Shen Xue, Liu Zhipeng, Zhou Yudi, Liu Qun, Xu Peituo, Mao Zhihua, Liu Chong, Tang Longhua, Ying Na, Hu Miao, Liu Dong
Appl Opt. 2020 Apr 1;59(10):C21-C30. doi: 10.1364/AO.382201.
Seawater properties can be retrieved from oceanic lidar returns. However, the actual returns include the ideal returns convolved by the instrument response, which inevitably introduces retrieval error. In this paper, instrument response effects on the retrieval of oceanic lidar are analyzed from different aspects. The results demonstrate that the retrieval of the lidar attenuation coefficient near the water surface is affected by the instrument response in homogeneous water. Considering the ratio of the signal distortion region (relative error of attenuation >10) to the maximum detection depth (three dynamic ranges) is less than 20%, the pulse width of the instrument response should be less than 10. In addition, an average relative error of 55% will be introduced to the retrieval of phytoplankton layer thickness in the stratified water, which can be reduced to 6% after correcting for the influence of the instrument response. However, a relative error greater than 20% still exists when the instrument response length is two times larger than the layer thickness. These conclusions provide guidelines to a future design of oceanic lidar.
海水特性可从海洋激光雷达回波中获取。然而，实际回波包含由仪器响应卷积后的理想回波，这不可避免地会引入反演误差。本文从不同方面分析了仪器响应对海洋激光雷达反演的影响。结果表明，在均匀水体中，水面附近激光雷达衰减系数的反演受仪器响应影响。考虑到信号失真区域（衰减相对误差>10）与最大探测深度（三个动态范围）的比值小于20%，仪器响应的脉冲宽度应小于10。此外，分层水体中浮游植物层厚度反演会引入55%的平均相对误差，在校正仪器响应影响后可降至6%。然而，当仪器响应长度比层厚度大两倍时，仍存在大于20%的相对误差。这些结论为未来海洋激光雷达的设计提供了指导。
