope. The configuration of variable and fixed gains is beneficial for enhancing data effectiveness in forest areas. The conclusions will be helpful for the application of the laser altimetry data of Terrestrial Ecosystem Carbon Inventory Satellite in forest canopy height retrieval.