A method, device and equipment for decomposing the direction of internal solitary waves based on time-space Fourier transform

Abstract

The present application relates to a method, device and equipment for decomposing the direction of internal solitary waves based on time-space Fourier transform, and relates to the technical field of marine internal wave signal processing. The method comprises: performing time Fourier transform processing on a parameter time series corresponding to the numerical simulation result of the internal solitary wave obtained, obtaining a target frequency domain signal containing the target positive frequency of the internal solitary wave signal in each fluctuation component, performing two-dimensional space Fourier transform processing on the target frequency domain signal, obtaining target wave number domain information, the target wave number domain information containing the internal wave information in a specific direction, performing inverse Fourier transform on the target wave number domain information, obtaining a target internal solitary wave signal propagating in the target direction. The present application makes full use of Fourier transform, and realizes separation of multi-directional internal solitary waves by filtering the internal solitary wave signal in the frequency domain and the wave number domain, thereby solving the problem that the prior art cannot accurately separate the internal solitary waves.

Description

Technical Field

[0001] The present application relates to the technical field of ocean internal wave signal processing, and in particular to a method, device and equipment for decomposing the direction of internal solitary waves based on time-space Fourier transform. Background Art

[0002] In related technologies, internal solitary waves, as an important dynamic process in the ocean, have strong nonlinear fluctuation characteristics such as short period (several minutes to tens of minutes), large amplitude (tens to hundreds of meters), and are widely present in various seas around the world. Over the past few decades, with the rapid development of ocean numerical models, research on the generation mechanism, evolution law, dissipation process, and spatiotemporal distribution characteristics of internal solitary waves has received widespread attention from scientific researchers at home and abroad. However, the sources of internal waves in the real ocean are numerous, and the variables output by numerical simulations (temperature disturbances, wave-induced velocity, sea surface height anomalies, etc.) often contain internal wave information propagating in different directions.

[0003] Whether it is a linear internal tide or a nonlinear internal solitary wave, decomposing the incident wave and reflected wave signals in a regional model is necessary to clarify the physical laws of its propagation process. Existing schemes are mainly used for linear internal tide separation, including: coupling models of the Laplace tidal equation, numerical experiments on sensitivity by comparing the presence or absence of continental slope terrain, application of two-dimensional plane wave fitting in satellite products, and application of Hilbert transform. However, due to the strong nonlinear characteristics of internal solitary waves, existing schemes are not suitable for internal solitary waves, especially in the complex case of multiple waves superposition, and the physical process is not fully understood. Therefore, there is still a lack of accurate separation methods for multi-directional internal solitary waves, and existing technologies cannot accurately separate internal solitary waves. Summary of the invention

[0004] The present application provides a method, device and equipment for decomposing the direction of internal solitary waves based on time-space Fourier transform, which makes full use of Fourier transform and realizes the separation of multi-directional internal solitary waves by filtering the internal solitary wave signals in the frequency domain and the wavenumber domain. It can effectively distinguish the components propagating in different directions in the wave signal, and can accurately separate both the internal solitary waves propagating toward the shore and the internal solitary waves reflected from the shore, thus solving the problem that the existing technology cannot accurately separate the internal solitary waves.

[0005] In a first aspect, the present application provides a method for decomposing the direction of an internal solitary wave based on time-space Fourier transform, comprising:

[0006] Obtain numerical simulation results of internal solitary waves in ocean areas;

[0007] Performing a time Fourier transform process on the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal, wherein the target frequency domain signal includes a target positive frequency of the inner solitary wave in each wave component;

[0008] Performing a two-dimensional spatial Fourier transform process on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information includes internal wave information in a specific direction;

[0009] An inverse Fourier transform is performed based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction.

[0010] Optionally, performing a time Fourier transform process on the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal includes:

[0011] Extracting parameter time series according to the numerical simulation results;

[0012] Performing time Fourier transform and zero-filling processing according to the parameter time series to obtain frequency domain information of the internal solitary wave in each wave component;

[0013] Perform negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal;

[0014] Wherein, the obtaining of the numerical simulation result of the internal solitary wave in the ocean area includes: performing calculations through a preset numerical model to obtain the internal solitary wave signal as the numerical simulation result.

[0015] Optionally, performing two-dimensional spatial Fourier transform processing on the target frequency domain signal to obtain target wavenumber domain information includes:

[0016] Performing a two-dimensional spatial Fourier transform based on the target frequency domain signal to obtain wave number domain data;

[0017] Acquire a horizontal wave number ratio and a preset target direction, wherein the target direction includes an angle interval;

[0018] generating a filter function according to the horizontal wave number ratio and the target direction;

[0019] Based on the filter function, non-target wavenumbers are filtered out from the wavenumber domain data to obtain target wavenumber domain information in a specific direction.

[0020] Optionally, performing a time Fourier transform and a zero-filling process on the parameter time series to obtain frequency domain information of the internal solitary wave in each wave component includes:

[0021] according to Perform time Fourier transform to obtain the frequency domain of each wave component of the internal solitary wave converted from the time domain to the frequency domain;

[0022] Improving the frequency resolution by zero-filling technology to obtain the frequency domain information;

[0023] Among them, η(x,y,ω) is the parameter time series, is the frequency domain obtained by Fourier transform of the parameter time series, and ω is the frequency of each fluctuation component.

[0024] Optionally, performing negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal includes:

[0025] Filtering out negative frequencies from the frequency domain information to obtain positive frequency components;

[0026] The positive frequency component is multiplied by Fourier coefficients to obtain a target frequency domain signal, wherein the amplitude of the fluctuation signal of the target frequency domain signal is consistent with the amplitude of the original signal.

[0027] Optionally, generating a filter function according to the horizontal wave number ratio and the target direction includes:

[0028] according to Generate filter function;

[0029] Among them, the filter function ζ(k,l) is used as a filter to select the wave signal in the target direction to separate the waves propagating in different directions. l / k is the horizontal wave number ratio in the wave number domain. θ1 and θ2 are the directional angle cutoff values ​​of the filter, which are used to determine the propagation direction range of the decomposed inner solitary wave.

[0030] Optionally, filtering out non-target wavenumbers from the wavenumber domain data based on the filter function to obtain target wavenumber domain information in a specific direction includes:

[0031] according to Directional filters are applied to the wavenumber domain signals to obtain information on fluctuations in the target direction only, while fluctuations in non-target directions are filtered out.

[0032] in, It is the wave number domain data obtained by converting the target frequency domain signal from the spatial domain (x, y) to the wave number domain (k, l).

[0033] Optionally, performing an inverse Fourier transform according to the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction includes:

[0034] according to The signal in the wave number domain is returned to the space-time domain through inverse Fourier transform to obtain the space-time fluctuation signal of the internal solitary wave in a specific direction as the target internal solitary wave signal.

[0035] In a second aspect, the present application provides an internal solitary wave direction decomposition device based on time-space Fourier transform, comprising:

[0036] A numerical simulation result acquisition module is used to obtain numerical simulation results of internal solitary waves in the ocean area;

[0037] A time transform processing module is used to perform time Fourier transform processing according to the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal, wherein the target frequency domain signal includes the target positive frequency of the inner solitary wave in each fluctuation component;

[0038] A spatial transformation processing module is used to perform a two-dimensional spatial Fourier transform processing on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information includes internal wave information in a specific direction;

[0039] The inverse transform processing module is used to perform inverse Fourier transform according to the target wave number domain information to obtain the target internal solitary wave signal propagating in the target direction.

[0040] In a third aspect, the present application provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus;

[0041] Memory, used to store computer programs;

[0042] The processor is used to implement the steps of the internal solitary wave direction decomposition method based on space-time Fourier transform as described in any embodiment of the first aspect when executing the program stored in the memory.

[0043] In summary, the embodiment of the present application obtains the numerical simulation results of internal solitary waves in the ocean area, performs time Fourier transform processing according to the parameter time series corresponding to the numerical simulation results, obtains the target frequency domain signal containing the target positive frequency of the internal solitary wave signal in each fluctuation component, performs two-dimensional spatial Fourier transform processing according to the target frequency domain signal, obtains the target wavenumber domain information, the target wavenumber domain information contains the internal wave information in a specific direction, performs inverse Fourier transform according to the target wavenumber domain information, and obtains the target internal solitary wave signal propagating in the target direction. The present application utilizes the space-time Fourier filter method to filter the internal solitary wave signal in the frequency domain and the wavenumber domain, so that both the waves propagating toward the shore and the waves reflected from the shore can be accurately separated, and the separation of multi-directional internal solitary waves can be achieved for the superimposed waves in the complex terrain, thereby solving the problem that the prior art cannot accurately separate the internal solitary waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0046] Figure 1 A schematic flow chart of a method for decomposing the direction of an internal solitary wave based on spatiotemporal Fourier transform provided in an embodiment of the present application;

[0047] Figure 2 It is a schematic flow chart of the steps of a method for decomposing the direction of an internal solitary wave based on time-space Fourier transform provided by an optional embodiment of the present application;

[0048] Figure 3 is a flow chart of the direction decomposition of the internal solitary wave of Fourier transform provided by an optional embodiment of the present application;

[0049] Figure 4 It is a schematic diagram of space-time-spectrum Fourier transformation provided by an optional example of the present application;

[0050] Figure 5 It is a schematic diagram of the root mean square error of the amplitude of the extracted solitary waves propagating in different directions provided by an optional example of the present application;

[0051] Figure 6 A structural block diagram of an internal solitary wave direction decomposition device based on spatiotemporal Fourier transform provided in an embodiment of the present application;

[0052] Figure 7 It is a structural schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0054] To facilitate the understanding of the embodiments of the present application, further explanation will be given below in conjunction with the drawings and specific embodiments. The embodiments do not constitute a limitation on the embodiments of the present application.

[0055] Figure 1 The present invention provides a flow chart of a method for decomposing the direction of an internal solitary wave based on a spatiotemporal Fourier transform. Figure 1 As shown, the internal solitary wave direction decomposition method based on spatiotemporal Fourier transform provided in the embodiment of the present application may specifically include the following steps:

[0056] Step 110, obtaining numerical simulation results of internal solitary waves in the ocean area.

[0057] In this embodiment, the numerical simulation result includes an internal solitary wave signal, and the internal solitary wave signal may include but is not limited to: internal wave information propagating in different directions.

[0058] It should be noted that, in this embodiment, the internal solitary wave signal can be a real internal solitary wave generated by the ocean area, or can be a reconstructed internal solitary wave obtained by numerical simulation using a numerical model. Therefore, in this embodiment, the ocean area can be detected to obtain the internal solitary wave signal, or the internal solitary wave signal can be calculated using a numerical model.

[0059] In an optional embodiment, the embodiment of the present application obtains numerical simulation results of internal solitary waves in an ocean area, which may specifically include: performing calculations through a preset numerical model to obtain internal solitary wave signals as numerical simulation results.

[0060] In a specific implementation, this embodiment can pre-construct a numerical model and obtain the internal solitary wave signal through numerical model calculation.

[0061] Step 120, performing time Fourier transform processing on the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal.

[0062] The target frequency domain signal includes the target positive frequency of the inner solitary wave in each fluctuation component.

[0063] In this embodiment, the parameter time series corresponding to the numerical simulation results refers to the time series of two-dimensional (horizontal) internal solitary wave parameters, referred to as time series for short.

[0064] In a specific implementation, when internal solitary waves propagate on the continental slope, they may encounter islands (such as the Dongsha Islands in the South China Sea), thereby triggering a variety of physical processes such as reflection, diffraction, and interaction between waves. Related studies have pointed out that the reflected internal solitary wave signals have a small amplitude and are often difficult to observe in satellite images because they quickly dissipate wave energy in a short distance and are not strong enough to be detected. However, in large-amplitude internal solitary wave events, reflected waves are more easily captured in satellite images. Since incident internal solitary waves are usually stronger than reflected internal solitary waves, reflected wave signals are difficult to capture when other incident waves related to the next tidal cycle are superimposed. As a result, the existing scheme cannot accurately extract internal solitary waves propagating in different directions, lacks quantitative analysis of reflected waves on different time scales, and thus affects the comprehensive understanding of the wave process. In order to solve the defects of the existing scheme, this embodiment uses the studied ocean area as the target area for internal solitary wave detection, so as to obtain the internal solitary wave signal of the ocean area. Subsequently, the internal solitary wave signal can be identified and processed to obtain the two-dimensional internal solitary wave parameters corresponding to the internal solitary wave signal. By extracting and processing the two-dimensional internal solitary wave parameters, a time series is obtained, thereby converting the internal solitary wave signal into the time domain for processing to obtain the time series of the internal solitary wave signal in the time domain.

[0065] In this embodiment, after obtaining the parameter time series corresponding to the internal solitary wave signal, the time series can be used to perform a time Fourier transform to convert the signal from the time domain to the frequency domain, and obtain the frequency domain signal (or simply the frequency domain, frequency domain data, etc.) of the internal solitary wave signal in the frequency domain, thereby realizing the use of the frequency domain to express the various propagation directions of the internal solitary wave signal. As a result, the embodiment of the present application realizes the accurate extraction of internal solitary waves propagating in different directions, realizes the quantitative analysis of internal solitary waves on different time scales, and provides a basis for a comprehensive understanding of the wave process.

[0066] In actual implementation, the frequency domain signal usually contains positive frequencies and negative frequencies. This embodiment can filter out the negative frequencies in the frequency domain signal and retain only the positive frequencies, thereby obtaining the target positive frequencies of the inner solitary wave signal in each fluctuation component, and further obtaining the target frequency domain signal.

[0067] Step 130, performing two-dimensional spatial Fourier transform processing on the target frequency domain signal to obtain target wave number domain information.

[0068] The target wavenumber domain information includes internal wave information in a specific direction.

[0069] In this embodiment, after obtaining the target frequency domain signal with the negative frequency components eliminated, the signal after the time Fourier transform can be further subjected to a two-dimensional spatial Fourier transform to convert the target frequency domain signal from the spatial domain to the wave number domain. By performing a two-dimensional spatial Fourier transform operation, the wave number domain information in the two-dimensional wave number domain is obtained.

[0070] In a specific implementation, in order to separate the waves propagating in different directions, this embodiment can separate and select the acquired wave number domain information, by presetting a target direction to select the wave number in the target direction, filtering the wave number domain in the non-target direction, and realizing the separation and selection of the wave signal to obtain the target wave number domain information. Therefore, this embodiment realizes the separation of waves in different directions by selecting the wave number, thereby clarifying the components of the internal solitary wave on different propagation paths.

[0071] Step 140, performing an inverse Fourier transform based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction.

[0072] In this embodiment, after separation and selection through two-dimensional Fourier transform, the directional decomposition is completed, and then the signal in the target wave number domain information can be returned to the space-time domain through inverse Fourier transform, and the space-time fluctuation signal of the internal solitary wave in a specific direction can be restored to obtain the target internal solitary wave signal propagating in the target direction.

[0073] It can be seen that the embodiment of the present application obtains the numerical simulation results of internal solitary waves in the ocean area, performs time Fourier transform processing according to the parameter time series corresponding to the numerical simulation results, obtains the target frequency domain signal containing the target positive frequency of the internal solitary wave signal in each fluctuation component, performs two-dimensional spatial Fourier transform processing according to the target frequency domain signal, obtains the target wavenumber domain information, the target wavenumber domain information contains the internal wave information in a specific direction, performs inverse Fourier transform according to the target wavenumber domain information, and obtains the target internal solitary wave signal propagating in the target direction. The present application utilizes the space-time Fourier filter method to filter the internal solitary wave signal in the frequency domain and the wavenumber domain, so that both the waves propagating toward the shore and the waves reflected from the shore can be accurately separated, and the separation of multi-directional internal solitary waves can be achieved for the superimposed waves in the complex terrain, thereby solving the problem that the prior art cannot accurately separate the internal solitary waves.

[0074] Reference Figure 2 , shows a schematic flow chart of the steps of a method for decomposing the direction of an internal solitary wave based on time-space Fourier transform provided by an optional embodiment of the present application. The method may specifically include the following steps:

[0075] Step 210, obtaining numerical simulation results of internal solitary waves in the ocean area.

[0076] Step 220: extracting parameter time series according to the numerical simulation results.

[0077] In this embodiment, the two-dimensional internal solitary wave parameters may include, but are not limited to: temperature disturbance, pressure disturbance, wave-induced flow velocity, and sea surface height anomaly. The parameter time series may include the extracted and converted information of each parameter in the two-dimensional internal solitary wave parameters. In this embodiment, the parameter time series may be extracted from the numerical simulation results.

[0078] Step 230, performing time Fourier transform and zero-filling processing according to the parameter time series to obtain frequency domain information of the internal solitary wave in each wave component.

[0079] In the specific implementation, refer to Figure 3 In this embodiment, the parameter time series is converted from the time domain to the frequency domain by performing a time Fourier transform on the parameter time series to extract the frequency of each fluctuation component. Then, the frequency domain resolution is improved by zero-padding technology, so as to more accurately analyze the complex amplitude of the space at different frequencies.

[0080] In an optional embodiment, the embodiment of the present application performs a time Fourier transform and a zero-filling process according to the parameter time series to obtain the frequency domain information of the internal solitary wave signal in each fluctuation component, which may specifically include: Perform time Fourier transform to obtain the frequency domain of each wave component of the internal solitary wave converted from the time domain to the frequency domain; improve the resolution of the frequency by zero filling technology to obtain the frequency domain information; wherein η(x, y, ω) is a parameter time series, is the frequency domain obtained by Fourier transform of the parameter time series, and ω is the frequency of each fluctuation component.

[0081] In a specific implementation, in order to accurately analyze the spatial complex amplitude at different frequencies, this embodiment uses the specific expression of Fourier transform: Through this expression, the signal of the parameter time series is first converted from the time domain to the frequency domain, and the frequency of each fluctuation component is extracted. Finally, the zero-sum filling technique is used to improve the frequency domain resolution.

[0082] Therefore, this embodiment accurately analyzes the spatial complex amplitudes at different frequencies, thereby improving the accuracy of subsequent directional decomposition of the internal solitary waves.

[0083] Step 240: Perform negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal.

[0084] The target frequency domain signal includes the target positive frequency of the inner solitary wave in each fluctuation component.

[0085] In the specific implementation, refer to Figure 3 The frequency domain signal obtained by time Fourier transform contains positive frequency and negative frequency components. The negative frequency part usually corresponds to the symmetrical part of the signal. To simplify the analysis, this embodiment can filter out the negative frequency and only retain the positive frequency component. The negative frequency can be filtered out by referring to Figure 4 shown.

[0086] In an optional embodiment, the embodiment of the present application performs negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal, which may specifically include: filtering out negative frequencies from the frequency domain information to obtain positive frequency components; multiplying the positive frequency components by Fourier coefficients to obtain a target frequency domain signal, wherein the amplitude of the fluctuation signal of the target frequency domain signal is consistent with the amplitude of the original signal.

[0087] In the specific implementation, this embodiment uses Negative frequencies are filtered out to obtain a frequency domain containing positive frequency components. After filtering out the negative frequencies, in order to ensure that the amplitude of the fluctuation signal is consistent with the amplitude of the original signal, this embodiment can multiply the Fourier coefficient of the positive frequency by 2 to obtain the target frequency domain signal, that is,

[0088] Step 250: Perform a two-dimensional spatial Fourier transform based on the target frequency domain signal to obtain wave number domain data.

[0089] In this embodiment, after eliminating the negative frequency component, the signal after the time Fourier transform can be subjected to a two-dimensional spatial Fourier transform, and the target frequency domain signal can be converted from the spatial domain (x, y) to the wave number domain (k, l) to obtain wave number domain data. This embodiment uses a two-dimensional spatial Fourier transform to obtain the wave expression in the two-dimensional wave number domain: This wave expression can be used as wavenumber domain data for subsequent processing.

[0090] Step 260, obtaining a horizontal wave number ratio and a preset target direction, wherein the target direction includes an angle interval.

[0091] Step 270: Generate a filter function according to the horizontal wave number ratio and the target direction.

[0092] A unified description of steps 260 to 270 is given as follows:

[0093] In this embodiment, the target direction may include two directional angle cutoff values. By setting the target direction, the wave signal in a certain direction can be selected. Exemplarily, the two directional angle cutoff values ​​may be set to θ1 and θ2, respectively, wherein the specific values ​​of the two directional angles may be set according to actual needs, and this example does not limit them. The horizontal wave number ratio may be understood as the wave number ratio between the two directional angles.

[0094] It should be noted that, in this embodiment, the step of performing two-dimensional spatial Fourier transform based on the target frequency domain signal and the step of generating a filter function can be executed in parallel or sequentially, and this embodiment does not impose any limitation on this.

[0095] In the specific implementation, in order to solve the problem that the existing technology is insufficient in handling multi-directional fluctuations and to achieve the separation of fluctuations propagating in different directions, one of the innovations of this embodiment is that a new type of space-time Fourier filter is proposed. By presetting the horizontal wavenumber ratio and the target direction, a filter function is defined using the horizontal wavenumber ratio and the target direction as a directional filter, and the filter is then used to select the fluctuation signal in the target direction.

[0096] In an optional embodiment, the embodiment of the present application generates a filter function according to the horizontal wave number ratio and the target direction, which may specifically include:

[0097] according to Generate a filter function; the filter function ζ(k,l) is used as a filter to select the wave signal in the target direction to separate the waves propagating in different directions. l / k is the horizontal wave number ratio in the wave number domain. θ1 and θ2 are the directional angle cutoff values ​​of the filter, which are used to determine the propagation direction range of the decomposed inner solitary wave.

[0098] In order to reasonably use the filter ζ(k, l) to select the fluctuation signal, this embodiment selects the propagation direction range of the inner solitary wave through the above formula.

[0099] Step 280 , filtering out non-target wavenumbers from the wavenumber domain data based on the filter function to obtain target wavenumber domain information in a specific direction.

[0100] In the specific implementation, refer to Figure 3 Due to the internal wave dispersion relationship, its propagation direction [θ1, θ2] in the spatial domain can be effectively converted into the horizontal wavenumber ratio l / k in the wavenumber domain. Therefore, in this embodiment, the wavenumber domain data can be filtered out by a filter, the wavenumber ratio between [tan(θ1), tan(θ1)] is retained, and the signals in other wavenumber domains are filtered out to obtain only the wave information in the target direction as the target wavenumber domain information. Among them, the wavenumber ratios other than [tan(θ1), tan(θ1)] can be filtered out as non-target wavenumbers.

[0101] In the related technologies, the existing technologies still have problems such as: complex internal wave field characteristics caused by the superposition of internal solitary waves in different directions in numerical simulation results, insufficient adaptability under complex terrain conditions, insufficient weak signal detection / capture capabilities, and multi-wave superposition and interference.

[0102] Specifically, in response to the complex internal wave field characteristics caused by the superposition of internal solitary waves in different directions in the existing numerical simulation results, this embodiment proposes an internal solitary wave directional decomposition method based on time-space Fourier transform, which effectively distinguishes the amplitudes of internal solitary waves in different propagation directions in the numerical model, and clarifies the incidence, reflection and dissipation processes of internal solitary waves in the continental slope and island and reef waters.

[0103] Lack of adaptability under complex terrain conditions refers to: complex marine environments (such as islands, steep continental slopes, continental shelves, etc.) usually produce complex reflections, diffractions and wave interactions on waves. Under these complex terrains, existing linear internal tide decomposition technologies, such as the Laplace Tidal Equation Coupled Model (CELT) or the two-dimensional plane wave fitting method, cannot effectively resolve the multi-wave propagation problem, and there is a problem of insufficient adaptability under complex terrain conditions. In view of the problem of insufficient adaptability under complex terrain conditions in the prior art, the directional decomposition method of the embodiment of the present application can adapt to these complex environments. Through multi-directional decomposition in the wave number domain, it can not only identify internal solitary waves propagating in multiple directions, but also quantify the wave energy and interaction in each direction. For the wave characteristics in specific geographical environments, such as the Dongsha Islands in the South China Sea, it has significant technical advantages.

[0104] Insufficient weak signal detection / capture capability means that small-amplitude reflected waves quickly dissipate energy over a short distance, causing these signals to be often ignored in satellite observations or numerical simulations. Existing technologies have difficulty in capturing weak reflected waves. In response to the problem of insufficient weak signal detection / capture capability in the prior art, this embodiment can more clearly separate and identify these weak signals through a spatiotemporal Fourier filter, even if they are superimposed or masked by stronger incident waves. For reflected wave energy that is difficult to detect with the prior art, the signal-to-noise ratio can be significantly improved after using the directional decomposition method, thereby better tracking the complete path of the wave energy and improving the accuracy of the numerical simulation and the degree of matching with the actual observation results.

[0105] Problems such as multi-wave superposition and interference refer to the following: during a tidal cycle, internal solitary waves and other wave signals often overlap and interfere with each other, especially the overlap of incident waves and reflected waves. It is difficult for existing technologies to accurately identify the components of each independent wave in this case. In view of the problem that it is difficult to accurately identify the components of each independent wave in the existing technology, this embodiment can extract the superimposed wave signals separately through the joint decomposition of frequency and wave number, avoiding the complexity caused by interference from different waves. The multi-wave decomposition technology provided in this embodiment provides a powerful tool for studying multi-wave interactions in complex environments, especially under geographical conditions such as islands and continental slopes. It can better study how internal solitary waves are affected by the environment and further promote the understanding of nonlinear wave processes.

[0106] Therefore, in this embodiment, the filtered signal only contains the fluctuation information in the target direction, while the fluctuations in other directions are filtered out. The separation of fluctuations in different directions is achieved by selecting the wave number, and the components of the internal isolated waves in different propagation paths are clarified. By using the directional decomposition method, the signal-to-noise ratio can be significantly improved, thereby better tracking the complete path of the fluctuation energy. This is of great significance for improving the accuracy of numerical simulation and the matching degree with actual observation results.

[0107] In an optional embodiment, the embodiment of the present application performs non-target wavenumber filtering on the wavenumber domain data based on the filter function to obtain target wavenumber domain information in a specific direction, which may specifically include: The directional filter is applied to the wavenumber domain signal to obtain the fluctuation information only in the target direction, and the fluctuation in the non-target direction is filtered out; It is the wave number domain data obtained by converting the target frequency domain signal from the spatial domain (x, y) to the wave number domain (k, l).

[0108] In a specific implementation, in order to accurately utilize the filter, the wave number is selected to achieve separation of fluctuations in different directions, thereby filtering out the fluctuation information in non-target directions from the wave number domain signal. This embodiment defines a formula for utilizing the filter: This formula is used to separate waves propagating in different directions.

[0109] Step 290, performing an inverse Fourier transform based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction.

[0110] In this embodiment, refer to Figure 3 After the directional decomposition is completed, the signal in the wave number domain can be returned to the time and space domain through the inverse Fourier transform to restore the time and space fluctuation signal of the internal solitary wave in a specific direction. In this embodiment, the signal obtained by the inverse Fourier transform represents the time and space evolution characteristics of the internal solitary wave in the selected direction. At this time, only the propagation information in the target direction is retained in the fluctuation signal, and the fluctuations in other directions are effectively filtered out.

[0111] In an optional embodiment, the embodiment of the present application performs an inverse Fourier transform based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction, which may specifically include: The signal in the wave number domain is returned to the space-time domain through inverse Fourier transform to obtain the space-time fluctuation signal of the internal solitary wave in a specific direction as the target internal solitary wave signal.

[0112] In this embodiment, after the separation of the waves in different directions is completed, in order to restore the space-time wave signal of the inner solitary wave in a specific direction, the inverse Fourier formula is used to transform the signal from the wave number domain to the space-time domain.

[0113] Therefore, the present application converts the wave signal into the frequency-wave number domain through the spatiotemporal Fourier transform, removes the negative frequency components and further performs a two-dimensional spatial Fourier transform on the positive frequency components, defines the filter function in the wave number domain, and thus obtains the internal solitary wave signal in the target direction. At the same time, the technology can adapt to complex terrain environments (such as continental slopes and islands), effectively capture the reflection, diffraction and interaction processes of waves, and support quantitative analysis of internal solitary waves in specific directions, calculate key parameters such as wave energy and amplitude, and provide an efficient and accurate tool for studying the propagation process of internal solitary waves in complex marine environments.

[0114] For example, refer to Figure 5 , Figure 5 The evaluation results of the internal solitary wave directional decomposition method provided in this application under different numerical model time and spatial resolution requirements are shown. Figure 5 The reliability of the spatiotemporal Fourier transform method is demonstrated in the case of superposition of different internal solitary wave amplitudes and half-wave widths. Figure 5 The horizontal axis in the figure represents the normalized spatial resolution, and the vertical axis represents the normalized temporal resolution. The colors represent the relative root mean square error (RMSE) between the two-way forcing model and the one-way forcing model, and the dashed contour lines represent the correlation coefficient. Figure 5 As shown in the figure, the relative root mean square error in most areas is always less than 0.05, and the correlation coefficient is greater than 0.98. In summary, whether it is an internal solitary wave train or a single solitary wavelet, when the time and space sampling rate is less than half the wave width and the characteristic wavelength, the spatiotemporal Fourier filtering method can accurately decompose the internal solitary wave signals propagating in different directions.

[0115] In summary, the embodiment of the present application obtains the numerical simulation results of the internal solitary wave in the ocean area, extracts the parameter time series through the numerical simulation results, performs time Fourier transform and zero filling processing according to the parameter time series, obtains the frequency domain information of each wave component of the internal solitary wave signal, and performs negative frequency filtering processing according to the frequency domain information to obtain the target frequency domain signal, and then performs two-dimensional spatial Fourier transform based on the target frequency domain signal to obtain wave number domain data, and obtains the horizontal wave number ratio and the preset target direction, the target direction includes an angle interval, generates a filter function according to the horizontal wave number ratio and the target direction, and performs non-target wave number filtering on the wave number domain data based on the filter function to obtain the target wave number domain information in a specific direction, performs inverse Fourier transform according to the target wave number domain information, and obtains the target internal solitary wave signal propagating in the target direction. The internal solitary wave direction decomposition method provided in the embodiment of the present application uses the space-time Fourier filter technology to solve the problem that the existing technology cannot accurately perform internal solitary wave decomposition, and breaks through the limitations of the existing technology in multi-directional nonlinear wave decomposition, energy quantization and weak signal detection. Compared with the prior art, the embodiments of the present application provide more refined directional separation, enhance the ability to capture weak wave energy, and adapt to the wave characteristics in complex terrain and environment. It not only improves the understanding of internal solitary waves, but also provides new scientific tools for the improvement of regional ocean models, the quantification of ocean energy transmission, and the study of wave processes under complex terrain.

[0116] It should be noted that, for the purpose of simple description, the method embodiments are expressed as a series of action combinations, but those skilled in the art should be aware that the embodiments of the present application are not limited to the described order of actions, because according to the embodiments of the present application, certain steps may be performed in other orders or simultaneously.

[0117] like Figure 6 As shown, the embodiment of the present application further provides an internal solitary wave direction decomposition device 600 based on time-space Fourier transform, comprising:

[0118] A numerical simulation result acquisition module 610 is used to acquire numerical simulation results of internal solitary waves in an ocean area;

[0119] A time transform processing module 620 is used to perform time Fourier transform processing according to the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal, wherein the target frequency domain signal includes the target positive frequency of the inner solitary wave in each fluctuation component;

[0120] A spatial transformation processing module 630 is used to perform a two-dimensional spatial Fourier transform process on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information includes internal wave information in a specific direction;

[0121] The inverse transform processing module 640 is used to perform an inverse Fourier transform based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction.

[0122] Optionally, the time transformation processing module 620 includes:

[0123] A parameter time series determination submodule is used to extract a parameter time series according to the numerical simulation results;

[0124] A time transformation and filling processing submodule is used to perform time Fourier transformation and zero filling processing according to the parameter time series to obtain the frequency domain information of the internal solitary wave in each wave component;

[0125] A frequency filtering submodule, used for performing negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal;

[0126] Wherein, the obtaining of the numerical simulation result of the internal solitary wave in the ocean area includes: performing calculations through a preset numerical model to obtain the internal solitary wave signal as the numerical simulation result.

[0127] Optionally, the space transformation processing module 630 includes:

[0128] A two-dimensional spatial Fourier transform submodule is used to perform a two-dimensional spatial Fourier transform based on the target frequency domain signal to obtain wave number domain data;

[0129] The wave number ratio and direction acquisition submodule is used to acquire the horizontal wave number ratio and a preset target direction, wherein the target direction includes an angle interval;

[0130] A filter function generating submodule, used for generating a filter function according to the horizontal wave number ratio and the target direction;

[0131] The wavenumber filtering submodule is used to filter out non-target wavenumbers on the wavenumber domain data based on the filtering function to obtain target wavenumber domain information in a specific direction.

[0132] Optionally, the time conversion and filling processing submodule is specifically used to: Perform time Fourier transform to obtain the frequency domain of each wave component of the internal solitary wave converted from the time domain to the frequency domain; improve the resolution of the frequency by zero filling technology to obtain the frequency domain information; wherein η(x, y, ω) is a parameter time series, is the frequency domain obtained by Fourier transform of the parameter time series, and ω is the frequency of each fluctuation component.

[0133] Optionally, the frequency filtering submodule includes:

[0134] A negative frequency filtering unit, used to filter out negative frequencies from the frequency domain information to obtain positive frequency components;

[0135] The Fourier coefficient multiplication unit is used to perform Fourier coefficient multiplication on the positive frequency component to obtain a target frequency domain signal, wherein the amplitude of the fluctuation signal of the target frequency domain signal is consistent with the amplitude of the original signal.

[0136] Optionally, the filter function generation submodule is specifically used to:

[0137] Generate a filter function; the filter function ζ(k,l) is used as a filter to select the wave signal in the target direction to separate the waves propagating in different directions. l / k is the horizontal wave number ratio in the wave number domain. θ1 and θ2 are the directional angle cutoff values ​​of the filter, which are used to determine the propagation direction range of the decomposed inner solitary wave.

[0138] Optionally, the wave number filtering submodule is specifically used to: The directional filter is applied to the wavenumber domain signal to obtain the fluctuation information only in the target direction, and the fluctuation in the non-target direction is filtered out; It is the wave number domain data obtained by converting the target frequency domain signal from the spatial domain (x, y) to the wave number domain (k, l).

[0139] Optionally, the inverse transformation processing module 640 is specifically used to: The signal in the wave number domain is returned to the space-time domain through inverse Fourier transform to obtain the space-time fluctuation signal of the internal solitary wave in a specific direction as the target internal solitary wave signal.

[0140] It should be noted that the internal solitary wave direction decomposition device based on space-time Fourier transform provided in the embodiment of the present application can execute the internal solitary wave direction decomposition method based on space-time Fourier transform provided in any embodiment of the present application, and has the corresponding functions and beneficial effects of executing the internal solitary wave direction decomposition method based on space-time Fourier transform.

[0141] In a specific implementation, the above-mentioned internal solitary wave direction decomposition device based on space-time Fourier transform can be integrated in a device, so that the device can use space-time Fourier filter technology to achieve more refined directional separation, enhance the ability to capture weak wave energy, and adapt to complex terrain and environment. As an electronic device, it can accurately decompose internal solitary wave signals propagating in different directions. The electronic device can be composed of two or more physical entities, or it can be composed of one physical entity. For example, the electronic device can be a personal computer (PC), a computer, a server, etc., and the embodiment of the present application does not impose specific restrictions on this.

[0142] like Figure 7 As shown, an embodiment of the present application provides an electronic device, including a processor 111, a communication interface 112, a memory 113 and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114; the memory 113 is used to store computer programs; the processor 111 is used to implement the steps of the internal solitary wave direction decomposition method based on space-time Fourier transform provided by any of the aforementioned method embodiments when executing the program stored in the memory 113. Exemplarily, the steps of the internal solitary wave directional decomposition method based on time-space Fourier transform may include the following steps: obtaining numerical simulation results of internal solitary waves in an ocean area; performing time Fourier transform processing on a parameter time series corresponding to the numerical simulation results to obtain a target frequency domain signal, wherein the target frequency domain signal contains the target positive frequency of the internal solitary wave in each wave component; performing two-dimensional space Fourier transform processing on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information contains internal wave information in a specific direction; performing inverse Fourier transform on the target wave number domain information to obtain a target internal solitary wave signal propagating in a target direction.

[0143] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the internal solitary wave direction decomposition method based on time-space Fourier transform as provided in any of the aforementioned method embodiments are implemented.

[0144] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0145] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for decomposing the direction of internal solitary waves based on time-space Fourier transform, characterized in that: include: Obtain numerical simulation results of internal solitary waves in ocean areas; Performing a time Fourier transform process on the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal, wherein the target frequency domain signal includes a target positive frequency of the inner solitary wave in each wave component; Performing a two-dimensional spatial Fourier transform process on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information includes internal wave information in a specific direction; An inverse Fourier transform is performed based on the target wave number domain information to obtain a target internal solitary wave signal propagating in the target direction.

2. The method according to claim 1, characterized in that The method of performing a time Fourier transform process on the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal includes: Extracting parameter time series according to the numerical simulation results; Performing time Fourier transform and zero-filling processing according to the parameter time series to obtain frequency domain information of the internal solitary wave in each wave component; Perform negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal; Wherein, the obtaining of the numerical simulation result of the internal solitary wave in the ocean area includes: performing calculations through a preset numerical model to obtain the internal solitary wave signal as the numerical simulation result.

3. The method according to claim 2, characterized in that The step of performing two-dimensional spatial Fourier transform processing on the target frequency domain signal to obtain target wave number domain information includes: Performing a two-dimensional spatial Fourier transform based on the target frequency domain signal to obtain wave number domain data; Acquire a horizontal wave number ratio and a preset target direction, wherein the target direction includes an angle interval; generating a filter function according to the horizontal wave number ratio and the target direction; Based on the filter function, non-target wavenumbers are filtered out from the wavenumber domain data to obtain target wavenumber domain information in a specific direction.

4. The method according to claim 3, characterized in that The method of performing a time Fourier transform and a zero-filling process according to the parameter time series to obtain frequency domain information of the internal solitary wave in each wave component includes: according to Perform time Fourier transform to obtain the frequency domain of each wave component of the internal solitary wave converted from the time domain to the frequency domain; Improving the frequency resolution by zero-filling technology to obtain the frequency domain information; Among them, η(x,y,ω) is the parameter time series, is the frequency domain obtained by Fourier transform of the parameter time series, and ω is the frequency of each fluctuation component.

5. The method according to claim 4, characterized in that The performing negative frequency filtering processing according to the frequency domain information to obtain a target frequency domain signal includes: Filtering out negative frequencies from the frequency domain information to obtain positive frequency components; The positive frequency component is multiplied by Fourier coefficients to obtain a target frequency domain signal, wherein the amplitude of the fluctuation signal of the target frequency domain signal is consistent with the amplitude of the original signal.

6. The method according to claim 3, characterized in that Generate a filter function according to the horizontal wave number ratio and the target direction, including: according to Generate filter function; Among them, the filter function ζ(k, l) is used as a filter to select the wave signal in the target direction to separate the waves propagating in different directions. l / k is the horizontal wave number ratio in the wave number domain, and θ1 and θ2 are the directional angle cutoff values ​​of the filter, which are used to determine the propagation direction range of the decomposed inner solitary wave.

7. The method according to claim 6, characterized in that The filtering of non-target wavenumbers on the wavenumber domain data based on the filter function to obtain target wavenumber domain information in a specific direction includes: according to Directional filters are applied to the wavenumber domain signals to obtain information on fluctuations in the target direction only, while fluctuations in non-target directions are filtered out. in, It is the wave number domain data obtained by converting the target frequency domain signal from the spatial domain (x, y) to the wave number domain (k, l).

8. The method according to claim 7, characterized in that The inverse Fourier transform is performed according to the target wave number domain information to obtain the target internal solitary wave signal propagating in the target direction, including: according to The signal in the wave number domain is returned to the space-time domain through inverse Fourier transform to obtain the space-time fluctuation signal of the internal solitary wave in a specific direction as the target internal solitary wave signal.

9. An internal solitary wave direction decomposition device based on time-space Fourier transform, characterized in that: include: A numerical simulation result acquisition module is used to obtain numerical simulation results of internal solitary waves in the ocean area; A time transform processing module is used to perform time Fourier transform processing according to the parameter time series corresponding to the numerical simulation result to obtain a target frequency domain signal, wherein the target frequency domain signal includes the target positive frequency of the inner solitary wave in each fluctuation component; A spatial transformation processing module is used to perform a two-dimensional spatial Fourier transform processing on the target frequency domain signal to obtain target wave number domain information, wherein the target wave number domain information includes internal wave information in a specific direction; The inverse transform processing module is used to perform inverse Fourier transform according to the target wave number domain information to obtain the target internal solitary wave signal propagating in the target direction.

10. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor is used to implement the steps of the internal solitary wave direction decomposition method based on space-time Fourier transform as described in any one of claims 1 to 8 when executing the program stored in the memory.

Images