A method for calculating high-resolution atmospheric radiative transfer of greenhouse gases

Abstract

This invention discloses a high-resolution atmospheric radiative transfer calculation method for greenhouse gases. It simultaneously calculates molecular absorption, particulate scattering, and surface reflection at high spectral resolution, including: acquiring atmospheric state parameters; calculating Doppler broadening, collisional broadening, and the combined broadening resulting from their interaction; calculating the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption; calculating the scattering coefficient and extinction coefficient of particulate matter; obtaining global surface reflectance by combining land and ocean reflectance; simulating the absorption of atmospheric molecules during radiative transfer, and the attenuation of clouds and aerosols during radiative transfer; and obtaining the radiant brightness of the top of the atmosphere by combining the global surface reflectance simulation. Compared to existing atmospheric radiative transfer models, this method has advantages such as high accuracy and high resolution, is applicable to multiple scenarios, and lays the foundation for satellite payload forward modeling and inversion algorithm development.

Description

Technical Field

[0001] This invention belongs to the field of atmospheric environment remote sensing monitoring technology, specifically relating to a method for calculating atmospheric high-resolution radiative transfer of greenhouse gases. Background Technology

[0002] With increasing global industrialization and energy consumption, the concentrations of typical greenhouse gases such as carbon dioxide and methane in the Earth's atmosphere are rising continuously, leading to global climate change and environmental problems. Greenhouse gas emissions exacerbate climate and environmental issues; however, our understanding of greenhouse gases and their spatiotemporal distribution remains significantly inadequate, hindering the development of carbon-climate interaction models and accurate climate change predictions. Therefore, high-precision and high-accuracy greenhouse gas monitoring is of great scientific significance for research on climate change and the global carbon cycle. Furthermore, high-quality greenhouse gas observation data can be further processed through inversion models to obtain near-surface carbon fluxes and anthropogenic carbon emissions, providing high-quality data and a theoretical foundation for global carbon inventory, government climate mitigation policy formulation, and carbon neutrality and carbon peaking pathway planning, thus possessing immense social value.

[0003] Therefore, in order to better understand and monitor the carbon cycle in the atmosphere, scientists have developed atmospheric carbon monitoring satellites. The satellite payload system is novel and complex, necessitating full-link simulation of the payload before hardware development to conduct error analysis and parameter scheme verification.

[0004] The radiative transfer process of sunlight or laser light in the atmosphere is a crucial component of end-to-end simulation. This transfer involves interaction with atmospheric molecules and aerosols. During this process, sunlight or laser light is affected by absorption and scattering from atmospheric molecules and aerosols, resulting in energy changes and conversions. This process causes varying degrees of enhancement and reduction in the radiation spectrum received by satellite spectrometers. The radiative transfer process mainly includes molecular absorption, scattering by particulate matter (clouds and aerosols), and reflection from the Earth's surface. Existing atmospheric radiative transfer models can be categorized into three types based on spectral resolution: low-resolution models (>5 cm⁻¹). -1 ), medium resolution model (1cm) -1 ~5cm -1 ) and high-resolution models (<1cm) -1 The biggest difference between atmospheric radiative transfer models lies in the solution methods for the radiative transfer equations; different models have different spectral resolutions. The applicability of atmospheric radiative transfer models is mainly constrained by their spectral resolution.

[0005] Existing atmospheric radiative transfer models cannot meet the full-link simulation requirements of satellite payloads. Current low-to-medium resolution atmospheric radiative transfer models consider both molecular absorption and aerosol scattering, while high-resolution radiative transfer models only consider molecular absorption. For satellite payload radiative transfer simulations, both molecular absorption and aerosol scattering must be considered simultaneously. Furthermore, taking an integral path differential absorption lidar as an example, its linewidth is 50 MHz, corresponding to a required spectral resolution of 0.017 cm⁻¹. -1 Therefore, from the perspective of spectral resolution, only high spectral resolution models can meet the simulation requirements of integral path differential absorption lidar.

[0006] Chinese patent application CN119000616A, targeting the Fengyun satellite spectral imager, develops an atmospheric correction method, device, medium, and product based on the 6S radiative transfer mode. The method involves generating target coefficients using the 6S radiative transfer mode and the spectral response function of MERSI; constructing a lookup table; applying an interpolation algorithm to obtain matching data values ​​for the second parameter corresponding to each pixel in the target MERSI observation data; determining the target coefficients for each pixel in the target MERSI observation data from the lookup table; obtaining the corrected reflectance of each pixel using the 6S radiative transfer mode; and correcting the visible light channel true-color quick view based on the corrected reflectance of each pixel to obtain a corrected true-color composite image. This method enables atmospheric correction of MERSI wide-swath global imagery.

[0007] In existing technologies, 6S and others simultaneously consider radiative transfer from molecular absorption and aerosol scattering, but the spectral resolution of the model is low, which is difficult to meet the high spectral resolution simulation requirements of satellite passive payloads. Therefore, it is necessary to model the atmospheric top radiative transfer simulation calculation for greenhouse gas passive payloads in order to evaluate the performance of greenhouse gas passive payloads. Summary of the Invention

[0008] In view of the above, the purpose of this invention is to provide a high-resolution atmospheric radiative transfer calculation method for greenhouse gases. This method simultaneously calculates molecular absorption, particulate scattering, and surface reflection at high spectral resolution, simulating the radiance of the top of the atmosphere. It achieves high accuracy and high resolution calculations, is applicable to multiple scenarios, and can be used to conduct target gas radiative transfer simulations under different scenarios, laying the foundation for satellite payload forward modeling and inversion algorithm development.

[0009] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0010] This invention provides a method for calculating high-resolution atmospheric radiative transfer of greenhouse gases, comprising the following steps:

[0011] Obtain atmospheric state parameters;

[0012] Calculate the Doppler broadening caused by the Doppler frequency shift generated by molecular motion in the atmosphere, and calculate the collision broadening caused by the collisions between molecules, atoms, and ions in the atmosphere;

[0013] The combined broadening of atmospheric molecular spectral lines under the combined effects of Doppler broadening and collisional broadening is calculated. Based on the combined broadening, the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption are calculated.

[0014] The optical properties of particulate matter, including scattering coefficient and extinction coefficient, are calculated based on Mie scattering theory.

[0015] Global surface reflectance is obtained by combining land reflectance and ocean reflectance;

[0016] The absorption of atmospheric molecules during radiative transfer and the attenuation of clouds and aerosols during radiative transfer are simulated, and the radiance of the top of the atmosphere is obtained by combining the simulation of global surface reflectance.

[0017] Specifically, the acquisition of atmospheric state parameters includes:

[0018] Acquire atmospheric state parameters from the ECMWF ERA5 dataset, which includes basic information on atmospheric temperature, humidity, pressure profiles, and atmospheric molecular concentration profiles.

[0019] The distribution information of cloud-aerosol parameter profiles in the atmosphere obtained by CALIPSO satellite measurements is used as atmospheric state parameters. The distribution information of cloud-aerosol parameter profiles includes cloud and aerosol types, extinction coefficient profiles, and layered optical thickness.

[0020] Specifically, the calculation of the Doppler broadening caused by the Doppler frequency shift resulting from molecular motion in the atmosphere includes:

[0021] Considering the spectral broadening caused by the Doppler effect due to molecular motion, i.e., Doppler broadening, whose line shape function is Gaussian, the formula for calculating the half-maximum and half-width of the Doppler-broadened spectral line at a specific temperature T is:

[0022]

[0023] Where, α D (T) represents the full width at half maximum (FWHM) of the Doppler broadened spectral line, v ij The wavenumber represents the spectral line transition in vacuum, i represents the isotope number of the gas molecule, j represents the discrete characteristic spectral wavenumber of the gas molecule, c represents the speed of light in vacuum, M represents the mass of a single molecule, and N represents the mass of a single molecule. A Denotes Avogadro's constant, and k denotes Boltzmann's constant;

[0024] The Gaussian line shape function for Doppler broadening is:

[0025]

[0026] Among them, f G (v,v ij ,p,T) represents Doppler broadening, and v represents the wavenumber at any position.

[0027] Specifically, the calculation of collision broadening caused by collisions between molecules, atoms, and ions includes:

[0028] Considering the irregular phase abrupt changes in the radiation wave train caused by collisions between molecules, atoms, and ions in the atmosphere, i.e., collision broadening, whose line shape function is Lorentz-type, the formula for calculating the half-maximum and half-width of the collision broadened spectral line under specific temperature T and pressure p is:

[0029]

[0030] Where γ(p,T) represents the full width at half maximum (FWHM) of the collision broadening spectral line, and T ref Indicates the reference temperature, n air γ represents the temperature coefficient of the air broadening half-width function. air γ represents the half-height and half-width of the air at standard atmospheric conditions. self p represents the self-expanding half-height and half-width. self p represents the partial pressure of gas molecules in the atmosphere. ref Indicates the reference standard atmosphere;

[0031] The Lorentz line shape function for collision widening is:

[0032]

[0033] Among them, f D (v,v ij ,p,T) represents collision widening, δ(p ref () indicates the frequency offset under the reference standard atmospheric pressure.

[0034] Specifically, the comprehensive broadening of atmospheric molecular spectral lines under the combined effect of Doppler broadening and collisional broadening includes:

[0035] The formula for calculating the overall broadening of atmospheric molecular spectral lines is:

[0036]

[0037] Where, f(v,v) ij (p,T) represents the overall broadening of atmospheric molecular spectral lines, f G (v,v ij,p,T) represents Doppler broadening, f D (v,v ij (p,T) indicates collision widening. This indicates the Voigt convolution operation.

[0038] Specifically, the calculation of the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption based on comprehensive broadening includes:

[0039] The formula for calculating the absorption coefficient of atmospheric molecules is:

[0040] k ij (v,p,T)=S ij (T)f(v,v ij ,p,T)

[0041] Where, k ij (v,p,T) represents the absorption coefficient of atmospheric molecules, f(v,v) ij (p,T) represents the overall broadening, S ij (T) represents the spectral line intensity of the high-resolution atmospheric molecular absorption spectral database;

[0042] The formula for calculating the total optical thickness of atmospheric molecules is:

[0043]

[0044] Where, τ ij (v,r) represents the total optical thickness of atmospheric molecules at wavenumber v and altitude r, X gas (r) represents the atmospheric molecular number density at the specified location, k ij (v,r) represents the atmospheric molecular absorption coefficient, the value of which is affected by wavenumber v and altitude r, where r grad and r TOA These represent the altitudes of the Earth's surface and the top of the atmosphere, respectively.

[0045] The formula for calculating the light intensity attenuation caused by absorption is:

[0046] I(v)=I0exp(-τ)

[0047] Where I(v) represents the light intensity attenuation at wavenumber v, I0 represents the incident light intensity of sunlight, and τ represents the optical thickness of the molecule.

[0048] Specifically, the optical characteristic parameters of the particulate matter, including the scattering coefficient and extinction coefficient, calculated based on Mie scattering theory, include:

[0049] According to Mie scattering theory, the scattering coefficient and extinction coefficient of particulate matter are calculated to describe the interaction between particulate matter and sunlight. The calculation formula is as follows:

[0050]

[0051] Where α represents the extinction coefficient, β represents the scattering coefficient, N0 represents the aerosol particle number density, and r m The median radius of the aerosol number concentration spectral distribution is represented by σ, where σ represents r. m standard deviation, Q ext Q represents the extinction efficiency factor of a single particulate matter particle. back The backscattering efficiency factor of a single particle is represented by r, where r represents the particle radius. max r represents the maximum radius of the particulate matter. min This represents the minimum radius of the particulate matter.

[0052] Specifically, the combined land and ocean reflectance yields the global surface reflectance, including:

[0053] Land reflectance was obtained using the MODIS MCD43C4 dataset;

[0054] Ocean reflectivity is measured by Fresnel reflection and the scattering contribution of the ocean white cap, and the formula is as follows:

[0055] R sea =(1-W)R s +WR f

[0056] Among them, R sea R represents ocean reflectivity. s R represents the Fresnel reflectance of the sea surface. f denoted by , where W represents the reflectance of the ocean white cap, and W represents the coverage of the ocean white cap.

[0057] Specifically, the simulation of the absorption of atmospheric molecules during radiative transfer and the attenuation of clouds and aerosols during radiative transfer includes:

[0058] The LBLRTM radiative transfer model with line-by-line integration was used to simulate the absorption of atmospheric molecules during radiative transfer, while the DISORT radiative transfer model with discrete ordinates was used to simulate the attenuation of clouds and aerosols during radiative transfer.

[0059] Specifically, the method of obtaining the radiance of the top of the atmosphere by combining global surface reflectance simulation includes:

[0060] By coupling the radiative transfer model LBLRTM and the radiative transfer model DISORT, the absorption and scattering of molecules and particles during radiative transfer are accurately simulated, and the radiance of the top of the atmosphere is obtained by combining the simulation of global surface reflectance.

[0061] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0062] (1) The atmospheric high-resolution radiative transfer calculation method for greenhouse gases provided by the present invention can simultaneously perform molecular absorption and particulate scattering at high spectral resolution, thus making up for the shortcomings of existing atmospheric radiative transfer models.

[0063] (2) The high-resolution atmospheric radiative transfer calculation method for greenhouse gases provided by this invention can be used to simulate the atmospheric top radiance (given spectral band or continuous spectrum) under different surface conditions, different observation geometry, and different atmospheric conditions under solar light source, and is applicable to a variety of scenarios.

[0064] (3) Compared with existing atmospheric radiation transfer models, the method of this invention has advantages such as high accuracy and high resolution, and is applicable to multiple scenarios, thus laying the foundation for satellite payload forward modeling and inverse modeling algorithm development. Attached Figure Description

[0065] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0066] Figure 1 This is a flowchart illustrating the method for calculating high-resolution atmospheric radiative transfer of greenhouse gases provided in an embodiment of the present invention.

[0067] Figure 2 This is a schematic diagram of the process for simultaneously simulating molecular absorption and particulate scattering provided in an embodiment of the present invention;

[0068] Figure 3 This is the result of the atmospheric top radiance calculation in the shortwave infrared band provided by an embodiment of the present invention. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0070] The inventive concept of this invention is as follows: In view of the problem that existing atmospheric radiative transfer models cannot simultaneously simulate molecular absorption and particulate scattering at high spectral resolution, the embodiments of this invention provide a high-resolution atmospheric radiative transfer calculation method for greenhouse gases. By calculating and modeling molecular absorption, particulate scattering, and surface reflection at high spectral resolution, the radiance of the top of the atmosphere is simulated, achieving high accuracy and high resolution calculation.

[0071] Figure 1 This is a flowchart illustrating the high-resolution atmospheric radiative transfer calculation method for greenhouse gases provided in an embodiment of the present invention. Figure 1 As shown in the example, this embodiment provides a method for calculating high-resolution atmospheric radiative transfer of greenhouse gases, including the following steps:

[0072] S1, obtain atmospheric state parameters.

[0073] The ECMWF ERA5 dataset, a meteorological reanalysis dataset, is used to obtain basic atmospheric state parameters, including atmospheric temperature, humidity, pressure profiles, and atmospheric molecular concentration profiles. The dataset encompasses long-term historical weather data with rich atmospheric elements and uniform spatiotemporal resolution, obtained by reconstructing past atmospheric states using ground-based, airborne, and spaceborne meteorological observation data, numerical models, and data assimilation techniques.

[0074] Another important atmospheric state parameter is the distribution of clouds and aerosols. The distribution information of cloud-aerosol parameter profiles in the atmosphere was obtained using measurements from the CALIPSO satellite, with a horizontal spatial resolution of 5 km. This information includes the types of clouds and aerosols, extinction coefficient profiles, and layered optical thickness. In real-world atmospheric environments, clouds and aerosols often coexist; therefore, radiative transfer calculations must consider the extinction of both clouds and aerosols.

[0075] S2 calculates the Doppler broadening caused by the Doppler frequency shift generated by molecular motion in the atmosphere, and calculates the collision broadening caused by the collisions between molecules, atoms and ions in the atmosphere.

[0076] The absorption lines of atmospheric molecules are not truly monochromatic; they actually possess a certain linewidth. Therefore, it is necessary to determine the extent of broadening. Collision broadening is proportional to atmospheric pressure and thus mainly occurs at low altitudes. Conversely, at high altitudes, Doppler broadening predominates. The process for analyzing absorption simulations is as follows: Figure 2 As shown.

[0077] S2.1, Considering the spectral broadening caused by the Doppler effect due to molecular motion, i.e., Doppler broadening, whose line shape function is Gaussian, the formula for calculating the half-width and half-maximum of the Doppler-broadened spectral line at a specific temperature T is:

[0078]

[0079] Where, α D (T) represents the full width at half maximum (FWHM) of the Doppler broadened spectral line, v ij The wavenumber represents the spectral line transition in vacuum, where i represents the isotope number of the gas molecule and j represents the discrete characteristic spectral wavenumber of the gas molecule, with units of cm. -1 c represents the speed of light in a vacuum, M represents the mass of a single molecule, and N represents the mass of a single molecule. A This represents Avogadro's constant as 6.02214129 × 10⁻⁶. 23 mol -1 k represents the Boltzmann constant, 1.380649 × 10⁻⁶. -16 erg·K -1 .

[0080] The Gaussian line shape function for Doppler broadening is:

[0081]

[0082] Among them, f G (v,v ij ,p,T) represents Doppler broadening, and v represents the wavenumber at any position.

[0083] S2.2, considering the irregular phase abrupt changes in the radiation wave train caused by collisions between molecules, atoms, and ions in the atmosphere, i.e., collision broadening, whose line shape function is Lorentz-type, the formula for calculating the half-maximum and half-width of the collision broadened spectral line under specific temperature T and pressure p is:

[0084]

[0085] Where γ(p,T) represents the full width at half maximum (FWHM) of the collision broadening spectral line, and T ref The reference temperature is 296K, n air γ represents the temperature coefficient of the air broadening half-width function. air The half-width and half-height of the air at standard atmospheric conditions (temperature 296 K, pressure 1 standard atmosphere) is represented by γ. self p represents the self-expanding half-height and half-width. self p represents the partial pressure of gas molecules in the atmosphere. ref This indicates the reference standard atmospheric pressure (1 atm).

[0086] The Lorentz line shape function for collision widening is:

[0087]

[0088] Among them, f D (v,v ij,p,T) represents collision widening, δ(p ref () indicates the frequency offset under the reference standard atmospheric pressure.

[0089] S3 calculates the combined broadening of atmospheric molecular spectral lines under the combined effects of Doppler broadening and collisional broadening. Based on the combined broadening, it calculates the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption.

[0090] In the actual atmosphere, the broadening of greenhouse gas absorption lines is often due to the combined effect of Doppler broadening and collisional broadening. In the examples, Voigt convolution is used to describe the combined broadening of molecular spectral lines by both factors.

[0091] S3.1, the overall broadening of atmospheric molecular spectral lines is represented by the Voigt convolution of Gaussian and Lorentz line types, calculated using the following formula:

[0092]

[0093] Where, f(v,v) ij (p,T) represents the overall broadening of atmospheric molecular spectral lines, f G (v,v ij ,p,T) represents Doppler broadening, f D (v,v ij (p,T) indicates collision widening. This indicates the Voigt convolution operation.

[0094] S3.2 After obtaining the overall broadened absorption line shape of atmospheric molecules, the absorption coefficient of atmospheric molecules can be obtained by combining the spectral line intensities from the high-resolution atmospheric molecular absorption spectral database (HITRAN2020). The calculation formula is as follows:

[0095] k ij (v,p,T)=S ij (T)f(v,v ij ,p,T)

[0096] Where, k ij (v,p,T) represents the absorption coefficient of atmospheric molecules, f(v,v) ij (p,T) represents the overall broadening, S ij (T) represents the spectral line intensity of the high-resolution atmospheric molecular absorption spectral database.

[0097] S3.3, the absorption coefficient, characterizes the absorption capacity of a single atmospheric molecule for solar radiation. Combined with the air molecule number density, it gives the total optical thickness of atmospheric molecules along the solar transmission path. The formula for calculating the total optical thickness of atmospheric molecules is:

[0098]

[0099] Where, τ ij (v,r) represents the total optical thickness of atmospheric molecules at wavenumber v and altitude r, X gas (r) represents the atmospheric molecular number density at the specified location, k ij (v,r) represents the atmospheric molecular absorption coefficient, the value of which is affected by wavenumber v and altitude r, where r grad and r TOA These represent the height of the Earth's surface and the top of the atmosphere, respectively.

[0100] S3.4, Optical thickness, as a dimensionless unit, is a key parameter describing the intensity of absorption of solar radiation by specific atmospheric molecules. Based on Beer-Lambert's law, the attenuation of light intensity after passing through a specific material due to absorption is:

[0101] I(v)=I0exp(-τ)

[0102] Where I(v) represents the light intensity attenuation at wavenumber v, I0 represents the incident light intensity of sunlight, and τ represents the optical thickness of the molecule, which can be calculated by the formula.

[0103] S4, calculate the optical properties of the particulate matter, including the scattering coefficient and extinction coefficient, based on the Mie scattering theory.

[0104] Atmospheric particulate scattering refers to the phenomenon where various solid and liquid particles in the atmosphere interact with light and alter its propagation state. The simulation process for particulate scattering is as follows: Figure 2 As shown.

[0105] According to Mie scattering theory, the interaction between particles and sunlight can be described using optical property parameters of the particles (such as scattering coefficient and extinction coefficient). First, the Mie scattering coefficient α is calculated. n and b n :

[0106]

[0107] Where x represents the scale parameter, r represents the particle radius, m represents the complex refractive index of the particle, the superscript ' indicates differentiation, and ψ n (x) and ξ n (x) represents the Riccati-Bessel function, which is calculated iteratively using the following formula:

[0108]

[0109] ξ n (x)=ψ n (x)-iχ n (x)

[0110] Where n represents the number of iterations.

[0111] In actual calculations, there are problems such as slow iterative convergence and excessive computation time. Therefore, the logarithmic derivative D is used. n (x) Calculate the Mie scattering coefficient:

[0112]

[0113] D n The recurrence relation for (x) is:

[0114]

[0115] Based on this, the extinction efficiency factor and backscattering efficiency factor of a single particle can be calculated:

[0116]

[0117] Among them, Q ext Q represents the extinction efficiency factor of a single particulate matter particle. back This represents the backscattering efficiency factor of a single particulate matter particle.

[0118] Substituting the calculated extinction and scattering efficiency factors into the following formula yields the extinction coefficient and scattering coefficient of the particulate matter:

[0119]

[0120] Where α represents the extinction coefficient, β represents the scattering coefficient, N0 represents the aerosol particle number density, and r m The median radius of the aerosol number concentration spectral distribution is represented by σ, where σ represents r. m The standard deviation, r represents the particle radius, r max r represents the maximum radius of the particulate matter. min This represents the minimum radius of the particulate matter.

[0121] The optical properties of the particulate scene can then be obtained by substituting the calculated extinction coefficient and scattering coefficient of a single particle into the particle cluster.

[0122] S5, combining land reflectance and ocean reflectance to obtain global surface reflectance.

[0123] S5.1, obtain land reflectance using the MODIS MCD43C4 dataset. This dataset provides 0.05... oIt also features two spatial resolutions: 500m and 16-day temporal resolution. MCD43C4 covers all seven bands of MODIS; therefore, in this embodiment, MODIS MCD43C4 data products are directly used as the surface reflectance input for the radiative transfer model. However, it should be noted that MODIS satellite surface reflectance data products only include the land portion; for the water portion, surface reflectance needs to be simulated based on Fresnel's law of reflection combined with an ocean reflectance model.

[0124] S5.2, ocean reflection is mainly composed of Fresnel reflection (reflection at the air-water interface), and secondarily, there is scattering contribution from ocean whitecaps (including ocean foam and sea bubbles). Therefore, the reflectivity of the ocean surface is calculated as follows, using the following formula:

[0125] R sea =(1-W)R s +WR f

[0126] Among them, R sea R represents ocean reflectivity. s R represents the Fresnel reflectance of the sea surface. f denoted by , where W represents the reflectance of the ocean white cap, and W represents the coverage of the ocean white cap.

[0127] Fresnel reflection from the ocean surface can be calculated using the following formula:

[0128]

[0129] Where ρ represents the Fresnel reflection coefficient, Ω represents the solid angle of the backscattering mode, and Ω L Ω represents the solid angle of the Lambertian scattering mode. In the zenith mode, Ω L =π. Therefore, the ocean backscattering solid angle can be written as Ω = 4π < S 2 >, in the formula <S 2 > represents the variance of ocean wave slope, which characterizes the roughness of the ocean surface. Ocean surface roughness is primarily constrained by ocean surface wind speed. The relationship between sea surface roughness and wind speed in the sea surface reflection model can be calculated using the following formula:

[0130] <S 2 >= 0.003 + 5.12 × 10 -3 U 12.4

[0131] Among them, U 12.4 This represents the wind speed at 12.4m above the sea surface. Alternatively, it can be based on the wind speed U at 10m above the sea surface. 10 The roughness of the ocean surface is quantified using the following formula.

[0132]

[0133] Wind speed is a major factor affecting wave slope and age, and its direction and amplitude determine the magnitude of sea surface reflectivity. Generally speaking, the higher the wind speed at the sea surface, the higher the roughness of the sea surface and the lower the sea surface reflectivity; however, excessively high wind speeds can also cause waves to break up, which in turn increases ocean whitecap scattering and thus enhances sea surface reflectivity.

[0134] In the zenith observation mode, the ocean white cap coverage is set to 0.02 and the ocean white cap reflectance is set to 0.08 in this embodiment. Global sea surface reflectance is calculated using U10 data from ECMWF ERA5 as simulation input, and the global surface reflectance in the zenith observation mode is obtained by combining this with MODIS land surface reflectance data.

[0135] S6 simulates the absorption of atmospheric molecules during radiative transfer and the attenuation of clouds and aerosols during radiative transfer, and combines this with global surface reflectance simulation to obtain the radiance of the top of the atmosphere.

[0136] The core of atmospheric radiative transfer models lies in solving the radiative transfer equation, which describes the process of radiation emitted by sunlight or lasers being transferred through the atmosphere. There are various methods for solving the radiative transfer equation. In this embodiment, the line-by-line integral radiative transfer model LBLRTM is used to simulate the absorption of sunlight by atmospheric molecules, and the discrete ordinate radiative transfer model DISORT is used to simulate the attenuation effect of clouds and aerosols on sunlight. The atmospheric molecular absorption spectrum database used is HITRAN 2020.

[0137] LBLRTM is a high-spectral-resolution atmospheric radiative transfer model based on the line-by-line integration method, capable of calculating atmospheric radiative and transmittance. This model relies on a high-spectral-resolution absorption spectral database as input; therefore, HITRAN 2020 was used in this embodiment to simulate the absorption spectral characteristics of atmospheric molecules. However, LBLRTM can only calculate molecular absorption and cannot simulate particulate scattering. Therefore, the DISORT model is used to compensate for this deficiency. The DISORT radiative transfer model is a computational model for simulating atmospheric and surface radiative transfer. It is primarily used to study the optical properties and transport processes of atmospheric components, as well as to simulate and predict the radiation field and spectral characteristics of the Earth's surface. The main features of the DISORT model include accurate modeling of the multispectral radiative characteristics of atmospheric components, the ability to simulate radiation field distribution under different spectral ranges and detection angles, and high accuracy and flexibility. By coupling the two radiative transfer models, the absorption and scattering of molecules and particles during radiative transfer can be accurately simulated. Combined with global surface reflectance simulation, the atmospheric top radiance is obtained. The calculated atmospheric top radiance in the shortwave infrared band is shown below. Figure 3 As shown.

[0138] The specific embodiments described above illustrate the technical solution and beneficial effects of the present invention in detail. It should be understood that the above description is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating high-resolution atmospheric radiative transfer of greenhouse gases, characterized in that, Includes the following steps: Acquire atmospheric state parameters, including: acquire atmospheric state parameters from the ECMWF ERA5 dataset of meteorological reanalysis data, and acquire cloud-aerosol distribution information measured by the CALIPSO satellite, including cloud and aerosol types, extinction coefficient profiles, and layered optical thickness; Calculate the Doppler broadening caused by the Doppler frequency shift generated by molecular motion in the atmosphere and the collision broadening caused by the collisions between molecules, atoms and ions. Calculate the comprehensive broadening of atmospheric molecular spectral lines under the combined effect of the two. Based on the comprehensive broadening, calculate the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption. The scattering coefficient and extinction coefficient of particulate matter were calculated based on Mie scattering theory. Global surface reflectance is obtained by combining land and ocean reflectance, including: land reflectance obtained from the MODIS MCD43C4 dataset, and ocean reflectance measured based on Fresnel reflection and the scattering contribution of the ocean whitecap. : ， in, This represents the Fresnel reflectance of the sea surface. Indicates the reflectance of the ocean white cap. Indicates the coverage rate of the ocean white cap; calculates... Introducing sea surface wind speed sea ​​surface roughness Constraints: ， in, This indicates the wind speed at a location 12.4 m above the sea surface; or based on the wind speed at a location 10 m above the sea surface. Quantifying the roughness of the ocean surface: ； The absorption of atmospheric molecules during radiative transfer and the attenuation of clouds and aerosols during radiative transfer are simulated, and the radiance of the top of the atmosphere is obtained by combining the simulation of global surface reflectance.

2. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 1, characterized in that, The calculation of Doppler broadening caused by the Doppler frequency shift resulting from molecular motion in the atmosphere includes: Consider the spectral broadening caused by the Doppler effect due to molecular motion, i.e., Doppler broadening, whose line shape function is Gaussian, at a specific temperature. The formula for calculating the full width at half maximum (FWHM) and full width at half maximum (FWHM) of the lower Doppler broadened spectral line is: ， in, This indicates the half-width and half-height of the Doppler broadened spectral line. The wavenumber represents the spectral line transition in vacuum. The isotope number representing a gas molecule. The wavenumber represents the discrete characteristic spectrum of gas molecules. This represents the speed of light in a vacuum. Indicates the mass of a single molecule. Represents Avogadro's constant. Represents the Boltzmann constant; The Gaussian line shape function for Doppler broadening is: ， in, This indicates Doppler widening. This represents the wave number at any given location.

3. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 2, characterized in that, The calculation of collision broadening caused by collisions between molecules, atoms, and ions includes: Consider the irregular phase abrupt changes in the radiation train caused by collisions between molecules, atoms, and ions in the atmosphere, i.e., collision broadening. Its linear function is Lorentz-type, and at a specific temperature... and pressure The formula for calculating the half-width and half-height of the lower collision broadened spectral line is: ， in, This indicates the half-width and half-height of the collision-broadened spectral line. Indicates reference temperature. The temperature coefficient representing the air half-width function. This represents the half-height and half-width of the air width under standard atmospheric conditions. This indicates a self-expanding half-height and half-width. Indicates the partial pressure of gas molecules in the atmosphere. Indicates the reference standard atmosphere; The Lorentz line shape function for collision widening is: ， in, Indicates collision widening. This indicates the frequency shift at the reference standard atmospheric pressure.

4. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 3, characterized in that, The comprehensive broadening of atmospheric molecular spectral lines under the combined effects of Doppler broadening and collisional broadening includes: The formula for calculating the overall broadening of atmospheric molecular spectral lines is: ， in, This indicates an overall broadening of atmospheric molecular spectral lines. This indicates Doppler widening. Indicates collision widening. This indicates the Voigt convolution operation.

5. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 4, characterized in that, The calculation of the absorption coefficient of atmospheric molecules, the total optical thickness of atmospheric molecules, and the light intensity attenuation caused by absorption, based on comprehensive broadening, includes: The formula for calculating the absorption coefficient of atmospheric molecules is: ， in, This represents the absorption coefficient of atmospheric molecules. Indicates overall widening. Indicates the spectral line intensity of the high-resolution atmospheric molecular absorption spectral database; The formula for calculating the total optical thickness of atmospheric molecules is: ， in, Indicates the wave number ,high Total optical thickness of atmospheric molecules at that location. This represents the atmospheric molecule number density at a specified location. This represents the atmospheric molecular absorption coefficient, and its value is affected by wavenumber. v ,high r Influence, as well as These represent the height of the Earth's surface and the top of the atmosphere, respectively. The formula for calculating the light intensity attenuation caused by absorption is: ， in, Indicates the wave number v Light intensity attenuation at that location This indicates the intensity of the incident sunlight. It represents the optical thickness of a molecule.

6. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 1, characterized in that, The optical characteristic parameters of the particulate matter, including the scattering coefficient and extinction coefficient, calculated based on Mie scattering theory, include: According to Mie scattering theory, the scattering coefficient and extinction coefficient of particulate matter are calculated to describe the interaction between particulate matter and sunlight. The calculation formula is as follows: ， in, Indicates the extinction coefficient. Represents the scattering coefficient. This represents the aerosol particle number density. The median radius represents the aerosol number concentration spectral distribution. express standard deviation The extinction efficiency factor represents the extinction efficiency of a single particulate matter particle. The backscattering efficiency factor represents the efficiency of a single particulate matter particle. Indicates the radius of the particulate matter. This indicates the maximum radius of the particulate matter. This represents the minimum radius of the particulate matter.

7. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 1, characterized in that, The simulation of the absorption of atmospheric molecules during radiative transfer and the attenuation of clouds and aerosols during radiative transfer includes: The LBLRTM radiative transfer model with line-by-line integration was used to simulate the absorption of atmospheric molecules during radiative transfer, while the DISORT radiative transfer model with discrete ordinates was used to simulate the attenuation of clouds and aerosols during radiative transfer.

8. The method for calculating high-resolution atmospheric radiative transfer of greenhouse gases according to claim 7, characterized in that, The atmospheric top radiance obtained by combining global surface reflectance simulation includes: By coupling the radiative transfer model LBLRTM and the radiative transfer model DISORT, the absorption and scattering of molecules and particles during radiative transfer are accurately simulated, and the radiance of the top of the atmosphere is obtained by combining the simulation of global surface reflectance.

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