基于星载激光雷达光子分布特征的湖面近岸水体浊度反演

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Inversion of nearshore lake water turbidity based on photon distribution characteristics from spaceborne lidar

CHENHeng，HE Rong*，WU Xiaoling，ZHANG Shuaishuai，ZHU Chenchen （School of Surveying and Land Information Engineering ，Henan Polytechnic University ， Jiaozuo 454000，China） * Corresponding author， E -mail：hero@hpu.edu.cn

Abstract： To enable the retrieval of nearshore lake-water turbidity using spaceborne LiDAR data，this study processed ICESat-2 data to extract photon-distribution characteristics over lake surfaces.Leveraging the observed variation in photon-distribution patterns under diferent turbidity conditions，turbidity levels were inferrd accordingly. Lake Erie，one of the North American Great Lakes，was selected as the study area. An adaptive-parameter pruned quadtree algorithm was employed to denoise the ATLO3 photon data from ICESat-2，isolating valid water-surface photon returns. Key photon features-penetration depth，photon density，and atenuation rate-were extracted from the processed data and matched with in situ turbidity measurements. A turbidity-retrieval model was then developed using machine-learning regression algorithms.Experimental results demonstrate that the Random Forest algorithm yields the best performance， achieving a coefficient of determination （ ∇R2， ）of O.91，a meanabsolute error（MAE）of1.66NTU，and a root mean square error（RMSE）of 2.17NTU ，indicating high retrieval accuracy within the O-5O NTU turbidity range.To further assess the method’sapplicability under different turbidity conditions，the dataset is divided into low-to-moderate turbidity （ （0-30NTU ）andhigh turbidity >30NTU ）subsets. Results show that retrieval accuracy is slightly higher for the low-to-moderate turbidity group. This study provides a novel technical approach for remote sensing-based monitoring of lake water turbidity.

Key Words： ICESat-2；nearshore lake surface water； turbidity inversion； lidar; random forest

1引言

水体浊度是衡量水质状况的重要参数，直接反映水中悬浮颗粒物浓度，对水生态系统结构与功能有重要影响，因此对其进行精确监测具有重要科学意义[1-2]。（剩余15040字）