偏振激光雷达探测大气—水体光学参数廓线
Detecting atmospheric-water optical property profiles with a polarized lidar
- 2019年23卷第1期 页码:108-115
纸质出版日期: 2019-1 ,
录用日期: 2018-4-24
DOI: 10.11834/jrs.20197535
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纸质出版日期: 2019-1 ,
录用日期: 2018-4-24
扫 描 看 全 文
周雨迪, 刘东, 徐沛拓, 毛志华, 陈鹏, 刘志鹏, 刘群, 唐培钧, 张与鹏, 王雪霁, 任佳炜, 金时伟. 2019. 偏振激光雷达探测大气—水体光学参数廓线. 遥感学报, 23(1): 108–115
Zhou Y D, Liu D, Xu P T, Mao Z H, Chen P, Liu Z P, Liu Q, Tang P J, Zhang Y P, Wang X J, Ren J W and Jin S W. 2019. Detecting atmospheric-water optical property profiles with a polarized lidar. Journal of Remote Sensing, 23(1): 108–115
激光雷达在上层水体垂直廓线的遥感中展现出巨大优势。本文研制了一套高垂直分辨率的实时探测偏振激光雷达,提出了一种基于偏振激光雷达回波信号的反演算法,采用Fernald理论和多次散射原理反演非均匀大气—水体的衰减和退偏光学产品,以高效稳定地处理偏振激光雷达实验数据。展示了一个中国内陆水体激光雷达探测实例,观测到了两次气溶胶积聚现象和一次水体浑浊现象。对实验数据的分析表明,退偏比主要由前向多次散射和后向单次散射产生的退偏两部分组成。当多次散射强度较大时,退偏比的变化主要取决于多次前向散射退偏;反之,则主要依赖于单次后向散射退偏。
The ocean covers more than 71% of the Earth. Studies on vast oceans are of great significance for resource utilization and climate change. Several methods have been employed to detect the interior of the ocean. In-situ methods can accurately obtain marine information but their efficiency is limited. Ocean color remote sensing can collect global data. However
the limited information about the depth and dependence on natural light restrict its applications. Acoustics are widely used for seawater profiling
but they can only work under water due to the high loss in air–water interface. LiDAR is an effective method used to deal with seawater profiling with few limitations of platforms and natural light
in which its applicable coverage is from the water surface to the depth with several tens of meters. A polarized lidar with high vertical resolution (approximately 0.225 m in the water and 0.3 m in the atmosphere) and real-time detecting capability was developed to detect the profile information of atmospheric-water particulates. The laser was linearly-polarized to obtain the polarized information about the water column. Two refractive telescopes were used to collect the backscattering light from the water. Two polarizers were set in front of the telescopes
which only transmitted return signals that were co-polarized or cross-polarized with the laser. A retrieval algorithm based on polarized lidar returns was proposed to obtain atmospheric-water attenuation and depolarized optical products
such as
extinction coefficient (atmosphere)
diffuse attenuation coefficient (water)
depolarized ratio (atmosphere and water)
forward depolarized coefficient (water)
and backward depolarized ratio (water). An experimental sample from the inland water in Xiakou Reservoir
China during the night between April 6 and 7
2017 was presented to discuss the physical meanings and scientific values of the optical products. The retrieved optical products presented the variation of atmospheric aerosols and water turbidity during the night. For the clear atmosphere
the depolarized ratio was approximately 0.01 and the extinction coefficient was approximately 0.08 m
–1
. However
they became 0.06 and 0.02 m
–1
respectively
when the atmosphere was interrupted by several aerosols. For the water column
the diffuse attenuation coefficient varied from 0.6 m
–1
to 0.4 m
–1
depolarized ratio was from 0.6 to 0.4
and forward depolarized coefficient was from 0.06 m
–1
to 0.02 m
–1
when water turbidity became constantly clear after the rainfall. The analysis showed that depolarized ratio can be divided into depolarizations caused by forward multiple scattering and backward single scattering. Diffuse attenuation coefficient can be employed to describe the intensity of multiple scattering and is related to the depolarization caused by forward multiple scattering. Furthermore
depolarized ratio depends on the depolarization caused by forward multiple scattering when multiple scattering is strong. Otherwise
depolarized ratio depends on the depolarization caused by backscattering. A polarized lidar was developed to detect atmospheric-water particulate profile information. A retrieval algorithm based on polarized lidar returns was proposed to obtain atmospheric-water attenuation and depolarized optical products. An experimental sample from the inland water in Xiakou Reservoir
China was presented. High-range-resolution optical products were obtained
and the variations of aerosols and water were observed. The analysis presented that depolarized ratio can be divided into depolarizations caused by forward multiple scattering and backward single scattering. Furthermore
depolarized ratio depends on the depolarization caused by forward multiple scattering when multiple scattering is strong. Otherwise
depolarized ratio depends on the depolarization caused by backscattering.
光学遥感激光雷达漫射衰减系数偏振多次散射
optical remote sensinglidardiffuse attenuation coefficientpolarizationmultiple scattering
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