Inversion and Validation of Ocean Surface Bio-optical Parameters Using Multiplatform Ocean LiDAR
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摘要: 海洋上表层生物光学参数的垂直特征对评估海洋初级生产力和碳循环至关重要。虽然激光雷达技术能够有效探测这些参数,但受限于经验模型在不同区域的适应性差异,反演结果通常存在较大偏差。针对该问题,该研究基于2023—2024年中国南海海域多平台激光雷达联合观测数据,结合区域适应性生物光学模型,实现了该海域生物光学参数剖面的高精度反演。其中,叶绿素a浓度剖面反演结果与原位数据一致性较高,决定系数(R2)为0.84,平均均方根误差(RMSE)为0.14 μg·L–1。通过误差传递模型量化分析表明,不同波段的光学敏感性差异显著影响误差分布,蓝光波段有效探测深度为70 m,显著高于绿光波段的58 m。蓝光波段在次表层叶绿素最大值层(SCML)的自身反演偏差较绿光波段低0.18 μg·L–1,进而阐明了各波段光学特性与自身偏差的内在关联,为提升复杂水体生物光学参数剖面反演的可靠性和开展误差分析提供了有效方法。Abstract: The vertical characteristics of biological optical parameters in the upper ocean are essential for evaluating marine primary productivity and the carbon cycle. Although ocean lidar can effectively detect these parameters, the inversion results are usually highly biased due to the regional differences in the adaptability of empirical models. This study uses multiplatform lidar observations collected in the South China Sea (2023–2024), combined with a region-adaptive bio-optical model, to achieve high-precision profiling of bio-optical parameters in the region. The derived vertical profiles of chlorophyll-a concentration showed strong agreement with in-situ measurements, with a coefficient of determination (R2) of 0.84 and an average root mean square error of 0.14 μg·L–1. Further quantitative analysis using an error transfer model revealed that differences in band-specific optical sensitivity considerably affected error distribution. The effective detection depth in the blue band was 70 m, notably higher than the 58 m depth in the green band. In addition, at the subsurface chlorophyll maximum layer, the inversion bias in the blue band was 0.18 μg·L–1 lower than that in the green band, highlighting the intrinsic relationship between the optical characteristics of each wavelength and its associated bias. This result provides an effective method for improving the reliability of profile inversion of bio-optical parameters in complex waters and performing error analysis.
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Key words:
- Ocean LiDAR /
- Laser detection /
- Bio-optical parameters /
- Blue-green wave band /
- Error analysis
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图 8 典型站点的船载与机载海洋激光雷达反演的叶绿素a浓度剖面与原位RBR测量结果比较、标准差比较以及相应的信噪比剖面
Figure 8. Comparison of chlorophyll-a concentration profiles inverted by shipborne and airborne ocean LiDAR at typical sites with in-situ RBR measurement results, standard deviation comparison, and corresponding signal-to-noise ratio profiles
表 1 船载雷达系统参数表
Table 1. Parameter table of shipboard LiDAR system
分系统 参数 描述 发射
系统单脉冲能量 200 mJ @ 532 nm;
120 mJ @ 355 nm;400 mJ @ 1064 nm重复频率 20 Hz 脉宽 ≤ 5 ns 发散角 ≤ 0.5 mrad 光束直径 ≈ 6.5 mm 接收
系统望远镜直径 60 mm 视场 16~60 mrad 滤色片 1 nm @ 532 nm;
3 nm @ 355 nm, 405 nm;
10 nm @ 680 nm探测器 Photomultiplier tube 采集
系统AD分辨率 14 bits 采样频率 PC @ 1 GHz 表 2 机载雷达系统参数表
Table 2. Parameter table of airborne LiDAR system
分系统 参数 描述 发射
系统单脉冲能量 2 mJ @ 486.1 nm;
5 mJ @ 532.2 nm重复频率 100 Hz 脉宽 2.5 ns @ 486.1 nm;
6 ns @ 532.2 nm发散角 5 mrad 接收
系统望远镜直径 200 mm 视场 28 mrad 接收光学带宽 0.44 nm @ 486.1 nm;
0.60 nm @ 532.2 nm探测器 Photomultiplier tube 采集系统 采样频率 1 ns 表 3 辅助参数说明
Table 3. Auxiliary parameter description
数据来源 参数 说明 RBR水质监测仪
(RBR XR-420, RBR, Canada)Chla 叶绿素a浓度剖面 Global Ocean Biogeochemistry
Analysis and ForecastChla 叶绿素a浓度 元素分析仪(UNICUBE, Elementar,
germany)POC 颗粒有机碳浓度 -
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