Method and device for determining microwave ocean surface full polarization double-scale lower boundary conditions

Abstract

The application provides a microwave ocean surface full polarization double-scale lower boundary condition determination method and device, wherein the method comprises the following steps: obtaining microwave ocean surface full polarization double-scale lower boundary condition determination parameters; determining an ocean surface double-scale polarization BRDF matrix model according to the microwave ocean surface full polarization double-scale lower boundary condition determination parameters; and determining the microwave ocean surface full polarization double-scale lower boundary condition according to the ocean surface double-scale polarization BRDF matrix model. The ocean surface double-scale polarization BRDF matrix model in the method can have 16 complete matrix element analytical expressions and can generate Stokes reflection vector third and fourth components. Meanwhile, the ocean surface double-scale polarization BRDF matrix model in the method couples the influence of a wide range of ocean parameters on ocean surface emission and reflection, and can further improve the degree of sea-air coupling. Therefore, the method can effectively improve the simulation accuracy of the sea-air coupling radiation transfer model, optimize the ocean parameter inversion result, and further improve the ocean environment monitoring capability.

Description

Technical Field

[0001] This invention relates to the field of microwave air-sea coupled radiation transmission technology, and in particular to a method and apparatus for determining boundary conditions under microwave ocean surface full polarization dual-scale conditions. Background Technology

[0002] The total area of ​​the Earth's oceans is approximately 360 million square kilometers, accounting for about 71% of the Earth's surface. The oceans are not only closely linked to weather and climate change, but also have a significant impact on military and economic trade. Conducting marine environmental monitoring is of great importance for numerical simulation, ocean circulation, weather analysis, and climate change simulation. In the past, ocean monitoring mainly utilized buoys, submersibles, and seabed-based systems; however, these methods struggle to obtain large-scale, long-term, and timely observational data. Satellite platforms, due to their aforementioned advantages, have become an indispensable detection tool in the field of marine remote sensing. Microwaves, with their ability to penetrate clouds, rain, and particles, offer all-weather detection capabilities.

[0003] Ocean microwave remote sensing is a technique that utilizes the reflection and scattering characteristics of electromagnetic waves at the sea surface, as well as the microwave frequency characteristics naturally emitted by the sea surface, to obtain dynamic and thermal information about the sea surface. It also uses techniques such as polarization, phase analysis, and interferometry to obtain more comprehensive and accurate information about the ocean surface. The rapid development of spaceborne microwave remote sensing technology has led to an increasing number of satellites carrying dedicated passive or active microwave payloads for ocean remote sensing. Passive microwave instruments include microwave radiometers and microwave imagers. Active microwave instruments include microwave scatterometers, synthetic aperture radar, ocean altimeters, and ocean spectrometers. High-precision inversion of the physical parameters of the ocean surface by both active and passive payloads relies on high-precision radiative transfer models. This necessitates understanding the radiation characteristics of the ocean surface, conducting a clear and comprehensive study of the physical processes between electromagnetic waves and the ocean surface, and accurately simulating the radiative transfer processes of the ocean-atmosphere coupling system. Therefore, it is necessary to conduct in-depth and systematic research on the microwave radiative transfer mechanism at the sea-atmosphere interface.

[0004] First, in numerical weather prediction models, the ocean, atmosphere, and land are often treated separately, making the assimilation of radiation observations sensitive to multiple Earth systems suboptimal. This necessitates the development of advanced ocean-atmosphere coupled radiative transfer models to improve the application of passive microwave remote sensing observations in assimilation. Second, most current microwave polarized ocean-atmosphere coupled radiative transfer models can only simulate the vertical and horizontal components. However, the third and fourth components are crucial for inverting ocean surface wind fields and the thermal structure of the middle atmosphere. Furthermore, spaceborne passive microwave remote sensing lacks a physical ocean surface scattering model to provide a basis for calibration, uncertainty analysis, and parameter dependence analysis of various passive payloads. Solving these three problems requires the development of a fully polarized ocean surface electromagnetic scattering model. The sea surface is the bottom layer of the radiative transfer model, and as the lower boundary of the ocean-atmosphere coupled radiative transfer model, both emission and reflection need to be considered. In existing ocean-atmosphere coupled radiative transfer models, when considering the reflection contribution of the ocean surface, the ocean surface is either assumed to be a Lambertian reflector with a constant reflection coefficient over a wide wavelength range, or a geometrical optics model is used. The use of geometrical optics models in the microwave band is very limited. The contribution of the reflection term suffers from either using empirical models for simulation or overly simplistic physical descriptions, resulting in low air-sea coupling. There are three main emission models: the French LOCEAN model, which is entirely physical and only applicable to L-band emission calculations; the RSS empirical fitting model, obtained by fitting satellite observation data; and the parameterized fast model FASTEM, which is only applicable above 6 GHz and to small to medium observation zenith angles, and cannot calculate the third and fourth Stokes components. All of these reflection and emission models have certain application limitations. Regarding the lower boundary conditions of the models, CRTM, RTTOV, and ARMS currently calculate the emission vector using FASTEM first, and then subtract the FASTEM emission vector from the unit Stokes vector to obtain the reflection vector. This approach misses a significant amount of energy from ocean surface reflection. Kilic et al. used correction coefficients to handle the reflection contribution. Jin et al. used a dual-scale approach to describe reflection but employed a semi-empirical model for emission.

[0005] Currently, in terms of handling the lower boundary conditions, there is no existing technology that uses a unified theoretical physical model to simultaneously consider both emission and reflection in microwave air-sea coupled radiative transfer modes. This results in insufficient simulation capability and poor accuracy of existing radiative transfer modes for ocean surfaces. Summary of the Invention

[0006] This invention provides a method for determining boundary conditions under a fully polarized dual-scale microwave ocean surface, which effectively improves the simulation accuracy of air-sea coupled radiative transfer models, optimizes subsequent ocean parameter inversion results, and thus enhances the monitoring capabilities of the marine environment. The method for determining boundary conditions under a fully polarized dual-scale microwave ocean surface includes:

[0007] Obtain the determination parameters of the boundary conditions under fully polarized dual-scale conditions on the microwave ocean surface;

[0008] The BRDF matrix model for dual-scale polarization of the ocean surface is determined based on the parameters of the boundary conditions for the fully polarized dual-scale microwave ocean surface.

[0009] The boundary conditions for full polarization at two scales on the microwave ocean surface are determined based on the BRDF matrix model of the ocean surface at two scales.

[0010] In specific implementation, the parameters for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface include angular geometric parameters, wind vector parameters, frequency parameters, sea surface temperature parameters, and sea surface salinity parameters.

[0011] In specific implementation, determining the boundary conditions for the fully polarized dual-scale microwave ocean surface based on the ocean surface dual-scale polarization BRDF matrix model includes:

[0012] The ocean surface dual-scale polarization emissivity vector model is determined based on the ocean surface dual-scale polarization BRDF matrix model;

[0013] The boundary conditions for microwave ocean surface full polarization at two scales are determined based on the ocean surface dual-scale polarization BRDF matrix model and the ocean surface dual-scale polarization emissivity vector model.

[0014] In specific implementation, the method for determining the boundary conditions under the full polarization dual-scale of the microwave ocean surface also includes determining the full polarization air-sea coupled radiation transmission mode based on the boundary conditions under the full polarization dual-scale of the microwave ocean surface.

[0015] In specific implementation, determining the dual-scale polarization BRDF matrix model of the ocean surface based on the parameters of the boundary conditions under the full polarization dual-scale microwave ocean surface includes:

[0016] Obtain the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model, and sea spray model;

[0017] By substituting the parameters for determining the boundary conditions under the dual-scale full polarization of the microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface spectral model, truncated wavenumber model, dielectric constant model, and sea spray model, a dual-scale polarization BRDF matrix model of the ocean surface is obtained.

[0018] In specific implementation, the determination parameters of the boundary conditions under the fully polarized dual-scale microwave ocean surface are substituted into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model, and sea spray model to obtain the dual-scale polarized BRDF matrix model of the ocean surface, including:

[0019] Substituting the parameters for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, and dielectric constant modulus, the large-scale BRDF matrix and the small-scale BRDF matrix are determined.

[0020] Substitute the wind speed parameters into the sea spray model to obtain the sea spray reflectivity;

[0021] The ocean surface dual-scale polarization BRDF matrix model is determined based on the large-scale BRDF matrix, the small-scale BRDF matrix, and sea foam reflectivity.

[0022] In specific implementation, the ocean surface dual-scale polarization emissivity vector model is determined based on the ocean surface dual-scale polarization BRDF matrix model, and calculated according to the following formula:

[0023]

[0024]

[0025]

[0026] in, Represents the emissivity vector; A represents the ocean surface dual-scale polarization BRDF matrix; I i Represents the Stokes vector; A co Represents a large-scale BRDF matrix; A inco This represents a small-scale BRDF matrix; the subscript i represents incident radiation; the subscript s represents emitted radiation; δ represents the Dirac function. θ represents the azimuth angle; θ represents the zenith angle.

[0027] In specific implementation, the boundary conditions for microwave ocean surface full polarization at two scales are determined based on the ocean surface dual-scale polarization BRDF matrix model and the ocean surface dual-scale polarization emissivity vector model, and are calculated according to the following formula:

[0028]

[0029] Where I represents the Stokes vector; E represents the ocean surface dual-scale polarization emissivity vector model; A represents the ocean surface dual-scale polarization BRDF matrix model; S t denoted by Planck radiance; μ represents the cosine of the zenith angle; Indicates the azimuth angle.

[0030] The present invention also provides a radiance determination device, the radiance determination device comprising:

[0031] The parameter acquisition module is used to obtain the determination parameters of the boundary conditions under the fully polarized dual-scale microwave ocean surface.

[0032] The matrix model determination module is used to determine the dual-scale polarization BRDF matrix model of the ocean surface based on the determination parameters of the boundary conditions under the full polarization dual-scale microwave ocean surface.

[0033] The boundary condition output module is used to determine the boundary conditions under the full polarization dual-scale of the microwave ocean surface based on the ocean surface dual-scale polarization BRDF matrix model.

[0034] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for determining the boundary conditions under the full polarization dual-scale microwave ocean surface.

[0035] The present invention also provides a computer-readable storage medium storing a computer program for the method of determining boundary conditions under full polarization dual-scale microwave ocean surface.

[0036] The present invention provides a method and apparatus for determining the boundary conditions of a fully polarized dual-scale microwave ocean surface. The method includes: obtaining the determination parameters for the boundary conditions; determining a dual-scale polarized BRDF matrix model of the ocean surface based on the determination parameters; and determining the boundary conditions of the ocean surface based on the dual-scale polarized BRDF matrix model. Compared to traditional BRDF matrix models, the dual-scale polarized BRDF matrix model of this method can have 16 complete matrix elements for analytical expression, thereby improving the simulation accuracy of ocean surface microwave reflection. Furthermore, compared to traditional BRDF models and emissivity models, this model can generate the third and fourth components of the Stokes reflection vector, which is of great significance for detecting ocean surface wind fields, detecting the thermal structure of the middle atmosphere, and simulating radiative transfer in strongly scattering atmospheres. Simultaneously, the dual-scale polarized BRDF matrix model of this method couples the influence of a wide range of ocean parameters on ocean surface emission and reflection, further enhancing the air-sea coupling degree. Therefore, this method can effectively improve the simulation accuracy of the fully polarized air-sea coupled radiative transfer model, and subsequently optimize the ocean parameter inversion results, thereby enhancing the marine environmental monitoring capabilities. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some specific embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0038] Figure 1 This is a flowchart illustrating a method for determining boundary conditions under microwave ocean surface full polarization dual-scale according to a specific embodiment of the present invention.

[0039] Figure 2 This is a flowchart illustrating the process of determining the boundary conditions of microwave ocean surface fully polarized dual-scale based on the ocean surface dual-scale polarized BRDF matrix model according to a specific embodiment of the present invention.

[0040] Figure 3 This is a flowchart illustrating the process of determining the dual-scale polarization BRDF matrix model of the ocean surface based on the determination parameters of the boundary conditions under the full polarization dual-scale microwave ocean surface according to a specific embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram illustrating the specific process of constructing a dual-scale polarized BRDF matrix model of the ocean surface according to a specific embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the radiance determining device according to a specific embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram of the specific process for determining the boundary conditions under full polarization dual-scale microwave ocean surface according to a specific embodiment of the present invention;

[0044] Figure 7 This is a schematic diagram of the spatial distribution of the BRDF matrix under mirror geometry conditions according to a specific embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram illustrating the dependence of the emissivity vector on the azimuth angle according to a specific embodiment of the present invention;

[0046] Figure 9 This is a schematic diagram illustrating the differences between the 23.8 GHz ocean surface dual-scale polarization BRDF matrix model and the geometric optics BRDF matrix model according to a specific embodiment of the present invention;

[0047] Figure 10 This is a schematic diagram illustrating the difference in emitted radiation between the ocean surface dual-scale polarized emissivity vector model and FASTEM6 according to a specific embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the specific embodiments of the present invention clearer, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative specific embodiments and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0049] like Figure 1As shown, this invention provides a method for determining boundary conditions under a fully polarized dual-scale microwave ocean surface, which effectively improves the simulation accuracy of air-sea coupled radiative transfer models, optimizes subsequent ocean parameter inversion results, and thus enhances the monitoring capability of the marine environment. The method for determining boundary conditions under a fully polarized dual-scale microwave ocean surface includes:

[0050] 101: Obtain the determination parameters of the boundary conditions under the fully polarized dual-scale conditions of the microwave ocean surface;

[0051] 102: Determine the dual-scale polarization BRDF matrix model of the ocean surface based on the parameters for determining the boundary conditions under the full polarization dual-scale conditions of the microwave ocean surface;

[0052] 103: Determine the boundary conditions for full polarization at two scales on the microwave ocean surface based on the dual-scale polarization BRDF matrix model.

[0053] In specific implementation, the ocean surface refers to most of the ocean surface, excluding typhoon centers and areas with highly unstable stratification and sea ice coverage. The microwave refers to the microwave frequency band from 1 GHz to 200 GHz, which encompasses the detection range of most spaceborne passive payloads.

[0054] The dual-scale designation refers to the fact that, under wind speeds greater than 2 m / s and less than 30 m / s, ocean surface roughness relative to the incident electromagnetic wavelength can be divided into large-scale waves and small-scale waves, with the small-scale waves superimposed on the large-scale waves. A truncated wavenumber algorithm is used to calculate the truncated wavenumber to distinguish between large-scale and small-scale ocean surface roughness. To make the truncated wavenumber flexible, it is determined as a function of wind speed and frequency, rather than using a fixed truncated value. The BRDF contributions at large and small scales are calculated using different scattering theories.

[0055] The term "fully polarized" refers to the fact that, compared to the traditional 4×4 BRDF matrix which only yields 6 elements, the BRDF matrix derived based on the dual-scale theory can obtain values ​​for all 16 elements. This allows the reflected Stokes vector to acquire its third and fourth components. The emitted Stokes vector derived from the BRDF matrix also possesses third and fourth components. This makes the lower boundary condition a fully polarized Stokes vector for atmospheric radiation input.

[0056] In specific implementation, obtaining the ocean surface dual-scale polarized BRDF matrix model requires a seawater dielectric constant model, a sea surface roughness spectrum model, a truncated wavenumber model, a sea spray reflection model, a coverage area model, a Cox-Munk probability density function, a hydrodynamic modulation model, polarized BRDF micro-element theory, and a small perturbation method. The seawater dielectric constant model is used to provide the seawater dielectric constant. Furthermore, this application can use the Liu dielectric constant model, which is generated using observations of pure water and saline water in the 1.4-410 GHz frequency range, covering a sea surface temperature range of -2°C to 30°C. By using a dielectric constant model with a wide temperature and salinity range, the influence of sea surface temperature and salinity on ocean surface emission and emission can be coupled over a wide range. Compared to models that do not consider the influence of sea surface temperature and salinity, this effectively improves the degree of air-sea coupling. The sea surface roughness spectrum model is used to characterize the complete roughness spectrum of the ocean surface. This model can more realistically simulate sea surface conditions under windy conditions. The Duden-Vesecky spectral dual-scale scattering theory can well describe the dependence of scattering on frequency, polarization, incident angle, and wind speed within the 0-70° incident angle range. The truncated wavenumber model is used to distinguish between large-scale and small-scale ocean surfaces and is a function of frequency and wind speed. The sea spray reflection model and coverage area model are used to calculate sea spray reflectivity and sea spray coverage area. When the wind speed is greater than 7 m / s, sea spray begins to appear on the ocean surface. Sea spray reflectivity is mainly determined by the emissivity of the sea spray itself and the coverage area. Coverage area refers to the proportion of the field of view where sea spray appears. Furthermore, this application can use the Monahan sea spray coverage area model and the Stogryn sea spray reflectivity model. The Cox-Munk probability density function is used to describe the probability of observing a large-scale wave with a certain slope at a certain observation zenith angle. The hydrodynamic modulation model is used to simulate the interaction between large-scale and small-scale ocean surfaces. The polarized BRDF micro-element theory is used to calculate the BRDF of large-scale waves, while the small perturbation method is used to calculate the BRDF contribution of small-scale waves.

[0057] Furthermore, the parameters required for the seadrop reflection model and the coverage area model include wind speed, emission zenith angle, and frequency.

[0058] Furthermore, such as Figure 6As shown, the wind speed parameter refers to the wind speed at a height of 10m above the sea surface. Wind speed affects the sea surface spectrum; different wind speeds correspond to different sea surface spectrum shapes. The sea surface spectrum is used to describe the roughness of the sea surface. The cutoff wavenumber is also a function of wind speed and is used to distinguish between large-scale and small-scale waves. Changes in the wavenumber intervals encompassed by large and small scales will lead to changes in the amount of reflection contributed by each scale. The probability density distribution function is a function of wind speed and is used to describe the probability of a large-scale wave occurring at a certain slope. The magnitude of the wind speed determines the probability of a certain slope occurring. The hydrodynamic modulation model is also a function of wind speed; wind speed affects the hydrodynamic modulation process by influencing the slope of large-scale waves.

[0059] Furthermore, the frequency parameter, sea surface temperature parameter, and sea surface salinity parameter will affect the dielectric constant model. This is because the size scale is relative to the incident electromagnetic wave, therefore the cutoff wave number is also a function of frequency.

[0060] Furthermore, such as Figure 6 As shown, the geometric angle parameters include the zenith angle and azimuth angle at the incident point on the sea surface, and the zenith angle and azimuth angle at the outgoing point. These four angles, together with the large-scale waves on the sea surface, constitute the global coordinate system and the local coordinate system, respectively. The electromagnetic scattering calculation process is first performed in the local coordinate system and then rotated to the global coordinate system.

[0061] Furthermore, the reflection of sea droplets is determined by both the area covered by the sea droplets within the field of view and the reflection of the sea droplets themselves. Wind speed affects the area covered by the sea droplets, while the exit zenith angle and frequency determine the magnitude of the reflection of the sea droplets themselves.

[0062] In practice, there are multiple implementation schemes for selecting the parameters for determining the boundary conditions under the fully polarized dual-scale conditions of the microwave ocean surface. For example, the parameters for determining the boundary conditions under the fully polarized dual-scale conditions of the microwave ocean surface may include angular geometric parameters, wind speed parameters, frequency parameters, sea surface temperature parameters, and sea surface salinity parameters.

[0063] In practice, there are multiple implementation schemes for determining the microwave ocean surface fully polarized dual-scale lower boundary conditions based on the ocean surface dual-scale polarized BRDF matrix model. For example, the ocean surface dual-scale polarized emissivity vector model can be determined based on the ocean surface dual-scale polarized BRDF matrix model, and then the microwave ocean surface fully polarized dual-scale lower boundary conditions can be determined. The ocean surface dual-scale polarized emissivity vector model can be derived from the ocean surface dual-scale polarized BRDF matrix model based on Kirchhoff's theorem. Therefore, the emissivity model and the BRDF matrix model share the same physical mechanism. Furthermore, as... Figure 2 As shown, step 103: determining the boundary conditions for the fully polarized dual-scale microwave ocean surface based on the ocean surface dual-scale polarization BRDF matrix model, including:

[0064] 201: Determine the ocean surface dual-scale polarization emissivity vector model based on the ocean surface dual-scale polarization BRDF matrix model;

[0065] 202: Determine the boundary conditions for microwave ocean surface fully polarized dual-scale based on the ocean surface dual-scale polarized BRDF matrix model and the ocean surface dual-scale polarized emissivity vector model.

[0066] In specific implementation, after determining the lower boundary conditions of the fully polarized dual-scale microwave ocean surface, the fully polarized air-sea coupled radiation transfer mode can also be determined based on these lower boundary conditions. That is, the method for determining the lower boundary conditions of the fully polarized dual-scale microwave ocean surface can also include:

[0067] 104: Determine the fully polarized air-sea coupled radiation transfer mode based on the boundary conditions of the fully polarized dual-scale microwave ocean surface.

[0068] In practice, there are multiple implementation schemes for determining the surface dual-scale polarization BRDF matrix model, for example, Figure 3 As shown, step 102: determining the ocean surface dual-scale polarization BRDF matrix model based on the parameters of the boundary conditions under the microwave ocean surface fully polarized dual-scale conditions, includes:

[0069] 301: Obtain the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model, and sea spray model;

[0070] 302: Substitute the parameters of the boundary conditions under the full polarization dual-scale microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model and sea spray model to obtain the ocean surface dual-scale polarization BRDF matrix model.

[0071] In practice, there are multiple implementation methods for importing parameters into the model, for example, Figure 4 As shown, step 302 involves substituting the parameters of the boundary conditions under the fully polarized dual-scale microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface spectral model, truncated wavenumber model, dielectric constant model, and sea spray model to obtain the dual-scale polarized BRDF matrix model of the ocean surface, including:

[0072] 401: Substitute the parameters for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, and dielectric constant model to determine the large-scale BRDF matrix and the small-scale BRDF matrix;

[0073] 402: Substitute the wind speed parameters into the seadrop model to obtain the seadrop reflectivity;

[0074] 403: Determine the dual-scale polarization BRDF matrix model of the ocean surface based on the large-scale BRDF matrix, the small-scale BRDF matrix, and sea foam reflectivity.

[0075] Furthermore, the sea spray model includes a sea spray coverage area model and a sea spray reflection model.

[0076] In specific implementation, step 201 involves determining the ocean surface dual-scale polarization emissivity vector model based on the ocean surface dual-scale polarization BRDF matrix model, and calculating it according to the following formula:

[0077]

[0078]

[0079]

[0080] in, Represents the emissivity vector; A represents the ocean surface dual-scale polarization BRDF matrix; I i Represents the Stokes vector; A co Represents a large-scale BRDF matrix; A inco This represents a small-scale BRDF matrix; the subscript i represents incident radiation; the subscript s represents emitted radiation; δ represents the Dirac function. θ represents the azimuth angle; θ represents the zenith angle.

[0081] In specific implementation, step 202 involves determining the microwave ocean surface fully polarized dual-scale lower boundary conditions based on the ocean surface dual-scale polarized BRDF matrix model and the ocean surface dual-scale polarized emissivity vector model, and calculating them according to the following formula:

[0082]

[0083] Where I represents the Stokes vector; E represents the ocean surface dual-scale polarization emissivity vector model; A represents the ocean surface dual-scale polarization BRDF matrix model; S t denoted by Planck radiance; μ represents the cosine of the zenith angle; Indicates the azimuth angle.

[0084] Specifically, such as Figure 6As shown, determining the lower boundary conditions for the ocean-air coupled radiative transfer mode can include input parameters, a seawater dielectric constant model, a sea surface roughness spectrum model, a truncated wavenumber model, a sea spray reflection and coverage area model, a Cox-Munk probability density function, a hydrodynamic modulation model, polarized BRDF micro-element theory, and a small perturbation method. Furthermore, the core of this method is to derive a complete 16-element ocean surface dual-scale polarized BRDF matrix model based on dual-scale theory, and to obtain a homogeneous ocean surface dual-scale polarized emissivity vector model using Kirchhoff's laws. Both can serve as the boundary conditions for the complete microwave ocean-air coupled radiative transfer mode.

[0085] Furthermore, when constructing a two-scale polarized BRDF matrix model for the ocean surface, the electric field of a rough surface can typically be expressed as:

[0086]

[0087]

[0088] in, k is the wavenumber, r is the distance between the incident and scattered fields, the superscripts i and s represent the incident and scattered fields respectively, and v and h represent the vertical and horizontal polarizations respectively. The horizontal polarization lies on the reflection plane, and the vertical polarization is perpendicular to the reflection plane. The 2×2 amplitude scattering matrix S is related to the incident electric field E. i With the reflected electric field E s .

[0089] For scattered electromagnetic waves from the ocean surface, a 4×4 reflection coefficient matrix R is used to relate the scattered and incident Stokes vectors. The elements of the reflection matrix can be derived using the amplitude scattering matrix. Radiation from the ocean surface is often represented by the Stokes vector I = (I... v ,I h The scattered Stokes vector I is represented by (U,V). s With the incident Stokes vector I i It can be represented using a reflection coefficient matrix:

[0090]

[0091] Based on the relationship between the Stokes vector and the electric field vector, R can be represented by the elements of the amplitude scattering matrix S. Here, Re and Im represent the real and imaginary parts of the complex number, respectively.

[0092]

[0093] The two-scale theory divides ocean surface roughness into large and small scales relative to the incident electromagnetic wavelength, with the small scale superimposed on the large scale. Large-scale wavefronts can be simulated using the Geometric Optics (GO) model, while small-scale scattering can be simulated using the Small Perturbation Method (SPM). Large-scale wavefronts exhibit coherent scattering, contributed only by wavefronts within a unit field of view that satisfy Fresnel reflection for both incident and outgoing rays. Small-scale roughness scattering includes first-order incoherent scattering (SPM1) and second-order coherent scattering (SPM2). SPM2, similar to large-scale coherent scattering, occurs only in the specular reflection direction. SPM1, however, is contributed by all wavefronts within the field of view because incoherent scattering radiates in all directions.

[0094] Furthermore, the coherent scattering contribution can be calculated first. Coherent scattering includes both large-scale and small-scale second-order scattering. Calculating the coherent reflection matrix requires first calculating the corresponding reflection coefficient matrix.

[0095]

[0096] Among them, S vv and S hh It is the Fresnel reflection coefficient. It is the second-order reflection coefficient of the small perturbation method.

[0097] The reflection coefficient matrix of incoherent scattering can be expressed as:

[0098]

[0099] in, It is the first-order reflection coefficient of the small perturbation method.

[0100] According to the coherent reflection coefficient matrix S SC Incoherent reflection coefficient matrix S SI The corresponding 4×4 reflection coefficient matrix R can be obtained. SC and R SI The corresponding BRDF matrix can be derived from the reflection coefficient matrix. We represent the inverse BRDF matrix A as the coherent BRDF matrix A. co Incoherent BRDF matrix A inco The sum of the two parts.

[0101]

[0102]

[0103]

[0104] in It is a local coordinate system geometry. It is geometry in the global coordinate system. P(S)x ,S y ) is the Cox-Munk probability density distribution function, S x and S y S' represents the slope of the slope in the upwind and windward directions, respectively. x and S' y Let S and β represent the slopes along the scattering azimuth direction and perpendicular to the scattering azimuth direction, respectively; S is the shadow function; β is the cosine of the angle between the average surface normal and the slope normal; k0 is the free-space electromagnetic wave number; and W... s The small-scale portion of the ocean roughness spectrum is characterized by h, which is a hydrodynamic parameter, i1, which is the rotation angle between the incident and scattering planes, and i2, which is the angle between the outgoing and scattering planes.

[0105] For Stokes vector (I) v ,I h The rotation matrix (U,V) is expressed as follows.

[0106]

[0107] The total reflection matrix A is A co and A inco The sum, each element can be represented as follows:

[0108]

[0109] For the contribution of seadrop reflection, only the contribution of A is considered. vvvv and A hhhh It has an effect. The reflection matrix of seadrops will be further studied in the future.

[0110] Furthermore, when constructing a two-scale polarized emissivity vector model of the ocean surface, it is first necessary to assume that the downward atmospheric current is unpolarized. An incident electromagnetic wave of unit intensity amplitude can be expressed as:

[0111]

[0112] Furthermore, based on Kirchhoff's theorem, the emissivity vector It can be derived from the following formula:

[0113]

[0114]

[0115] Furthermore, by combining the ocean surface dual-scale polarization BRDF matrix model and the ocean surface dual-scale polarization emissivity vector model, the boundary conditions for the microwave ocean surface fully polarized dual-scale can be obtained:

[0116]

[0117] In specific implementation, such as Figure 7 As shown, the BRDF matrix represents the hemispherical spatial distribution of reflection under specular geometry conditions. The parameters are: frequency 19 GHz, wind speed 10 m / s, sea surface salinity 35‰, and sea surface temperature 285 K. It is important to emphasize that the BRDF matrix links incident irradiance and scattered irradiance from a small solid angle; therefore, the unit of each matrix element is 1 / sr. The values ​​of BRDF matrix elements do not need to be less than 1, but must be less than 1 after integration over the entire upper hemisphere. The reflectivity distribution of each element in the hemisphere is symmetric about the wind direction. The upwind and downwind directions are represented by 0° and 180°, respectively. Based on this symmetry, the BRDF matrix can be divided into four 2×2 submatrices. The submatrices in the upper left and lower right corners are even-symmetric with respect to the wind direction, while the submatrices in the upper right and lower left corners are odd-symmetric.

[0118] Figure 8 This section describes the dependence of the emissivity vector relative to the azimuth angle, derived from the BRDF matrix, under different wind speeds and with an observed zenith angle of 30°. In the emissivity... Figure 8 (a) shows the vertical and Figure 8 (b) shows that the azimuth variation of the horizontal polarization component increases with increasing wind speed and is symmetrical about wind direction. The upwind emissivity of the vertical polarization component is greater than that of the downwind component, while the opposite is true for the horizontal polarization component. Figure 8 The third Stokes component shown in (c) and Figure 8 (d) shows that the azimuth variation of the fourth Stokes component is oddly symmetric about the wind direction, and the oscillation amplitude increases with increasing wind speed.

[0119] Figure 9 This illustrates the difference between the 23.8 GHz ocean surface dual-scale polarized BRDF matrix model and the geometrical optical BRDF matrix model. The blue line represents the reflection contribution of the geometrical optical BRDF; it can be seen that the geometrical optical BRDF cannot generate the third and fourth components. SPM1 represents the first-order scattering contribution of small-scale waves, and SPM2 represents the second-order scattering contribution of small-scale waves. The sum of the contributions of SPM1 and SPM2 represents the difference between the dual-scale BRDF and the geometrical optical BRDF. It can be seen that SPM2 reduces the vertical and horizontal reflection contributions, while SPM1 increases them. Furthermore, the dual-scale model can contribute the third and fourth components.

[0120] Figure 10This section presents the difference in emitted radiation between the ocean surface dual-scale polarized emissivity vector model and FASTEM6. Since FASTEM6 lacks third and fourth components, only the vertical and horizontal components are compared here. In the vertical component, the largest deviation occurs at large angles for each frequency. Furthermore, this model exhibits the Brewster angle effect at large angles, while FASTEM does not. The higher the frequency, the smaller the Brewster angle. The deviation decreases when the observed zenith angle is greater than the Brewster angle. Overall, the deviation in the horizontal component is greater than that in the vertical component. The larger the zenith angle and the higher the frequency, the greater the deviation.

[0121] like Figure 5 As shown, the present invention also provides a radiance determination device, the radiance determination device comprising:

[0122] The parameter acquisition module 501 is used to acquire the determination parameters of the boundary conditions under the fully polarized dual-scale microwave ocean surface.

[0123] The matrix model is determined by modulo 502, which is used to determine the dual-scale polarization BRDF matrix model of the ocean surface based on the determination parameters of the boundary conditions under the full polarization dual-scale conditions of the microwave ocean surface.

[0124] Boundary condition output module 503 is used to determine the boundary conditions under microwave ocean surface full polarization at two scales based on the ocean surface dual-scale polarization BRDF matrix model.

[0125] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a method for determining the boundary conditions under the full polarization dual-scale microwave ocean surface.

[0126] The present invention also provides a computer-readable storage medium storing a computer program for the method of determining boundary conditions under full polarization dual-scale microwave ocean surface.

[0127] In summary, the present invention provides a method and apparatus for determining the boundary conditions of a fully polarized dual-scale microwave ocean surface. The method includes: obtaining the determination parameters for the boundary conditions; determining a dual-scale polarized BRDF matrix model of the ocean surface based on the determination parameters; and determining the boundary conditions of the ocean surface based on the dual-scale polarized BRDF matrix model. Compared to traditional BRDF matrix models, the dual-scale polarized BRDF matrix model of the ocean surface in this method can have 16 complete analytical matrix elements, thereby improving the simulation accuracy of ocean surface microwave reflection. Furthermore, compared to traditional BRDF models and emissivity models, this model can generate the third and fourth components of the Stokes reflection vector, which is of great significance for detecting ocean surface wind fields, detecting the thermal structure of the middle atmosphere, and simulating radiative transfer in strongly scattering atmospheres. Simultaneously, the dual-scale polarized BRDF matrix model of the ocean surface in this method couples the influence of a wide range of ocean parameters on ocean surface emission and reflection, further enhancing the air-sea coupling degree. Therefore, this method can effectively improve the simulation accuracy of the fully polarized air-sea coupled radiative transfer model, and subsequently optimize the ocean parameter inversion results, thereby enhancing the marine environmental monitoring capabilities.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for determining boundary conditions under fully polarized dual-scale conditions on microwave ocean surfaces, characterized in that, The method for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface includes: Obtain the determination parameters of the boundary conditions under fully polarized dual-scale conditions on the microwave ocean surface; The BRDF matrix model for dual-scale polarization of the ocean surface is determined based on the parameters of the boundary conditions for the fully polarized dual-scale microwave ocean surface. Based on the aforementioned ocean surface dual-scale polarization BRDF matrix model, the ocean surface dual-scale polarization emissivity vector model is determined using the following formula: ； ； ； in, Represents the emissivity vector; Represents the two-scale polarization BRDF matrix of the ocean surface; Represents the Stokes vector; Represents a large-scale BRDF matrix; Represents a small-scale BRDF matrix; subscript Indicates incident radiation; subscript Indicates emitted radiation; Represents the Dirac function; Indicates azimuth; Indicates the zenith angle; Based on the aforementioned dual-scale polarization BRDF matrix model and the aforementioned dual-scale polarization emissivity vector model for the ocean surface, the boundary conditions for the fully polarized dual-scale microwave ocean surface are determined, and the calculation formula is as follows: ； in, Represents the Stokes vector; Represents a two-scale polarized emissivity vector model of the ocean surface; Represents a dual-scale polarization BRDF matrix model of the ocean surface; Indicates the Planck radiance; The cosine of the zenith angle; Indicates the azimuth angle.

2. The method for determining boundary conditions under fully polarized dual-scale microwave ocean surface as described in claim 1, characterized in that, The parameters for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface include angular geometric parameters, wind vector parameters, frequency parameters, sea surface temperature parameters, and sea surface salinity parameters.

3. The method for determining boundary conditions under fully polarized dual-scale microwave ocean surface as described in claim 1, characterized in that, The method for determining the boundary conditions of the microwave ocean surface under full polarization at two scales also includes determining the fully polarized air-sea coupled radiation transmission mode based on the boundary conditions of the microwave ocean surface under full polarization at two scales.

4. The method for determining boundary conditions under fully polarized dual-scale microwave ocean surface as described in claim 2, characterized in that, The determination of the ocean surface dual-scale polarization BRDF matrix model based on the determination parameters of the boundary conditions under the full polarization dual-scale conditions of the microwave ocean surface includes: Obtain the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model, and sea spray model; By substituting the parameters for determining the boundary conditions under the dual-scale full polarization of the microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface spectral model, truncated wavenumber model, dielectric constant model, and sea spray model, a dual-scale polarization BRDF matrix model of the ocean surface is obtained.

5. The method for determining the boundary conditions under two-scale full polarization of microwave ocean surface as described in claim 4, wherein substituting the parameters for determining the boundary conditions under two-scale full polarization of microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, dielectric constant model, and sea spray model to obtain the ocean surface two-scale polarization BRDF matrix model includes: Substituting the parameters for determining the boundary conditions under the fully polarized dual-scale microwave ocean surface into the hydrodynamic modulation model, probability density distribution function, sea surface wave spectrum model, truncated wavenumber model, and dielectric constant model, the large-scale BRDF matrix and the small-scale BRDF matrix are determined. Substitute the wind speed parameters into the sea spray model to obtain the sea spray reflectivity; The ocean surface dual-scale polarization BRDF matrix model is determined based on the large-scale BRDF matrix, the small-scale BRDF matrix, and sea foam reflectivity.

6. A device for determining boundary conditions under two scales of full polarization on microwave ocean surface, characterized in that, The device for determining the boundary conditions of the fully polarized dual-scale microwave ocean surface includes: The parameter acquisition module is used to acquire the determination parameters of the boundary conditions under the fully polarized dual-scale microwave ocean surface. The matrix model determination module is used to determine the dual-scale polarization BRDF matrix model of the ocean surface based on the determination parameters of the boundary conditions under the full polarization dual-scale microwave ocean surface. The boundary condition output module is used to determine the ocean surface dual-scale polarization emissivity vector model based on the ocean surface dual-scale polarization BRDF matrix model. The calculation formula is as follows: ； ； ； in, Represents the emissivity vector; Represents the two-scale polarization BRDF matrix of the ocean surface; Represents the Stokes vector; Represents a large-scale BRDF matrix; Represents a small-scale BRDF matrix; subscript Indicates incident radiation; subscript Indicates emitted radiation; Represents the Dirac function; Indicates azimuth; Indicates the zenith angle; The boundary condition output module is also used to determine the boundary conditions under the full polarization dual-scale of the microwave ocean surface based on the ocean surface dual-scale polarization BRDF matrix model and the ocean surface dual-scale polarization emissivity vector model. The calculation formula is as follows: ； in, Represents the Stokes vector; Represents a two-scale polarized emissivity vector model of the ocean surface; Represents a dual-scale polarization BRDF matrix model of the ocean surface; Indicates the Planck radiance; The cosine of the zenith angle; Indicates the azimuth angle.

7. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method for determining the boundary conditions under fully polarized dual-scale microwave ocean surface as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that performs the method for determining boundary conditions under fully polarized dual-scale microwave ocean surfaces as described in any one of claims 1 to 5.

Images