Eof reconstruction of sound speed profile based on average sound speed, medium and device

Abstract

The application provides a method, medium and device for reconstructing a sound speed profile based on average sound speed EOF. The method belongs to the field of ocean technology measurement, and first converts temperature and salinity data into sound speed data by using a sound speed empirical formula, and then obtains a standard sound speed layer by using an interpolation function. Secondly, an EOF space function is obtained based on an EOF decomposition method, and then a minimum norm solution of a binary first-order equation set is solved to obtain a reconstruction coefficient. Finally, a sound speed profile is reconstructed by using sample average sound speed, the first three order EOF functions and the EOF reconstruction coefficient. The application uses sound speed at a certain depth and average sound speed from the depth to the sea surface as measured sound speed, and combines sample sound speed to complete the reconstruction of the sound speed profile, which provides a possibility for real-time reconstruction of the sound speed profile at a certain position.

Description

Technical Field

[0001] This invention relates to the field of marine technical measurement, specifically to a method based on average sound speed. Methods, media, and devices for reconstructing sound velocity profiles. Background Technology

[0002] Ocean sound speed profiles can be calculated using empirical sound speed models based on known physical quantities such as temperature, salinity, and depth. Among these, empirical orthogonal functions... The basis function (BF) is the most effective basis function for describing sound velocity profiles in the sense of minimum variance. Previous studies have shown that, when the sound velocity profile changes are not particularly complex, a segment or even a few points with drastic changes in the sound velocity profile can be used to reconstruct the sound velocity profile in shallow seas or even the entire ocean depth. However, this method also has its drawbacks: it can only obtain a portion of the sound velocity values ​​on the sound velocity profile in advance, and then combine them with the sample sound velocity profile to find the least squares solution to the system of equations. The reconstruction coefficients, which are used to reconstruct the sound velocity profile, lack real-time capability and cannot adequately meet certain needs. Summary of the Invention

[0003] In order to The reconstructed sound velocity profile is real-time; this invention provides a method based on average sound velocity. Methods, media, and apparatus for reconstructing sound velocity profiles.

[0004] This invention is achieved through the following technical solution:

[0005] A method based on average sound speed The method for reconstructing the sound velocity profile includes the following specific steps:

[0006] The first step is to obtain historical temperature and salinity data for a specific sea area over a period of time.

[0007] The second step is to adopt... The sound velocity value at the corresponding depth is calculated using an empirical formula for sound velocity; a sample sound velocity matrix is ​​constructed by varying the rows over time and the columns for varying the columns over depth, and then... The interpolation function interpolates the sample sound velocity matrix to a spacing of 1. Depth 1000 Equally spaced standard layers;

[0008] The third step involves performing a row average on the sample sound velocities to obtain the sample average sound velocity. Subtracting the sample sound velocity matrix from the sample average sound velocity matrix yields the perturbation matrix. The covariance matrix of the perturbation matrix is ​​then calculated, and its eigenvalues ​​are decomposed. The decomposed eigenvectors are then arranged in descending order of their eigenvalues. Space functions;

[0009] Fourthly, the sound speed at a certain depth under water and the average sound speed from the depth to the sea surface are taken as the measured sound speed, and the sound speed at the same position is reconstructed by using the first three order function and the average sound speed of the sample at the position. function, and the minimum norm solution of the binary linear equation set is obtained. reconstruction coefficient, the first three order function and the average sound speed of the sample at the position.

[0010] The application also provides a computer readable storage medium, which stores a computer program suitable for being loaded and executed by a processor to perform the method for reconstructing a sound speed profile based on average sound speed. The application further provides a method for reconstructing a sound speed profile based on average sound speed.

[0011] The application further provides a device for reconstructing a sound speed profile based on average sound speed. The device comprises a data processing module, and the data processing module is used to execute the method for reconstructing a sound speed profile based on average sound speed. The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0012] Compared with the prior art, the application has the following beneficial effects:

[0013] The application takes the sound speed at a certain depth under water and the average sound speed from the depth to the sea surface as the measured sound speed, and reconstructs the sound speed at the same position by using the first three order function and the historical average sound speed of the sample. reconstruction coefficient, and the reconstruction of the sound speed profile is completed, and the sound speed profile in the sea area can be obtained in real time. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0015] Figure 2 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0016] Figure 3 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0017] Figure 4 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0018] Figure 5 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0019] Figure 6 The application further provides a device for reconstructing a sound speed profile based on average sound speed.

[0020] Figure 7is the error graph of the reconstructed sound speed profile on September 17, 2020;

[0021] Figure 8 is the comparison graph of the reconstructed sound speed profile and the measured sound speed profile on December 11, 2020;

[0022] Figure 9 is the error graph of the reconstructed sound speed profile on December 11, 2020. DETAILED DESCRIPTION

[0023] The technical solutions of the present application are further explained below by examples, but the protection scope of the present application is not limited in any form by the examples.

[0024] Example 1

[0025] A method for reconstructing a sound speed profile based on average sound speed The method for reconstructing a sound speed profile is shown as follows Figure 1 The specific method is as follows

[0026] Firstly, obtain the temperature and salinity historical data of a sea area for a period of time;

[0027] Secondly, calculate the sound speed value at the corresponding depth by using the sound speed empirical formula; compose a sample sound speed matrix with the time as the row and the depth as the column, and interpolate the sample sound speed matrix into an equal-interval standard layer with an interval of 1 m and a depth of 1000 m by using an interpolation function; Thirdly, obtain the sample average sound speed by performing row average on the sample sound speed, subtract the sample sound speed matrix from the sample average sound speed matrix to obtain a disturbance matrix, calculate the covariance matrix of the disturbance matrix and perform eigenvalue decomposition on the covariance matrix; arrange the decomposed eigenvectors in the order of eigenvalues from large to small to obtain a spatial function;

[0028] Fourthly, take the sound speed at a certain depth under water and the average sound speed from the depth to the sea surface as the measured sound speed, combine the sample average sound speed at the same position and the values corresponding to the first three order functions to solve the minimum norm solution of a binary linear equation system, and obtain the reconstruction coefficient; use the reconstruction coefficient, the first three order functions and the sample average sound speed to reconstruct the sound speed profile at the position.

[0029] The specific application is as follows:

[0030] The specific application is as follows:

[0031] ​​​​We obtained 105 days of temperature and salinity data for a certain sea area, including 15 days before a certain day in 2020, and 15 days before and after that day from 2017 to 2019. These data were used as sample data. The sound velocity profile of the sample was calculated using the empirical formula for sound velocity. The interpolation function interpolates to a spacing of 1. Depth 1000 The equally spaced standard layers are arranged with the row representing time variation and the column representing depth variation to form the sample sound velocity matrix:

[0032]

[0033] The average sample sound velocity matrix is ​​obtained by averaging the sample sound velocity matrix. :

[0034]

[0035] In the formula .

[0036] Subtracting the average sound velocity matrix from the sample sound velocity matrix yields the perturbation matrix:

[0037]

[0038] The covariance matrix of the perturbation matrix can be expressed as:

[0039]

[0040] Eigendecomposition of the covariance matrix yields:

[0041]

[0042] In the formula For the eigenvalue matrix, This is the eigenvector matrix.

[0043] Rearrange the eigenvectors in descending order of their eigenvalues ​​to obtain... Space function, the first The column is the first Step .

[0044] The measured sound speed is taken from the sound speed at a certain depth underwater and the average sound speed from that depth to the sea surface. This is combined with the average sound speed of the sample at that depth and the first three orders of sound speed. The reconstruction coefficients are obtained by finding the minimum norm solution to a system of two linear equations in two variables using a function.

[0045]

[0046] Using sample average sound velocity, Reconstruction coefficients and the first three orders The spatial function can complete the reconstruction of the sound speed profile:

[0047]

[0048] Select 36.75 ,144.85 The temperature and salinity data of the previous 15 days before March 6, 2020, the previous 15 days and the following 15 days before and after March 6, 2017-2019, a total of 105 days, as sample data, based on the above method, the sound speed profile of the location on March 6, 2020 is reconstructed, the reconstruction result is shown in Figure 2 , and the error of the reconstructed sound speed profile is shown in Figure 3 .

[0049] Example 2

[0050] A method for reconstructing a sound speed profile based on the average sound speed Same as example 1, select 36.75 ,144.85 The temperature and salinity data of the previous 15 days before June 24, 2020, the previous 15 days and the following 15 days before and after June 24, 2017-2019, a total of 105 days, as sample data, based on the above method, the sound speed profile of the location on June 24, 2020 is reconstructed, the reconstruction result is shown in Figure 4 , and the error of the reconstructed sound speed profile is shown in Figure 5 .

[0051] Example 3

[0052] A method for reconstructing a sound speed profile based on the average sound speed Same as example 1, select 36.75 ,144.85 The temperature and salinity data of the previous 15 days before September 17, 2020, the previous 15 days and the following 15 days before and after September 17, 2017-2019, a total of 105 days, as sample data, based on the above method, the sound speed profile of the location on September 17, 2020 is reconstructed, the reconstruction result is shown in Figure 6 , and the error of the reconstructed sound speed profile is shown in Figure 7 .

[0053] Example 4

[0054] A method for reconstructing a sound speed profile based on the average sound speed Same as example 1, select 36.75 ,144.85 Temperature and salinity data for 105 days, including the 15 days before December 11, 2020, and the 15 days before and after December 11 from 2017 to 2019, were used as sample data. Based on the method described above, the sound velocity profile at this location on December 11, 2020, was reconstructed. The reconstruction result is as follows: Figure 8 As shown, the error in reconstructing the sound velocity profile is as follows: Figure 9 As shown.

[0055] from Figure 3 , Figure 5 , Figure 7 , Figure 9 It can be seen that the error between the reconstructed sound velocity profile and the measured sound velocity profile is within -3. up to 4 Between these parameters, the real-time performance of reconstructing the sound velocity profile is quite good.

Claims

1. A method based on average sound speed EOF The method for reconstructing the sound velocity profile is characterized by, The specific steps of the method are as follows: The first step is to obtain historical temperature and salinity data for a specific sea area over a period of time. The second step is to adopt... Chen-Millero The sound velocity value at the corresponding depth is calculated using an empirical formula for sound velocity; a sample sound velocity matrix is ​​constructed by varying the rows over time and the columns for varying the columns over depth, and then... Akima The interpolation function interpolates the sample sound velocity matrix into equidistant standard layers with a spacing of 1m and a depth of 1000m; The third step involves performing a row average on the sample sound velocities to obtain the sample average sound velocity. Subtracting the sample sound velocity matrix from the sample average sound velocity matrix yields the perturbation matrix. The covariance matrix of the perturbation matrix is ​​then calculated, and its eigenvalues ​​are decomposed. The decomposed eigenvectors are then arranged in descending order of their eigenvalues. EOF Space functions; The fourth step involves taking the sound speed at a certain depth underwater and the average sound speed from that depth to the sea surface as the measured sound speed, combining this with the average sound speed of samples from the same location and the first three orders of sound velocity. EOF Find the minimum norm solution of the system of three linear equations with the corresponding function value. EOF Reconstruction coefficients; Using sample average sound velocity, EOF Reconstruction coefficients and the first three orders EOF The spatial function can be used to reconstruct the sound velocity profile.

2. A computer-readable storage medium storing a computer program adapted to be loaded by a processor and executed by means of claim 1 based on average speed of sound. EOF A method for reconstructing the sound velocity profile.

3. A method based on average sound speed EOF An apparatus for reconstructing a sound velocity profile, the apparatus comprising a data processing module, the data processing module performing the operation described in claim 1 based on average sound velocity. EOF A method for reconstructing the sound velocity profile.

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