A Method for Correcting Water Diffuse Attenuation Coefficient Based on the Water Surface Lens Effect of High-Spectral Resolution LiDAR

Abstract

This invention discloses a method for correcting the water diffuse attenuation coefficient based on the water surface lensing effect of hyperspectral resolution lidar. It constructs a water surface lensing effect model to characterize the focusing phenomenon of pulse energy, uses ECKV wave spectrum to simulate the dynamic water surface, and tracks the laser pulse penetrating the water body based on the law of light refraction. The degree of pulse energy focusing is statistically analyzed using a two-dimensional histogram. Based on the unique molecular and particle separation characteristics of hyperspectral resolution lidar, the method corrects the overestimated water diffuse attenuation coefficient in shallow water areas due to the water surface lensing effect. This invention provides a new solution for correcting the water diffuse attenuation coefficient in shallow sea areas, contributing to improved water quality monitoring accuracy in shallow water regions.

Description

Technical Field

[0001] This invention belongs to the field of laser remote sensing technology, specifically relating to a method for correcting the water diffuse attenuation coefficient based on the water surface lensing effect of high spectral resolution lidar. Background Technology

[0002] Water quality monitoring plays an irreplaceable role as a crucial technical means for marine environmental health assessment, pollution risk early warning, and ecosystem sustainability maintenance. Among these, the diffuse attenuation coefficient, a key optical parameter characterizing water turbidity, not only objectively reflects the inherent optical properties of seawater but also provides crucial quantitative evidence for analyzing the material and energy cycle processes of marine ecosystems. With the iterative upgrades of water color remote sensing sensor technology and the improvement of the marine three-dimensional observation system, passive optical satellite systems have provided high spatiotemporal resolution water color element products and long-term time-series observation data support for global ocean monitoring. However, limited by sun-synchronous orbit design and daytime observation modes, traditional passive radiometric measurement techniques have significant coverage blind spots in polar seas and struggle to overcome the constraints of diurnal rhythms on continuous observation.

[0003] Active lidar technology, with its all-weather observation advantage, effectively compensates for the inherent defects of passive remote sensing systems. In particular, hyperspectral resolution lidar technology overcomes the "underdetermined equation" problem encountered by traditional elastic lidar in retrieving water parameters by separating Mie scattering (particle scattering) and Rayleigh scattering (molecular scattering) signals in the echo signal. However, the pulse energy focusing phenomenon caused by the water surface lensing effect leads to an overestimation of the water diffuse attenuation coefficient in shallow water areas. Therefore, designing a reasonable hyperspectral resolution lidar water diffuse attenuation coefficient correction method is crucial and has significant theoretical and practical value for improving the marine three-dimensional observation technology system. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a method for correcting the water diffuse attenuation coefficient based on the water surface lensing effect of hyperspectral resolution lidar. By utilizing the water surface lensing effect generated by hyperspectral resolution lidar, the method can accurately correct the water diffuse attenuation coefficient in shallow water areas, thereby significantly improving the monitoring accuracy of water quality remote sensing in dynamic marine environments.

[0005] According to one aspect of the present invention, a method for correcting the diffuse attenuation coefficient of a water body based on the water surface lensing effect of a hyperspectral resolution lidar is provided. This method utilizes the water surface lensing effect generated by a hyperspectral resolution lidar to analyze the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy, as well as the pulse energy focusing caused by the water surface lensing effect, thereby correcting the diffuse attenuation coefficient of the hyperspectral resolution lidar in shallow water areas. The method includes: constructing a hyperspectral resolution lidar water surface lens model, simulating the dynamic water surface of the hyperspectral resolution lidar, tracking the refracted light rays of the hyperspectral resolution lidar, analyzing the energy focusing of the hyperspectral resolution lidar, and correcting the diffuse attenuation coefficient of the water body.

[0006] As a further technical solution, a high-spectral-resolution lidar water surface lens model is constructed as follows:

[0007]

[0008] Where, η q It is the quantum efficiency of the photodetector, η r It refers to the efficiency of the receiving system, E t It is the emitted energy of the lidar system, A r It refers to the size of the telescope aperture, R. h The orbital altitude is h, Planck's constant is h, v is the frequency of the photon, hv represents the energy of a single photon, and T is T. atm It is the atmospheric direct sunlight one-way transmittance, T water It is the one-way transmittance at the water-air interface, R. bot It is the water reflectance, exp(-2k lidar zsecθ vw The ) represents the two-way attenuation of the water body, including the lidar attenuation coefficient k. lidar Depth z and zenith angle θ vw n represents the number of beams focused on the same point. w It represents the refractive index of water.

[0009] As a further technical solution, simulating dynamic water surfaces using hyperspectral resolution lidar includes:

[0010] The dynamic changes in water surface slope are characterized by ECKV wave spectrum, and the dynamic water surface is simulated by fast Fourier transform, clarifying the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy.

[0011] As a further technical solution, tracking the refracted light from a high-spectral-resolution lidar includes:

[0012] For laser pulses that penetrate the water surface and enter the water body, Snell's law of refraction is used to track the beam to obtain the position where the laser beam reaches the bottom of the water.

[0013] As a further technical solution, the energy focusing of hyperspectral resolution lidar is analyzed, including:

[0014] For the laser pulse after ray tracing, the pulse focusing energy at each water depth position is calculated using a two-dimensional histogram statistical method.

[0015] As a further technical solution, correcting the water diffusion attenuation coefficient includes:

[0016] Based on the unique separation characteristics of water molecule and particle signals in hyperspectral resolution lidar, the diffuse attenuation coefficient of hyperspectral resolution lidar is corrected by utilizing the energy enhancement change caused by the water surface lens effect.

[0017] According to one aspect of the present invention, a water diffuse attenuation coefficient correction system based on the water surface lensing effect of hyperspectral resolution lidar is provided to implement the method described above. The system utilizes the water surface lensing effect generated by hyperspectral resolution lidar to analyze the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy, as well as the pulse energy focusing caused by the water surface lensing effect, thereby correcting the diffuse attenuation coefficient of hyperspectral resolution lidar in shallow water areas. The system includes: a hyperspectral resolution lidar water surface lensing model construction module, a hyperspectral resolution lidar dynamic water surface simulation module, a hyperspectral resolution lidar refracted ray tracing module, a hyperspectral resolution lidar energy focusing analysis module, and a water diffuse attenuation coefficient correction module.

[0018] According to one aspect of the present invention, a water diffuse attenuation coefficient correction device based on the water surface lensing effect of hyperspectral resolution lidar is provided, comprising a memory and a processor, wherein the memory stores program instructions to be executed by the processor, and the processor invokes the program instructions to execute the water diffuse attenuation coefficient correction method based on the water surface lensing effect of hyperspectral resolution lidar.

[0019] According to one aspect of the present invention, a non-transitory computer-readable storage medium is provided, the non-transitory computer-readable storage medium storing computer instructions that cause the computer to execute the water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lensing effect.

[0020] According to one aspect of the present invention, a computer program product is provided, comprising a computer program that, when executed by a processor, implements the water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lensing effect.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention characterizes the focusing phenomenon of pulse energy by constructing a water surface lensing effect model. It uses ECKV wave spectrum to simulate dynamic water surfaces and tracks laser pulses penetrating the water body based on the law of light refraction. A two-dimensional histogram is used to statistically analyze the focusing degree of pulse energy. Based on the unique molecular and particle separation characteristics of high-spectral-resolution lidar, the overestimated water diffuse attenuation coefficient in shallow water areas due to the water surface lensing effect is corrected. This invention provides a new solution for correcting the water diffuse attenuation coefficient in shallow sea areas, contributing to improved water quality monitoring accuracy in shallow water regions. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 A schematic flowchart of a water diffusion attenuation coefficient correction method based on the water surface lens effect of high spectral resolution lidar provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the water surface lens effect principle of a high spectral resolution lidar provided in an embodiment of the present invention.

[0026] Figure 3 This is a diagram showing the result of correcting the water diffuse attenuation coefficient of a high-spectral-resolution lidar using the method of the present invention, provided in an embodiment of the present invention. Detailed Implementation

[0027] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0029] The embodiment of this invention uses the hyperspectral resolution lidar carried during the SABOR voyage over the Atlantic Ocean to measure the lidar attenuation coefficient k. lidar As initial data, the attenuation coefficient k of lidar in shallow water areas is obtained through the water surface lensing effect. lidar Correction is performed. Currently, in most scenarios, the lidar attenuation coefficient k... lidar It is approximately equal to the water diffusion attenuation coefficient. Hyperspectral resolution lidar is based on the high spectral resolution characteristic to accurately distinguish and measure different scattering sources. It utilizes the difference in the spectral distribution of backscattered wavelengths between seawater molecules and suspended particles to effectively separate molecules and particles, thus effectively distinguishing the backscattered signals of water molecules and particles. The SABOR experiment was conducted by the R / V Endeavor research vessel in the Northwest Atlantic Ocean from July 18 to August 6, 2014. Specifically, the example matched hyperspectral resolution lidar data with actual measurement data (i.e., less than one day, less than 5 km distance), and three stations were selected during the experimental voyage for verification.

[0030] Please see Figure 1 The water diffuse attenuation coefficient correction method based on the water surface lensing effect of high spectral resolution lidar provided in this embodiment of the invention includes:

[0031] S1. Construction of a high-spectral-resolution lidar surface lens model;

[0032] S2. Dynamic water surface simulation using high-spectral-resolution lidar;

[0033] S3. High-spectral-resolution lidar refraction ray tracing;

[0034] S4. High spectral resolution lidar energy focusing analysis;

[0035] S5. Correction of water body diffusion attenuation coefficient.

[0036] S1 includes: constructing a theoretical model of the water surface lens effect suitable for high spectral resolution lidar.

[0037] Laser pulses can penetrate water surfaces and are scattered by molecules and particles in the water, with most of the energy returning to the laser in the incident direction. For calm water surfaces, the lidar signal intensity at depth z can be characterized as follows:

[0038] (1)

[0039] Where, η q It is the quantum efficiency of the photodetector, η r It refers to the efficiency of the receiving system, E t This is the emission energy of the lidar system (already considering the efficiency of the emission system), A r It refers to the size of the telescope aperture, R. h The orbital altitude is h, Planck's constant is h, v is the frequency of the photon, hv represents the energy of a single photon, and T is T. atm It is the atmospheric direct sunlight one-way transmittance, T water It is the one-way transmittance at the water-air interface, R. bot It is the water reflectance, which is related to the type of substrate on the seabed, exp(-2k lidar zsecθ vw The ) represents the two-way attenuation of the water body, including the lidar attenuation coefficient k. lidar Depth z, zenith angle θ vw .

[0040] A laser pulse penetrating a calm water surface will return to the laser along its original propagation path. However, emitted beams from different spatial locations may be focused to a single point by refraction through the dynamic water surface, a phenomenon known as the "water surface lensing effect." Figure 2 As shown. Due to the optical reciprocity theorem, the energy reflected from this focal point can return to the lidar receiving system through multiple paths, resulting in a significant enhancement of the underwater pulse energy. If n beams are simultaneously focused on the same point, the returned pulse energy is n times that without the focusing effect. In this case, the energy intensity equation can be expressed as:

[0041] (2)

[0042] S2 includes: characterizing the dynamic changes in water surface slope using ECKV wave spectrum, and simulating the dynamic water surface using fast Fourier transform.

[0043] The ECKV wave spectrum comprehensively considers the relationship between factors such as wind speed and surge, demonstrating the interaction between gravity waves and capillary waves, making it suitable for characterizing dynamic changes in water surface slope. This embodiment selects (L...) x, L y Within a range of 1m × 1m, (N) x , N y The grid is set to 2024×2024 points to ensure sufficient spatial resolution. The wave age Ω, a parameter reflecting wave growth, is set to 0.84, and the wind speed U... 10 Determined by actual collected data. (L) x , L y ) represents the area of ​​the simulated sea surface, (N) x , N y The value represents the number of grid points in each x and y direction when the simulated sea surface is gridded.

[0044] The basic form of the ECKV omnidirectional wave spectrum used to characterize the water surface can be expressed as follows:

[0045] (3)

[0046] Among them, B l It is the effect of gravity waves on the wave spectrum, B h It is the effect of capillary waves on the wave spectrum, both of which are affected by wave age Ω, wave number, and wind speed; k is the angular spatial frequency, which is determined by the wave number.

[0047] The ECKV directional spectrum, used to characterize the basic form of the water surface, can be expressed as follows:

[0048] (4)

[0049] Where G(k, φ) is a dimensionless propagation function, representing the propagation of waves of different frequencies relative to the downwind direction when φ=0, and S p It is an extended function that is affected by wave age, wave speed, and downwind direction, C s It is an available S p The normalization coefficient is calculated, where φ represents the direction of wave propagation, and φ=0 is equivalent to propagation with the wind.

[0050] A Fast Fourier Transform (FFT) is performed on the convolution of the ECKV wave spectrum and the directional spectrum. Based on the obtained wave amplitudes at different locations, a dynamic water surface simulation is completed. After simulation, the planar water surface coordinates z(x, y) at different locations reached by the laser pulse can be expressed as:

[0051] (5)

[0052] Where, k x k y φ represents the spatial frequency in the x and y directions, respectively. xy For the phase of a random wave, Ψ(k) x ,k yThe spectrum is two-dimensional and is determined by both S(k) and G(k, φ).

[0053] S3 includes: for laser pulses that penetrate the water surface and enter the water body, the Snell's law of refraction is used to track the beam in order to accurately obtain the position of the laser beam reaching the bottom of the water.

[0054] When a laser pulse propagates from air into water, it produces the Snell refraction effect. The change in the angle of refraction is determined by the difference in refractive index between the air and water interfaces. The law of refraction can be expressed as follows:

[0055] (6)

[0056] Where, n a θ represents the refractive index of air, θ1 represents the angle of incidence of light as it penetrates the water, and n w θ represents the refractive index of the water, and θ2 represents the angle of refraction of light after it passes through the water.

[0057] Based on the dynamic water surface simulated in Section S2, a non-uniform mesh discretization method is used to construct the three-dimensional microstructure features of the dynamic water surface. The direction of light propagation is analyzed by constructing a gradient tensor field, and the transmission coefficient of light passing through the air-water interface at the mesh point is statistically analyzed to accurately track the refraction trajectory of each light beam through the water body, which serves to subsequently calculate the focusing energy at different locations.

[0058] S4 includes: calculating the pulse focusing energy at each water depth location using a two-dimensional histogram statistical method for the laser pulse after ray tracing.

[0059] For each laser pulse penetrating the ECKV dynamic water surface model, the planar coordinates of the laser pulse at different water depths at each water surface grid point are first calculated using ray tracing. Then, a two-dimensional histogram is used to bin the coordinates on the receiving plane. The histogram results are normalized to statistically analyze the frequency distribution of pulse path return times at a given water depth.

[0060] The focused intensity of the pulse energy, i.e., the energy enhancement factor of each laser beam at a specific depth, can be expressed as:

[0061] (7)

[0062] Where I represents the focusing energy, i.e., the factor by which the energy is enhanced; Nor represents the pulse normalization result of the two-dimensional histogram.

[0063] S5 includes: using the enhanced hyperspectral resolution lidar pulse energy to correct the diffuse attenuation coefficient.

[0064] Given that hyperspectral resolution lidar can directly acquire independent water molecule and particle profile equations, the energy enhancement change A(z) caused by energy focusing has a similar effect on these two independent equations. Therefore, the water molecule profile S m ’ (z) and particle S p ’ (z) The lidar profile equation will become:

[0065] (8)

[0066] (9)

[0067] Among them, C m C p These are instrument-related parameters, β M β p These are the bulk backscattering coefficients for water molecules and suspended particles, respectively, at 180°.

[0068] Due to the diffuse attenuation coefficient k of the lidar lidar k can be obtained from the adjacent water depth range of the water molecule profile energy equation, and is obtained after energy focusing enhancement. lidar ' for

[0069] (10)

[0070] Therefore, the diffuse attenuation coefficient of the high spectral resolution lidar corrected by the water surface lens effect is:

[0071] (11)

[0072] In this embodiment, diffuse attenuation coefficient data from a high-spectral-resolution lidar system flying across the Atlantic Ocean is used. The correction result for this coefficient is as follows: Figure 3 As shown in the figure, the X-axis represents the diffuse attenuation coefficient, and the Y-axis represents different water depths. The lines in the figure represent the actual measurement results, the original diffuse attenuation coefficient value, and the corrected diffuse attenuation coefficient value, respectively. The MAPE values ​​before correction were 15.46%, 18.30%, and 15.96%, respectively, while the corrected values ​​were 5.07%, 4.17%, and 9.67%, respectively. The patented method significantly corrects the overestimation bias of the diffuse attenuation coefficient in shallow water areas caused by the water surface lensing effect, significantly improves the accuracy of diffuse attenuation coefficient inversion, and thus significantly improves the monitoring accuracy of water quality remote sensing in dynamic marine environments.

[0073] The implementation of the various embodiments of the present invention is based on programmed processing by a device with processor functionality. Therefore, in practical engineering, the technical solutions and functions of the various embodiments of the present invention are encapsulated into various modules. Based on this reality, and building upon the above embodiments, the embodiments of the present invention provide a water diffuse attenuation coefficient correction system based on the water surface lensing effect of a hyperspectral resolution lidar. This system is used to execute a water diffuse attenuation coefficient correction method based on the water surface lensing effect of a hyperspectral resolution lidar as described in the above method embodiments.

[0074] This system utilizes the water surface lensing effect generated by hyperspectral resolution lidar to analyze the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy, as well as the pulse energy focusing caused by the water surface lensing effect. It then corrects the diffuse attenuation coefficient of hyperspectral resolution lidar in shallow water areas. The system includes: a hyperspectral resolution lidar water surface lens model construction module, a hyperspectral resolution lidar dynamic water surface simulation module, a hyperspectral resolution lidar refracted ray tracing module, a hyperspectral resolution lidar energy focusing analysis module, and a water diffuse attenuation coefficient correction module.

[0075] The water diffuse attenuation coefficient correction system based on the water surface lensing effect of hyperspectral resolution lidar provided in this embodiment of the invention addresses the current situation where the pulse energy focusing phenomenon caused by the water surface lensing effect leads to an overestimation of the water diffuse attenuation coefficient in shallow water areas. By employing the aforementioned modules and utilizing the water surface lensing effect generated by hyperspectral resolution lidar, the system achieves accurate correction of the water diffuse attenuation coefficient in shallow water areas, thereby significantly improving the monitoring accuracy of water quality remote sensing in dynamic marine environments.

[0076] It should be noted that the system embodiments provided by the present invention are used not only to implement the methods in the above method embodiments, but also to implement the methods in other method embodiments provided by the present invention. The only difference is that corresponding functional modules are set. The principle is basically the same as that of the above system embodiments provided by the present invention. As long as those skilled in the art can improve the modules in the above system embodiments by referring to the specific technical solutions in other method embodiments and combining technical features to obtain corresponding technical means and technical solutions composed of these technical means, on the basis of the above system embodiments, and on the premise of ensuring the practicality of the technical solutions, they can obtain corresponding system-like embodiments for implementing the methods in other method-like embodiments.

[0077] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a water diffuse attenuation coefficient correction device based on the water surface lensing effect of hyperspectral resolution lidar, including a memory and a processor. The memory stores program instructions that are executed by the processor, and the processor calls the program instructions to execute the water diffuse attenuation coefficient correction method based on the water surface lensing effect of hyperspectral resolution lidar.

[0078] In embodiments of the present invention, the memory can be non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), or it can be volatile memory, such as random-access memory (RAM). Memory is any other medium capable of carrying or storing desired program code having an instruction or data structure form and accessible by a computer, but is not limited thereto. The memory in embodiments of the present invention can also be a circuit or any other device capable of implementing a storage function for storing program instructions and / or data.

[0079] In this embodiment of the invention, the processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components, capable of implementing or executing the methods, steps, and logic block diagrams disclosed in this embodiment of the invention. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in this embodiment of the invention can be directly manifested as being executed by a hardware processor, or executed by a combination of hardware and software modules within the processor.

[0080] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a non-transitory computer-readable storage medium storing computer instructions that cause the computer to execute the water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lens effect.

[0081] Based on the same inventive concept as the foregoing embodiments, this embodiment of the invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lens effect.

[0082] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0083] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0084] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0085] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0086] In summary, this invention discloses a method for correcting the water diffuse attenuation coefficient based on the water surface lensing effect of hyperspectral resolution lidar, belonging to the field of laser remote sensing. This invention characterizes the focusing phenomenon of pulse energy by constructing a water surface lensing effect model, uses ECKV wind and wave spectrum to simulate the dynamic water surface, and tracks the laser pulse penetrating the water body based on the law of light refraction, using a two-dimensional histogram to statistically analyze the degree of pulse energy focusing. Based on the unique molecular and particle separation characteristics of hyperspectral resolution lidar, the method corrects the overestimated water diffuse attenuation coefficient in shallow water areas due to the water surface lensing effect. This invention provides a new solution for correcting the water diffuse attenuation coefficient in shallow sea areas, helping to improve the accuracy of water quality monitoring in shallow water areas.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for correcting the water diffuse attenuation coefficient based on the water surface lensing effect of high spectral resolution lidar, characterized in that, This study utilizes the water surface lensing effect generated by hyperspectral resolution lidar to analyze the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy, as well as the pulse energy focusing caused by the water surface lensing effect. This leads to the correction of the diffuse attenuation coefficient of the hyperspectral resolution lidar in shallow water areas. The process includes: constructing a water surface lens model for the hyperspectral resolution lidar, simulating the dynamic water surface of the hyperspectral resolution lidar, tracking the refracted light rays of the hyperspectral resolution lidar, analyzing the energy focusing of the hyperspectral resolution lidar, and correcting the water diffuse attenuation coefficient. The high-spectral-resolution lidar water surface lens model is constructed as follows: ， in, η q It refers to the quantum efficiency of photodetectors. η r It's the efficiency of the receiving system. E t It is the emitted energy of the lidar system. A r It refers to the size of the telescope's aperture. R h It is the altitude of orbital flight. h It is Planck's constant. v It is the frequency of the photon. hv The energy representing a single photon T atm It is the one-way transmittance of direct atmospheric light. T water It is the one-way transmittance at the water-air interface. R bot It is the water reflectance, exp(-2 k lidar z sec θ vw This represents the two-way attenuation of the water body, including the lidar attenuation coefficient. k lidar ,depth z and zenith θ vw , n This indicates the number of beams focused on the same point. n w Indicates the refractive index of water; Simulation of dynamic water surface using hyperspectral resolution lidar includes: characterizing the dynamic change of water surface slope using ECKV wave spectrum, and simulating the dynamic water surface using fast Fourier transform, clarifying the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy. Analysis of energy focusing in hyperspectral resolution lidar includes: calculating the pulse focusing energy at each water depth location using a two-dimensional histogram statistical method for the laser pulse after ray tracing; Correcting the water diffuse attenuation coefficient includes: based on the unique separation characteristics of water molecule and particle signals in hyperspectral resolution lidar, using the energy enhancement change caused by the water surface lensing effect to correct the diffuse attenuation coefficient of hyperspectral resolution lidar.

2. The water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lensing effect according to claim 1, characterized in that, Tracking the refracted light from a high-spectral-resolution lidar, including: For laser pulses that penetrate the water surface and enter the water body, Snell's law of refraction is used to track the beam to obtain the position where the laser beam reaches the bottom of the water.

3. A water diffuse attenuation coefficient correction system based on the water surface lensing effect of high spectral resolution lidar, used to implement the method described in any one of claims 1-2, characterized in that, The system utilizes the water surface lensing effect generated by hyperspectral resolution lidar to analyze the quantitative mapping relationship between the dynamic slope change of the air-water interface and the underwater pulse energy, as well as the pulse energy focusing caused by the water surface lensing effect. This allows for the correction of the hyperspectral resolution lidar diffuse attenuation coefficient in shallow water areas. The system includes: a hyperspectral resolution lidar water surface lens model construction module, a hyperspectral resolution lidar dynamic water surface simulation module, a hyperspectral resolution lidar refracted ray tracing module, a hyperspectral resolution lidar energy focusing analysis module, and a water diffuse attenuation coefficient correction module.

4. A water diffuse attenuation coefficient correction device based on the water surface lensing effect of high spectral resolution lidar, characterized in that, The system includes a memory and a processor, wherein the memory stores program instructions that are executed by the processor, and the processor invokes the program instructions to execute the water diffuse attenuation coefficient correction method based on the water surface lensing effect of hyperspectral resolution lidar as described in any one of claims 1 to 2.

5. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to execute the water diffuse attenuation coefficient correction method based on the high spectral resolution lidar water surface lens effect as described in any one of claims 1 to 2.

6. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the water diffuse attenuation coefficient correction method based on the water surface lens effect of high spectral resolution lidar as described in any one of claims 1 to 2.

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