Multi-scale sea surface electromagnetic scattering calculation method and device based on marine environment elements

Abstract

The invention discloses a multi-scale sea surface electromagnetic scattering calculation method and device based on marine environment elements and a storage medium, and belongs to the technical field of marine detection and physical remote sensing. The method comprises the following steps: calculating a tension wave sea spectrum according to an Elfouhail sea spectrum in combination with a Longuet-Higgins directional spectrum; a JONSWAP sea spectrum is combined with a Longuet-Higgins directional spectrum to calculate a gravity wave sea spectrum; superposing the tension wave on the gravity wave according to the slope by using a linear superposition method, and calculating a self-adaptive cut-off wave number; the contribution of small-scale waves to scattering is calculated by adopting an integral equation method, mirror scattering of large-scale waves is counted by adopting a Kirchhoff approximation method, and statistics and fusion are carried out on each scale wave according to the self-adaptive cut-off wave number, so that an electromagnetic scattering value is obtained. According to the method, a sea surface geometric calculation method based on real marine environment element driving is adopted, and accurate calculation is performed aiming at sea surface scattering characteristics under different sea conditions in combination with an integral equation method-Kirchhoff approximation electromagnetic scattering calculation model of an adaptive cut-off wave number, so that the calculation precision of scattering intensity is improved.

Description

Technical Field

[0001] This invention belongs to the field of marine exploration and physical remote sensing technology, and relates to electromagnetic wave scattering characteristic simulation and radar remote sensing signal processing. Specifically, it relates to a multi-scale sea surface electromagnetic scattering calculation method and equipment based on marine environmental factors. Background Technology

[0002] In recent years, with the rapid development of technologies such as marine remote sensing and radar detection, the demand for high-precision modeling and simulation of sea surface electromagnetic scattering behavior has been continuously increasing. In the process of modeling sea surface electromagnetic scattering, geometric modeling of the sea surface is a fundamental step, and its accuracy directly affects the reliability and practicality of subsequent electromagnetic scattering characteristic analysis. Currently, the mainstream method for sea surface geometric modeling is the sea spectrum method based on random wave theory. The sea spectrum, also known as the power spectrum of ocean waves, reflects the energy and frequency distribution of ocean waves and is a fundamental representation of sea surface fluctuations. Classical sea spectra include PM spectra and Elfouhaily spectra, with the Elfouhaily spectrum being widely used due to its good compatibility with the multi-scale characteristics of wind-driven waves. However, these wind-driven sea spectra mainly rely on wind speed as a parameter to determine the shape and characteristics of the spectrum, lacking the ability to directly represent and flexibly model real wave elements such as wave height, wavelength, and dominant direction, making it difficult to comprehensively and realistically reflect the complex sea surface conditions under the required environment. In reality, the interaction between electromagnetic waves and the sea surface mainly occurs at the level of the microscopic geometry of the sea surface. Its scattering characteristics are sensitive to local morphology of wave surfaces, especially complex multi-scale waves and breaking waves. Therefore, it is urgent to introduce a hybrid modeling framework with measured or statistical wave characteristic parameters as input conditions to supplement the shortcomings of traditional oceanographic methods.

[0003] Among wave spectrum-driven geometric modeling methods, linear superposition and linear filtering are common. Linear superposition, by representing any point on the sea surface as a linear superposition of countless random cosine components, can generate a wave surface with the statistical characteristics of the target spectrum. Linear filtering, on the other hand, uses Gaussian white noise as input and performs frequency domain convolution through a filter corresponding to the target spectrum, thereby efficiently simulating sea surface morphology with a specific spectral distribution. These methods provide a controllable and diverse foundation for subsequent electromagnetic scattering modeling of sea surface geometry.

[0004] The surface model obtained based on sea surface geometry modeling can be further analyzed for electromagnetic scattering characteristics. Classical two-scale methods generally suffer from problems such as the Kirchhoff Approximation (KA) and Small Perturbation Method (SPM) not being able to fully cover the entire range of sea surface roughness and gradient variations, and being highly sensitive to the selection of the cutoff wavenumber parameter. These issues affect the model's consistency and robustness under different sea states.

[0005] In summary, existing technologies for modeling sea surface geometry and electromagnetic scattering are limited by single-parameter driving, insufficient local characteristic modeling capabilities, limited coverage of dual-scale methods, and the influence of truncation parameter selection. These limitations make it difficult to meet the urgent needs of practical applications for multi-scale, measurement-driven, and robust scattering analysis models. To address these issues, a multi-scale modeling method that integrates real marine environmental elements and employs mechanisms such as adaptive truncation wavenumbers is urgently needed to achieve efficient and accurate analysis and simulation of electromagnetic scattering characteristics under complex sea surface conditions. Therefore, this paper proposes an integral equation method-Kirchhoff approximation (IEM-KA) based on adaptive truncation wavenumbers under geometric sea surface conditions modeled from real marine environmental elements. The effectiveness of the proposed method is verified through comparison with widely used empirical models and measured data. Summary of the Invention

[0006] To overcome the shortcomings of existing sea surface electromagnetic scattering modeling methods, such as the single sea spectrum driving method, insufficient ability to model real wave elements, and limited applicability and parameter sensitivity of electromagnetic scattering dual-scale analysis methods, this invention proposes a method that can integrate real marine environmental elements, take measured or statistical wave characteristic parameters as input, and achieve high-precision electromagnetic scattering characteristic modeling and simulation analysis of complex sea surfaces at multiple scales through a large- and small-scale modeling framework that integrates IEM (integral equation method) and KA (Kirchhoff approximation) with adaptive truncated wavenumbers.

[0007] This invention provides a method for calculating multi-scale sea surface electromagnetic scattering based on marine environmental factors, comprising:

[0008] Step 1: Calculate the tension wave spectrum based on the Elfouhaily sea spectrum combined with the Longuet-Higgins directional spectrum;

[0009] Step 2: Calculate the gravitational wave spectrum using the JONSWAP sea spectrum combined with the Longuet-Higgins directional spectrum;

[0010] Step 3: Use the linear superposition method to superimpose the tension wave onto the gravity wave according to the slope, and calculate the adaptive cutoff wave number;

[0011] Step 4: Calculate the contribution of small-scale waves to scattering using the integral equation method and statistically analyze the specular scattering of large-scale waves using the Kirchhoff approximation method. Statistically fuse the waves at each scale based on the adaptive truncation wavenumber to obtain the electromagnetic scattering value.

[0012] Furthermore, in steps 1 and 2, the Longuet-Higgins directional spectrum is expressed in one-sided cosine form as follows:

[0013]

[0014] Among them, c m To obtain the curvature spectrum gravity-capillary peak value k m The minimum phase velocity at time t; s is a parameter controlling propagation; Wave direction angle; c represents the wind direction; c represents the wave phase velocity; c p =c(k p () represents the phase velocity at the peak of the spectrum;

[0015] Further, in step 1, the Elfouhaily spectral expression is:

[0016] S E (k)=k -3 [B l (k)+B h (k)]

[0017] Among them, S E (k) represents the Elfouhaily sea surface spectrum; B l B h Let B = k be the low-frequency curvature spectrum corresponding to gravity waves and the high-frequency curvature spectrum corresponding to tension waves. 3 S, k is the incident wave number, S is the energy spectrum;

[0018] B h (k)=0.5α m c m F m / c

[0019]

[0020] F m =exp[-1.25(k / k p ) -2 ]exp[-0.25(k / k m -1) 2 ]

[0021] Among them, F m The shortwave action function; frictional wind speed u f The unit is m / s;

[0022] The tension wave spectrum S capillary for:

[0023]

[0024] Further, in step 2, the wave number spectrum of the JONSWAP sea spectrum is:

[0025]

[0026] Among them, H s Significant wave height; T p γ is the peak period; γ is the peak elevation factor; the dimensionless spectral width parameter σ1 is expressed as:

[0027]

[0028] Where f is the frequency domain; f p The frequency of the spectral peak;

[0029] The gravity wave spectrum S gravity for:

[0030]

[0031] Furthermore, in step 3, the step of superimposing Zhang Libo onto the gravity wave according to the slope is as follows:

[0032] z = η gravity (x,y,t)+η capillary (x,y,t)+Z x x+Z y y

[0033] Where z represents the height fluctuation of the superimposed waves; η gravity (x,y,t) represents the height variation of the center of the gravity wave surface element in the multi-scale marine environmental element; η capillary (x,y,t) represents the amplitude values ​​of tension waves, a multi-scale marine environmental element; (x,y) represents the positional coordinate vectors of microstructures within the tension wave surface element; Z x and Z y These are the slopes of the gravitational wave in the x and y directions, respectively.

[0034]

[0035]

[0036] Where, η gravity (x,y,t) and η capillary(x,y,t) is obtained by calculating η(x,y,t), where Select either tension wave spectroscopy or gravity wave spectroscopy; ω i Angular frequency; ∈ ij This is the initial random phase.

[0037] Furthermore, in step 3, the adaptive truncation wavenumber k c for:

[0038]

[0039] Wherein, S(K) is the wave height fluctuation z obtained by Fourier transform after superposition.

[0040] Furthermore, in step 4, the contribution of small-scale waves to scattering after adaptive truncation wavenumber partitioning is calculated using the integral equation method:

[0041]

[0042] Where, θ i σ is the angle of incidence; σ is the standard deviation of surface roughness; f PQ F PQ Represents the polarization factor f vv ,f hh The polarization factors F under VV and HH polarizations are respectively. vv ,F hh These are the polarization factors under VV and HH polarization, respectively.

[0043] Furthermore, in step 4, the Kirchhoff approximation method is used to calculate the contribution of large-scale waves to scattering after adaptive truncation wavenumber partitioning:

[0044]

[0045] Where, θ s It is the scattering angle; q is the phase factor; Z is the scattering angle. x =-q x / q z Z y =-q z ;U pQ P(Z) represents the polarization coefficient; x Z y ) is a slope probability density function on a large scale.

[0046] Furthermore, in step 4, the wave statistics at each scale are statistically fused based on the adaptive truncation wavenumber as follows:

[0047]

[0048] Wherein, <·> represents the ensemble average of the scattering contribution of small-scale waves based on the sea surface slope determined by large-scale waves.

[0049] The present invention also provides a computer device / equipment / system, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors described above.

[0050] The present invention also provides a computer-readable storage medium storing a computer program / instructions thereon, which, when executed by a processor, implements the steps of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors described above.

[0051] The present invention also provides a computer program product, including a computer program / instruction that, when executed by a processor, implements the steps of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors described above.

[0052] The beneficial effects of this invention are as follows:

[0053] The method of this invention introduces an adaptive cutoff wavenumber to enhance the applicability and accuracy of electromagnetic scattering modeling. At the same time, it solves the problem that the traditional electromagnetic scattering backscattering coefficient calculation does not fully consider marine environmental factors. This method can more realistically restore the detailed texture features of the sea surface and shows lower scattering error under different sea states, multiple frequency points, and different polarization conditions. It has high modeling accuracy and good adaptability and can effectively fit the actual scattering characteristics. Attached Figure Description

[0054] Figure 1 This is a flowchart of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors proposed in this invention.

[0055] Figure 2 Model the geometric sea surface for each sea state; Figure (a) shows the geometric sea surface for sea state 1; Figure (b) shows the geometric sea surface for sea state 2; Figure (c) shows the geometric sea surface for sea state 3; Figure (d) shows the geometric sea surface for sea state 4; Figure (e) shows the geometric sea surface for sea state 5; and Figure (f) shows the geometric sea surface for sea state 6.

[0056] Figure 3 The present invention compares the proposed method with the NRL model under different sea conditions; Figure (a) shows the electromagnetic scattering intensity of sea clutter with different polarizations at 10 GHz and the radar carrier frequency; Figure (b) shows the electromagnetic scattering intensity of sea clutter with different polarizations at 15 GHz and the radar carrier frequency.

[0057] Figure 4This paper compares the proposed method with the KaDPMod model under different sea states and ground smear angles. Figure (a) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 1; Figure (b) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 2; Figure (c) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 3; Figure (d) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 4; Figure (e) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 5; and Figure (f) shows the VV-polarized sea clutter electromagnetic scattering intensity versus radar ground smear angle under sea state 6.

[0058] Figure 5 The present invention compares the proposed method with measured data under different sea states and ground rubbing angles. Figure (a) shows the electromagnetic scattering intensity of sea clutter in sea state 1 with radar ground rubbing angle; Figure (b) shows the electromagnetic scattering intensity of sea clutter in sea state 2 with radar ground rubbing angle; Figure (c) shows the electromagnetic scattering intensity of sea clutter in sea state 3 with radar ground rubbing angle; and Figure (d) shows the electromagnetic scattering intensity of sea clutter in sea state 4 with radar ground rubbing angle. Detailed Implementation

[0059] The present invention will now be further described with reference to the accompanying drawings.

[0060] This invention proposes a multi-scale sea surface electromagnetic scattering modeling algorithm driven by real marine environmental factors. First, tension waves are generated based on the Elfouhaily sea spectrum. Then, gravity waves are modeled using an optimized JONSWAP sea spectrum based on real wave characteristic parameters such as significant wave height, dominant wave direction, spectral width, and wind speed. Next, the tension waves are superimposed onto the gravity waves using a linear superposition method according to their slopes. Finally, the IEM-KA method is used to calculate the electromagnetic scattering of the sea surface. Figure 1 As shown, it specifically includes:

[0061] (1) Tension waves were constructed based on the Elfouhaily sea spectrum;

[0062] The wavenumber energy spectrum of the Elfouhaily sea surface can be decomposed into two parts, defined as follows:

[0063] S E (k)=k -3 [B l (k)+B h (k)] (1)

[0064] Among them, B l (k) represents the long-wave curvature spectrum, B h (k) Shortwave curvature spectrum, B = k 3 S and B represent curvature spectrum, and S represents energy spectrum.

[0065] B h (k)=0.5α m c m F m / c (2)

[0066]

[0067] Among them, frictional wind speed u f The unit is m / s, c m It is the peak value of the curvature spectrum gravity-capillary wavelet. m The minimum phase velocity at time is generally taken as k. m =(ρ w g / T) 0.5 =370rad / m,c m =(2g / k m ) 0.5 =0.23m / s, F m The shortwave action function is denoted as F. m for

[0068] F m =exp[-1.25(k / k p ) -2 ]exp[-0.25(k / k m -1) 2 (4)

[0069] (2) Gravity waves were modeled using real marine environmental parameters and constructed using JONSWAP sea spectrum.

[0070] JONSWAP sea spectrum optimized by the Goda team in Japan

[0071]

[0072] In the formula, S J (f) Characterizing the frequency distribution of wave energy, H s For significant wave height, T p The peak period is γ, the peak elevation factor is γ, and the rest of the calculations follow the core framework of the classical JONSWAP model. The dimensionless spectral width parameter σ1 is expressed as follows:

[0073]

[0074] Among them, f p Represents the frequency of spectral peaks.

[0075] (3) The direction spectrum is selected using the single-sided cosine form used by Longuet-Higgins;

[0076]

[0077] Where s is a parameter controlling the propagation. Represents the wave direction angle. The wind direction.

[0078] (4) Calculate the tension wave spectrum and gravity wave spectrum

[0079]

[0080] (5) Using the linear superposition method, the tension wave is superimposed onto the gravity wave according to the slope.

[0081]

[0082] z = η gravity (x,y,t)+η capillary (x,y,t)+Z x x+Z y y (19)

[0083] Where, η gravity (x,y,t) and η capillary (x, y, t) can be calculated separately using formula (16), when calculating η gravity When (x,y,t), in formula (15) Take the index of the gravitational wave spectrum at (i, j); when calculating η capillary When (x,y,t), in formula (15) Take the index of the tensile wave spectrum at (i, j); A ij The amplitude of a tension wave or a gravity wave; Let η(x,y,t) represent the two-dimensional wave spectral density, and z represent the wave height fluctuation after superposition.

[0084] (6) Calculate the adaptive cutoff wavenumber k cut

[0085] The formula describing sea surface roughness is as follows:

[0086]

[0087] The sea surface roughness is

[0088]

[0089] Where κ represents the von Karman constant, U * This represents the frictional wind speed, and the frictional wind speed and the wind speed at 10m above the sea surface have the following relationship:

[0090]

[0091] definition

[0092]

[0093] From formulas (23) to (27), we can obtain the information regarding the cutoff wavenumber k. cut Functional relationship:

[0094]

[0095] Where, σ capillary_wave Let S(K) be the root mean square height of the small-scale wave on the sea surface, and S(K) be the Fourier transform of the generated geometric sea surface height undulation z. cut denoted as k, representing the cutoff wavenumbers for both large and small scale waves. Due to the viscous damping of the actual sea surface caused by seawater, the capillary wave component in the sea surface spectrum model contributes significantly to the root-mean-square slope and higher-order derivatives; therefore, the upper and lower limits of the space wavenumber must be truncated. c k is the upper limit of the space wavenumber. c ≥8k p And k p The adaptive cutoff wavenumber can be determined by formula (25) for the peak wavenumber.

[0096] (7) The contribution of small-scale waves to scattering after wavenumber division was calculated using the integral equation method (IEM).

[0097]

[0098] In the formula, k is the incident wave number, and θ i It is the angle of incidence, and σ is the standard deviation of the surface roughness.

[0099]

[0100] f vv =2R vv / cosθ(28)

[0101] f hh =-2R hh / cosθ(29)

[0102]

[0103] Among them, S (n) (q,0) is the nth-order sea surface spectral function, f PQ F PQ f represents the polarization factor. vv ,f hh These are the polarization factors under VV and HH polarizations, respectively, F vv ,F hh These are the polarization factors under VV and HH polarization, respectively.

[0104] (8) Use the Kirchhoff approximation (KA) method to statistically analyze the specular scattering of large-scale waves after division by truncation wavenumber.

[0105]

[0106] Where, θ i It is the angle of incidence, θ s It is the scattering angle. It is the azimuth angle, q is the phase factor, and Z is the azimuth angle. x =-q x / q z Z y =-q z U pQ P(Z) represents the polarization coefficient. x Z y () is the slope probability density function on a large scale after dividing based on the truncated wavenumber;

[0107] (9) Statistical fusion of the contributions of large-scale wave specular scattering and small-scale wave scattering to scattering

[0108]

[0109] Where P represents the polarization of the scattered field, and Q represents the polarization of the incident field. The symbol <·> represents the ensemble averaging of the scattering contribution of small-scale waves based on the sea surface slope determined by large-scale waves.

[0110] from Figure 2 It can be seen that the sea surface amplitude of tension waves generated based on the JONSWAP spectrum is significantly smaller than that of gravity waves. The sea surface amplitude after the tension waves are superimposed is the same as that of gravity waves, but the sea surface texture is clearer and the details are more complete than those of gravity waves. At the same time, the effect of gravity waves becomes more obvious as the sea state increases, which is consistent with the actual situation.

[0111] from Figure 3 It can be seen that the present invention exhibits lower errors under HH and VV polarization conditions at 10GHz and 15GHz frequencies, and significantly improves the accuracy of scattering modeling compared to the combination of JONSWAP sea spectrum and traditional dual-scale method.

[0112] from Figure 4 As can be seen, the present invention can fit the actual scattering characteristics well in all six sea state levels, and the overall trend is basically consistent with the KaDPMod model. The RMSE is within 5dB, which further verifies the wide adaptability and robustness of the proposed method under different sea state conditions.

[0113] from Figure 5It can be seen that the method proposed in this invention exhibits excellent fitting results under different sea states and different measured data conditions. Regardless of whether it is sea state 1, 2, 3 or 4, the curve of scattering intensity as a function of radar incident angle obtained by the method of this invention is highly consistent with the trend of measured values, and the overall error is significantly smaller than that of the traditional JONSWAP spectrum and the fourth-order approximate truncation dual-scale method.

[0114] In summary, to address the shortcomings of existing sea surface electromagnetic scattering modeling methods, such as insufficient representation of multi-scale wave morphology and real-world environmental elements, and limited scattering accuracy, this invention proposes a multi-scale sea surface electromagnetic scattering modeling algorithm based on marine environmental elements. Simulation results demonstrate that this method can more realistically reproduce the detailed texture features of the sea surface, exhibiting lower scattering errors under different sea states, multiple frequency points, and different polarization conditions. It possesses high modeling accuracy and good adaptability, effectively fitting actual scattering characteristics, thus verifying the accuracy and robustness of the proposed algorithm. This provides reliable technical support for marine electromagnetic scattering simulation and related engineering applications.

[0115] In particular, in some preferred embodiments of the present invention, a computer device is also provided, including a memory and a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors described in any of the above embodiments.

[0116] In some other preferred embodiments of the present invention, a computer-readable storage medium is also provided, on which a computer program / instruction is stored, wherein when the computer program is executed by a processor, the steps of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors described in any of the above embodiments are implemented.

[0117] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above embodiments of the multi-scale sea surface electromagnetic scattering calculation method based on marine environmental factors, which will not be repeated here.

[0118] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0119] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0120] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more N executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of the invention pertain.

[0121] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0122] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0123] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0124] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0125] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors, characterized in that, include: Step 1: Calculate the tension wave spectrum based on the Elfouhaily sea spectrum combined with the Longuet-Higgins directional spectrum; Step 2: Calculate the gravitational wave spectrum using the JONSWAP sea spectrum combined with the Longuet-Higgins directional spectrum; Step 3: Use the linear superposition method to superimpose the tension wave onto the gravity wave according to the slope, and calculate the adaptive cutoff wave number; Step 4: Calculate the contribution of small-scale waves to scattering using the integral equation method and statistically analyze the specular scattering of large-scale waves using the Kirchhoff approximation method. Statistically fuse the waves at each scale based on the adaptive truncation wavenumber to obtain the electromagnetic scattering value.

2. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In steps 1 and 2, the Longuet-Higgins directional spectrum is expressed in one-sided cosine form as follows: Among them, c m To obtain the curvature spectrum gravity-capillary peak value k m The minimum phase velocity at time t; s is a parameter controlling propagation; Wave direction angle; c represents the wind direction; c represents the wave phase velocity; c p =c(k p ) represents the phase velocity at the peak of the spectrum.

3. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 2, characterized in that, In step 1, the Elfouhaily spectral expression is: S E (k)=k -3 [B l (k)+B h (k)] Among them, S E (k) represents the Elfouhaily sea surface spectrum; B l B h Let B = k be the low-frequency curvature spectrum corresponding to gravity waves and the high-frequency curvature spectrum corresponding to tension waves. 3 S, k is the incident wave number, S is the energy spectrum; B h (k)=0.5α m c m F m / c F m =exp[-1.25(k / k p ) -2 ]exp[-0.25(k / k m -1) 2 ] Among them, F m The shortwave action function; frictional wind speed u f The unit is m / s; The tension wave spectrum S capillary for:

4. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 2, the wave number spectrum of the JONSWAP sea spectrum is: Among them, H s Significant wave height; T p γ is the peak period; γ is the peak elevation factor; the dimensionless spectral width parameter σ1 is expressed as: Where f is the frequency domain; f p The frequency of the spectral peak; The gravity wave spectrum S gravity for:

5. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 3, the step of superimposing Zhang Libo onto the gravity wave according to the slope is as follows: z=η gravity (x,y,t)+η capillary (x,y,t)+Z x x+Z y y Where z represents the height fluctuation of the superimposed waves; η gravity (x,y,t) represents the height variation of the center of the gravity wave surface element in the multi-scale marine environmental element; η capillary (x,y,t) represents the amplitude values ​​of tension waves, a multi-scale marine environmental element; (x,y) represents the positional coordinate vectors of microstructures within the tension wave surface element; Z x and Z y These are the slopes of the gravitational wave in the x and y directions, respectively. Where, η gravity (x,y,t) and η capillary (x,y,t) is obtained by calculating η(x,y,t), where Select either tension wave spectroscopy or gravity wave spectroscopy; ω i Angular frequency; ∈ ij This is the initial random phase.

6. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 3, the adaptive truncation wavenumber k cut for: Wherein, S(K) is the wave height fluctuation z obtained by Fourier transform after superposition.

7. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 4, the contribution of small-scale waves to scattering after adaptive truncation wavenumber partitioning is calculated using the integral equation method: Where, θ i σ is the angle of incidence; σ is the standard deviation of surface roughness; f PQ F PQ Represents the polarization factor f vv ,f hh The polarization factors F under VV and HH polarizations are respectively. vv ,F hh These are the polarization factors under VV and HH polarization, respectively.

8. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 4, the Kirchhoff approximation method is used to calculate the contribution of large-scale waves to scattering after adaptive truncation wavenumber partitioning: Where, θ s It is the scattering angle; q is the phase factor; Z is the scattering angle. x =-q x / q z Z y =-q z ;U pQ P(Z) represents the polarization coefficient; x Z y ) is a slope probability density function on a large scale.

9. The calculation method for multi-scale sea surface electromagnetic scattering based on marine environmental factors according to claim 1, characterized in that, In step 4, the wave statistics at each scale are statistically fused based on the adaptive truncation wavenumber as follows: Wherein, <·> represents the ensemble average of the scattering contribution of small-scale waves based on the sea surface slope determined by large-scale waves.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 9.

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