Laser sensing of a subsurface oceanic layer II Polarization characteristics of signals

Experiments on laser sensing of water under conditions simulating the operation of a laser radar mounted onboard an airplane have been carried out. Values of water extinction index reconstructed from lidar signals are presented, and their dependence on the lidar field-of-view angle is established. These data are compared with the results of calculations by the Monte Carlo method. The experimental and calculated data are described by analytical expressions that differ only by proportionality coefficients. Simultaneously with the lidar, the extinction index was measured with a reference submersible transmissometer. A regression dependence between the lidar-derived extinction factors ε biased due to multiple scattering from their true values and the reference values of ε measured with the transmissometer is obtained.

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“…Qualitatively, this experimental behavior coincided with the theoretical behavior of δ(z) reported in [6].…”

supporting

confidence: 87%

“…The qualitative functional dependence of the bias on the parameters of the lidar-sea system was simulated by the Monte Carlo method and measured experimentally in situations imitating airborne sensing. The algorithm of mathematical modeling of laser hydrooptical sensing and its accuracy were considered in detail in [6].…”

mentioning

confidence: 99%

Hydrooptical laser sensing under controllable conditions

et al. 2005

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“…For polarized light, β depends on the plane of polarization relative to ϕ. 33,34 In principle, the calculation continues until the photon passes through the plane of the receiver, where it is weighted by a factor expð− P a i l i Þ, where a i is the absorption coefficient along the i'th path segment (of length l i ). In practice, it is generally necessary to enhance the occurrence of low-probability backscattering events and compensate for this with an additional weighting factor.…”

Section: Basic Characteristicsmentioning

confidence: 99%

Review of profiling oceanographic lidar

Churnside

2013

Opt. Eng

144

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This paper provides a review of the development of profiling oceanographic lidars. These can provide quantitative profiles of the optical properties of the water column to depths of 20 to 30 m in productive coastal waters and to depths of 100 m for a blue lidar in the open ocean. The properties that can be measured include beam attenuation, diffuse attenuation, absorption, volume scattering at the scattering angle of 180 deg, and total backscattering. Lidar can be used to infer the relative vertical distributions of fish, plankton, bubbles, and other scattering particles. Using scattering as a tracer, lidar can provide information on the dynamics of the upper ocean, including mixed-layer depth, internal waves, and turbulence. Information in the polarization of the lidar return has been critical to the success of many of these investigations. Future progress in the field is likely through a better understanding of the variability of the lidar ratio and the application of high-spectral-resolution lidar to the ocean. Somewhat farther into the future, capabilities are likely to include lidar profiling of temperature in the ocean and an oceanographic lidar in space.

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“…Lidar systems have been proposed as an effective tool for oceanic research as demonstrated by a variety of measurements in the upper ocean, including profiling schools of fish [ Churnside et al ., ], bathymetry [ Guenther et al ., ], and ocean surface roughness and subsurface measurements [ Bufton et al ., ; Hu et al ., ; Krekov et al ., ]. Internal waves have also been detected through the phytoplankton signatures they induce [ Churnside et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Ocean subsurface studies with the CALIPSO spaceborne lidar

Trepte

et al. 2014

JGR Oceans

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The primary objective of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission is to study the climate impact of clouds and aerosols in the atmosphere. However, recent studies have demonstrated that CALIPSO also collects information about the ocean subsurface. The objective of this study is to estimate the ocean subsurface backscatter from CALIPSO lidar measurements. The effects of the lidar receiver's transient response on the attenuated backscatter were first removed in order to obtain the correct attenuated backscatter profile. The empirical relationship between sea surface lidar backscatter and wind speed was used to estimate the theoretical ocean surface backscatter. Then the twoway atmospheric transmittance was estimated as the ratio between the corrected ocean surface backscatter and the theoretical one. The ocean subsurface backscatter was finally derived from the subsurface attenuated backscatter divided by the two-way atmospheric transmittance. Significant relationships between integrated subsurface backscatter and chlorophyll-a concentration and between integrated subsurface backscatter and particulate organic carbon were found, which indicate a potential use of CALIPSO lidar to estimate global chlorophyll-a and particulate organic carbon concentrations.

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Laser sensing of a subsurface oceanic layer II Polarization characteristics of signals

Cited by 20 publications

References 2 publications

Hydrooptical laser sensing under controllable conditions

Hydrooptical laser sensing under controllable conditions

Review of profiling oceanographic lidar

Ocean subsurface studies with the CALIPSO spaceborne lidar

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