A method for retrieving ocean primary productivity based on airborne dual-wavelength lidar remote sensing data

Abstract

The present invention discloses a method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data. This method establishes a high-precision dual-wavelength water optical property inversion model based on the airborne dual-wavelength lidar remote sensing data, obtains a high-precision vertical profile of the ocean phytoplankton absorption coefficient, and inverts the vertical profile distribution of ocean primary productivity coupled with the high-precision phytoplankton absorption coefficient. The dual-wavelength ocean lidar, which uses one laser wavelength suitable for detecting nearshore waters and another for detecting offshore waters, improves the inversion accuracy of the maximum detection depth in near and offshore waters and the vertical profile distribution of primary productivity in typical waters, further enhancing the accuracy of the spatiotemporal evolution of the ocean carbon cycle and the observation capability of energy conversion in the upper ocean.

Description

Technical Field

[0001] The present invention relates to the field of ocean optical detection, and in particular to a method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data. Background Art

[0002] Assessments of marine primary productivity (MPP) are of great significance to global climate change and the ocean carbon cycle. Currently, research on MPP domestically and internationally relies primarily on observation platforms such as shipborne field measurements, biogeochemical buoys (BGC-Argo), and satellite-based ocean color remote sensing. However, shipborne field measurements are relatively time-consuming, labor-intensive, and have a limited observation range. BGC-Argo has a low resolution, and current passive ocean color remote sensing satellites can only observe the surface layer of the ocean. Consequently, MPP assessment models that couple this surface information to the ocean surface have low accuracy. Current single-wavelength ocean lidar remote sensing can obtain ocean water profile information, but only vertical profiles of chlorophyll concentration are derived from the backscattered signal of a single wavelength. Consequently, MPP assessment models that couple this vertical profile to chlorophyll concentration also have low accuracy. Consequently, existing observation platforms are unable to conduct large-scale, long-term, and high-precision assessments of MPP. Therefore, there is an urgent need to develop new ocean observation technologies to obtain high-precision vertical profile information and construct high-precision remote sensing inversion models of MPP vertical profiles. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention discloses a method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data. The lidar system uses lasers with emission wavelengths of λ1 and λ2 as the transmitting light source, and receives data in parallel and perpendicular polarization channels. The inversion method, based on the high-precision dual-wavelength vertical profiles of the water attenuation coefficient and the phytoplankton absorption coefficient, constructs an ocean primary productivity inversion model coupled with the vertical profile of the phytoplankton absorption coefficient to obtain the vertical profile distribution of ocean primary productivity along the lidar trajectory.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data.

[0006] If the airborne dual-wavelength laser radar is an airborne dual-wavelength Mie scattering laser radar, the method includes the following steps:

[0007] (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the ocean water is received by the telescope and divided into a parallel polarized Mie scattering channel and a vertical polarized Mie scattering channel. The received lidar backscattered signal is preprocessed by water signal extraction, averaging, denoising and distance correction.

[0008] (2) Assume that the volume scattering coefficient of ocean water at π radians is β π (λ,z) ​​and the laser radar attenuation coefficient K lidar (λ,z) ​​satisfies β π (λ,z)=AK lidar (λ,z) R , where λ is the laser wavelength emitted by the lidar, z is the detection depth, A is a related parameter, and R is the lidar backscatter extinction logarithm ratio; calculate the lidar attenuation coefficient, diffuse attenuation coefficient, and vertical profile of the lidar backscatter coefficient in the dual-wavelength λ1 and λ2 bands corresponding to the airborne dual-wavelength Mie scattering lidar;

[0009] (3) Calculate the vertical profile of phytoplankton absorption coefficient;

[0010] (4) Calculate the vertical profile distribution of ocean primary productivity along the lidar track;

[0011] If the airborne dual-wavelength laser radar is an airborne dual-wavelength high spectral resolution laser radar, the method includes the following steps:

[0012] (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the water is received by the telescope and divided into a dual-wavelength water Brillouin scattering channel and a dual-wavelength Mie scattering channel. The Brillouin scattering and Mie scattering channels are pre-processed to extract the water signal, average it, remove noise, and perform distance correction.

[0013] (2) Calculate the vertical profiles of the lidar attenuation coefficient and diffuse attenuation coefficient using the echo signal of the dual-wavelength Brillouin scattering channel, and further calculate the vertical profile of the lidar backscattering coefficient using the echo signal of the dual-wavelength Mie scattering channel;

[0014] (3) The vertical profile of the phytoplankton absorption coefficient is calculated and finally the vertical profile distribution of the ocean primary productivity along the lidar track is inverted.

[0015] Furthermore, if the airborne dual-wavelength laser radar is an airborne dual-wavelength Mie scattering laser radar, the specific implementation process of steps (2) to (4) is as follows:

[0016] Take the depth of a certain boundary value detected by the laser radar as z B , then the laser radar attenuation coefficient at wavelength λ1 is expressed as:

[0017]

[0018] The laser radar attenuation coefficient at wavelength λ2 is expressed as:

[0019]

[0020] Where λ1 and λ2 are both laser wavelengths;

[0021] Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient K is further obtained. d (λ1,z) and K d (λ2,z);

[0022] Calculate the volume scattering coefficient β of a dual-wavelength lidar with an angle of π radians π (λ1,z) and β π (λ2,z):

[0023] Assuming that the volume scattering coefficient of ocean water at π radians is the sum of the uniform water optical parameters that do not vary with depth and the inhomogeneous water optical parameters that vary with depth, then:

[0024] The volume scattering coefficient β of ocean water at λ1 wavelength π radians π (λ1,z) is expressed as:

[0025]

[0026] Where S(λ1,z) is the total lidar echo signal generated by the λ1 laser, S h (λ1,z) is the lidar echo signal generated by the λ1 laser in the uniform water body, is the volume scattering coefficient of π radians produced by λ1 laser in uniform water;

[0027] The volume scattering coefficient β of ocean water at λ2 wavelength π radians π (λ2,z) is expressed as:

[0028]

[0029] Where S(λ2,z) is the total lidar echo signal generated by the λ2 laser, S h (λ2,z) is the lidar echo signal generated by the λ2 laser in the uniform water body, is the volume scattering coefficient of π radians produced by λ2 laser in uniform water;

[0030] Calculate the lidar backscatter coefficient based on the volume scattering coefficient of ocean water in the λ1 and λ2 bands at π radians and

[0031]

[0032] Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, b bw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2;

[0033] Calculate the vertical profile of the dual-wavelength total water absorption coefficient along the lidar track and

[0034]

[0035] Calculate vertical profiles of phytoplankton absorption coefficients along lidar tracks

[0036]

[0037] Among them, a w (λ1,z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2,z) is the absorption coefficient of pure seawater at wavelength λ2, a dg (λ1,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients;

[0038] Calculate the vertical profile of ocean primary productivity (PP) along the lidar track lidar (z):

[0039]

[0040] where φ is the quantum yield of phytoplankton photosynthesis and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z.

[0041] Furthermore, if the airborne dual-wavelength laser radar is an airborne dual-wavelength high spectral resolution laser radar, the corresponding steps (2) to (3) are specifically implemented as follows:

[0042] Based on the seawater Brillouin scattering echo signal S b (λ,z), calculate the lidar attenuation coefficient The laser radar attenuation coefficient at wavelength λ1 is expressed as:

[0043]

[0044] The laser radar attenuation coefficient at wavelength λ2 is expressed as:

[0045]

[0046] in, is the Brillouin backscattering coefficient of seawater at λ1, is the Brillouin backscattering coefficient of seawater at λ2, n is the refractive index of seawater, and H is the flight altitude of the airborne lidar;

[0047] Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient is further obtained and

[0048] Based on the attenuation coefficient of dual-wavelength laser radar and The volume scattering coefficient of the dual-wavelength LiDAR at π radians is further obtained by using the airborne dual-wavelength Mie scattering LiDAR echo signal. and

[0049] Volume scattering coefficient of dual-wavelength ocean water based on π radians and Calculating the backscatter coefficient of dual-wavelength lidar and

[0050]

[0051] Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, b bw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2;

[0052] Calculate the vertical profile of the dual-wavelength total water absorption coefficient along the lidar track and

[0053]

[0054] Calculate vertical profiles of phytoplankton absorption coefficients along lidar tracks

[0055]

[0056] Among them, a w (λ1,z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2,z) is the absorption coefficient of pure seawater at wavelength λ2, a dg(λ1,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients;

[0057] Calculate the vertical profile of ocean primary productivity (PP) along the lidar track HSRL (z):

[0058]

[0059] where φ is the quantum yield of phytoplankton photosynthesis and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z.

[0060] Furthermore, the two laser wavelengths of the airborne dual-wavelength lidar are 532nm and 486nm respectively.

[0061] Furthermore, the value of λ3 is 440 nm.

[0062] The present invention's method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data utilizes airborne dual-wavelength lidar remote sensing data to obtain high-precision dual-wavelength optical vertical profiles of water bodies. This method then inverts the vertical profile distribution of ocean primary productivity coupled with high-precision vertical profiles of phytoplankton absorption coefficients. Compared to passive satellite remote sensing data and single-wavelength lidar remote sensing data, the method offers the following benefits:

[0063] (1) The method of inverting ocean primary productivity based on dual-wavelength ocean lidar remote sensing data of the present invention can obtain a high-precision vertical profile of phytoplankton absorption coefficient, and thus obtain a high-precision vertical profile distribution of ocean primary productivity;

[0064] (2) The present invention is a dual-wavelength detection, in which one laser wavelength is suitable for detecting nearshore waters, and the other laser wavelength is suitable for detecting offshore waters. The dual-wavelength ocean lidar improves the maximum detection depth of near and far seas and the inversion accuracy of the vertical profile distribution of primary productivity in typical sea areas, and further improves the accuracy of the spatiotemporal evolution of the ocean carbon cycle and the observation capability of energy conversion in the upper ocean. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 Flowchart of the inversion method of the present invention.

[0066] Figure 2 This is the vertical profile result of the inverted dual-wavelength diffuse attenuation coefficient.

[0067] Figure 3 This is the vertical profile result of the inverted phytoplankton absorption coefficient. DETAILED DESCRIPTION

[0068] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become more apparent. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0069] Based on dual-wavelength ocean lidar remote sensing data, the present invention can obtain dual-wavelength vertical profile information of seawater optical properties, further obtain the vertical profile of phytoplankton plant absorption coefficient, and construct an ocean primary productivity assessment model coupled with the vertical profile of phytoplankton absorption coefficient to improve the assessment accuracy of ocean primary productivity.

[0070] like Figure 1 As shown, the method of inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data of the present invention specifically includes the following steps:

[0071] If the airborne dual-wavelength lidar is an airborne dual-wavelength Mie scattering lidar, and the emitted laser wavelengths are λ1 and λ2 respectively, the method for inverting ocean primary productivity includes the following steps:

[0072] (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the ocean water is received by the telescope and divided into a parallel polarized Mie scattering channel and a vertical polarized Mie scattering channel. The received airborne dual-wavelength Mie scattering lidar backscattered signal is subjected to water signal extraction, averaging, denoising and distance correction preprocessing.

[0073] (2) Calculation of the attenuation coefficient K of the dual-wavelength lidar lidar (λ1,z) and K lidar (λ2,z):

[0074] Assume that the volume scattering coefficient β of ocean water at π radians is π (λ,z) ​​and the laser radar attenuation coefficient K lidar (λ,z) ​​satisfies:

[0075] β π (λ,z)=AK lidar (λ,z) R

[0076] Where S(λ,z) ​​is the laser radar echo signal, z is the detection depth, A is the related parameter, R is the laser radar backscatter extinction logarithm ratio; λ is the laser wavelength emitted by the laser radar;

[0077] Take the depth of a certain boundary value detected by the laser radar as z B , then the laser radar attenuation coefficient at wavelength λ1 is expressed as:

[0078]

[0079] The laser radar attenuation coefficient at wavelength λ2 is expressed as:

[0080]

[0081] Wherein, λ1 and λ2 are both laser wavelengths; preferably, λ1 is 532 nm and λ2 is 486 nm.

[0082] (3) Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient K can be further obtained. d (λ1,z) and K d (λ2,z).

[0083] (4) Calculate the volume scattering coefficient β of the dual-wavelength lidar π radians π (λ1,z) and β π (λ2,z):

[0084] Assuming that the volume scattering coefficient of ocean water at π radians is the sum of the uniform water optical parameters that do not vary with depth and the inhomogeneous water optical parameters that vary with depth, then:

[0085] The volume scattering coefficient β of ocean water at λ1 wavelength π radians π (λ1,z) is expressed as:

[0086]

[0087] Where S(λ1,z) is the total lidar echo signal generated by the λ1 laser, S h (λ1,z) is the lidar echo signal generated by the λ1 laser in the uniform water body, is the volume scattering coefficient of π radians produced by λ1 laser in uniform water;

[0088] The volume scattering coefficient β of ocean water at λ2 wavelength π radians π (λ2,z) is expressed as:

[0089]

[0090] Where S(λ2,z) is the total lidar echo signal generated by the λ2 laser, S h (λ2,z) is the lidar echo signal generated by the λ2 laser in the uniform water body, is the volume scattering coefficient of π radians generated by λ2 laser in uniform water.

[0091] (5) Calculate the backscattering coefficient of the lidar based on the volume scattering coefficient of the ocean water body of π radians in the λ1 and λ2 bands and

[0092]

[0093] Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, b bw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2.

[0094] (6) Calculate the vertical profile of the dual-wavelength water total absorption coefficient along the lidar trajectory and

[0095]

[0096] (7) Calculate the vertical profile of phytoplankton absorption coefficient along the lidar track

[0097]

[0098] Among them, a w (λ1,z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2,z) is the absorption coefficient of pure seawater at wavelength λ2, a dg (λ1,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, and a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients.

[0099] (8) Calculate the vertical profile of ocean primary productivity (PP) along the lidar track lidar (z):

[0100]

[0101] Where φ is the quantum yield of phytoplankton photosynthesis, and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z. Preferably, λ3 is 440 nm.

[0102] If the airborne dual-wavelength lidar is an airborne dual-wavelength high-spectral-resolution lidar, and the emitted laser wavelengths are λ1 and λ2 respectively, the method for inverting ocean primary productivity includes the following steps:

[0103] (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the water is received by the telescope and divided into a dual-wavelength water Brillouin scattering channel and a dual-wavelength Mie scattering channel. The Brillouin scattering and Mie scattering channels are pre-processed to extract the water signal, average it, remove noise, and perform distance correction.

[0104] (2) Calculation of the attenuation coefficient of dual-wavelength lidar and

[0105] Based on the seawater Brillouin scattering echo signal S b (λ,z), calculate the lidar attenuation coefficient The laser radar attenuation coefficient at wavelength λ1 is expressed as:

[0106]

[0107] The laser radar attenuation coefficient at wavelength λ2 is expressed as:

[0108]

[0109] in, is the Brillouin backscattering coefficient of seawater at λ1, is the Brillouin backscattering coefficient of seawater at λ2, n is the refractive index of seawater, and H is the flight altitude of the airborne lidar. Wherein, λ1 and λ2 are both laser wavelengths; preferably, λ1 is 532 nm and λ2 is 486 nm.

[0110] (3) Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient can be further obtained and

[0111] (4) Based on the attenuation coefficient of dual-wavelength lidar and The volume scattering coefficient of the dual-wavelength LiDAR at π radians can be further obtained by using the airborne dual-wavelength Mie scattering LiDAR echo signal. and

[0112] (5) Volume scattering coefficient based on dual-wavelength ocean water π radians and Calculating the backscatter coefficient of dual-wavelength lidar and

[0113]

[0114] Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, bbw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2.

[0115] (6) Calculate the vertical profile of the dual-wavelength water total absorption coefficient along the lidar trajectory and

[0116]

[0117] (7) Calculate the vertical profile of phytoplankton absorption coefficient along the lidar track

[0118]

[0119] Among them, a w (λ1,z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2,z) is the absorption coefficient of pure seawater at wavelength λ2, a dg (λ1,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2,z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, and a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients.

[0120] (8) Calculate the vertical profile of ocean primary productivity (PP) along the lidar track HSRL (z):

[0121]

[0122] Where φ is the quantum yield of phytoplankton photosynthesis, and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z. Preferably, λ3 is 440 nm.

[0123] The vertical profile distribution of marine primary productivity obtained based on the above calculations can promote research on the driving mechanism of the vertical profile distribution of marine primary productivity, marine ecological environment monitoring, marine carbon cycle and sustainable utilization of biological resources.

[0124] Figure 2 This is the vertical profile result of dual-wavelength water optical properties obtained by the method proposed in this invention to invert ocean primary productivity based on airborne dual-wavelength Mie scattering lidar remote sensing data. From the figure, it can be seen that the maximum detection depth of the dual-wavelength Mie scattering lidar for the upper ocean can reach 100m, and the vertical profile distribution of the dual-wavelength water diffuse attenuation coefficient can be clearly seen.

[0125] Figure 3This is the result of the marine phytoplankton absorption coefficient obtained by the method proposed in this invention for inverting marine primary productivity based on airborne dual-wavelength Mie scattering lidar remote sensing data. The vertical profile distribution of the marine phytoplankton absorption coefficient can be clearly seen from the figure.

[0126] When using airborne dual-wavelength high-spectral resolution lidar remote sensing data to invert ocean primary productivity, the dual-wavelength Brillouin scattering channel and Mie scattering channel lidar backscattering signals are utilized to solve the problem of solving two unknowns in one equation, and obtain dual-wavelength high-precision vertical profile distribution of water optical properties, and further obtain high-precision vertical profile of marine phytoplankton absorption coefficient, so as to make high-precision assessment of vertical profile of ocean primary productivity; on the other hand, the dual-wavelength high-spectral resolution lidar system uses blue-green wavelengths, which are the optimal bands for near- and far-sea detection, greatly improving the maximum detection depth of the ocean.

[0127] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art will still be able to modify the technical solutions described in the foregoing examples or substitute equivalents for some of the technical features therein. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the invention shall be included within the scope of protection of the invention.

Claims

1. A method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data, characterized in that: If the airborne dual-wavelength laser radar is an airborne dual-wavelength Mie scattering laser radar, the method includes the following steps: (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the ocean water is received by the telescope and divided into a parallel polarized Mie scattering channel and a vertical polarized Mie scattering channel. The received lidar backscattered signal is preprocessed by water signal extraction, averaging, denoising and distance correction. (2) Assume that the volume scattering coefficient of ocean water at π radians is β π (λ,z) ​​and the laser radar attenuation coefficient K lidar (λ, z) satisfies β π (λ, z) = AK lidar (λ,z) R , where λ is the laser wavelength emitted by the lidar, z is the detection depth, A is a related parameter, and R is the lidar backscatter extinction logarithm ratio; calculate the lidar attenuation coefficient, diffuse attenuation coefficient, and vertical profile of the lidar backscatter coefficient in the dual-wavelength λ1 and λ2 bands corresponding to the airborne dual-wavelength Mie scattering lidar; (3) Calculate the vertical profile of phytoplankton absorption coefficient; (4) Calculate the vertical profile distribution of ocean primary productivity along the lidar track; If the airborne dual-wavelength laser radar is an airborne dual-wavelength high spectral resolution laser radar, the method includes the following steps: (1) The laser pulse passes through the surface of the ocean water and is incident into the ocean water. The backscattered signal generated in the water is received by the telescope and divided into a dual-wavelength water Brillouin scattering channel and a dual-wavelength Mie scattering channel. The Brillouin scattering and Mie scattering channels are pre-processed to extract the water signal, average it, remove noise, and perform distance correction. (2) Calculate the vertical profiles of the lidar attenuation coefficient and diffuse attenuation coefficient using the echo signal of the dual-wavelength Brillouin scattering channel, and further calculate the vertical profile of the lidar backscattering coefficient using the echo signal of the dual-wavelength Mie scattering channel; (3) The vertical profile of the phytoplankton absorption coefficient is calculated and finally the vertical profile distribution of the ocean primary productivity along the lidar track is inverted.

2. The method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data according to claim 1, characterized in that: If the airborne dual-wavelength laser radar is an airborne dual-wavelength Mie scattering laser radar, the specific implementation process of steps (2) to (4) is as follows: Take the depth of a certain boundary value detected by the laser radar as z B , then the laser radar attenuation coefficient at wavelength λ1 is expressed as: The laser radar attenuation coefficient at wavelength λ2 is expressed as: Where λ1 and λ2 are both laser wavelengths; Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient K is further obtained. d (λ1, z) and K d (λ2, z); Calculate the volume scattering coefficient β of a dual-wavelength lidar with an angle of π radians π (λ1, z) and β π (λ2, z): Assuming that the volume scattering coefficient of ocean water at π radians is the sum of the uniform water optical parameters that do not vary with depth and the inhomogeneous water optical parameters that vary with depth, then: The volume scattering coefficient β of ocean water at λ1 wavelength π radians π (λ1, z) is expressed as: Where S(λ1, z) is the total lidar echo signal generated by the λ1 laser, S h (λ1, z) is the lidar echo signal generated by the λ1 laser in the uniform water body, is the volume scattering coefficient of π radians produced by λ1 laser in uniform water; The volume scattering coefficient β of ocean water at λ2 wavelength π radians π (λ2, z) is expressed as: Where S(λ2, z) is the total lidar echo signal generated by the λ2 laser, S h (λ2, z) is the lidar echo signal generated by the λ2 laser in the uniform water body, is the volume scattering coefficient of π radians produced by λ2 laser in uniform water; Calculate the lidar backscatter coefficient based on the volume scattering coefficient of ocean water in the λ1 and λ2 bands at π radians and Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, b bw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2; Calculate the vertical profile of the dual-wavelength total water absorption coefficient along the lidar track and Calculate vertical profiles of phytoplankton absorption coefficients along lidar tracks Among them, a w (λ1, z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2, z) is the absorption coefficient of pure seawater at wavelength λ2, a dg (λ1, z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2, z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients; Calculate the vertical profile of ocean primary productivity (PP) along the lidar track lidar (z): where φ is the quantum yield of phytoplankton photosynthesis and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z.

3. The method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data according to claim 1, characterized in that: If the airborne dual-wavelength laser radar is an airborne dual-wavelength high-spectral-resolution laser radar, the corresponding steps (2) to (3) are specifically implemented as follows: Based on the seawater Brillouin scattering echo signal S b (λ, z), calculate the lidar attenuation coefficient The laser radar attenuation coefficient at wavelength λ1 is expressed as: The laser radar attenuation coefficient at wavelength λ2 is expressed as: in, is the Brillouin backscattering coefficient of seawater at λ1, is the Brillouin backscattering coefficient of seawater at λ2, n is the refractive index of seawater, and H is the flight altitude of the airborne lidar; Based on the lidar attenuation coefficients of the λ1 and λ2 bands, the diffuse attenuation coefficient is further obtained and Based on the attenuation coefficient of dual-wavelength laser radar and The volume scattering coefficient of the dual-wavelength LiDAR at π radians is further obtained by using the airborne dual-wavelength Mie scattering LiDAR echo signal. and Volume scattering coefficient of dual-wavelength ocean water based on π radians and Calculating the backscatter coefficient of dual-wavelength lidar )and Where χ is the conversion factor between the volume scattering coefficient of ocean water at π radians and the particle backscattering coefficient, b bw (λ1) is the backscattering coefficient of pure seawater at wavelength λ1, b bw (λ2) is the backscattering coefficient of pure seawater at wavelength λ2; Calculate the vertical profile of the dual-wavelength total water absorption coefficient along the lidar track and Calculate vertical profiles of phytoplankton absorption coefficients along lidar tracks Among them, a w (λ1, z) is the absorption coefficient of pure seawater at wavelength λ1, a w (λ2, z) is the absorption coefficient of pure seawater at wavelength λ2, a dg (λ1, z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ1, a dg (λ2, z) is the absorption coefficient of debris and colored soluble organic matter at wavelength λ2, a0(λ1), a1(λ1), b0(λ2), and b1(λ2) are correlation coefficients; Calculate the vertical profile of ocean primary productivity (PP) along the lidar track HSRL (z): where φ is the quantum yield of phytoplankton photosynthesis and E(λ,z) ​​is the solar irradiance at wavelength λ and depth z.

4. The method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data according to claim 1, characterized in that: The two laser wavelengths of the airborne dual-wavelength laser radar are 532nm and 486nm respectively.

5. The method for inverting ocean primary productivity based on airborne dual-wavelength lidar remote sensing data according to claim 1, characterized in that: The value of λ3 is 440nm.

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