A method and system for obtaining vertical distribution of ocean suspended particle concentration

Abstract

The present invention provides a method and system for obtaining the vertical distribution of marine suspended particulate matter concentration, matching the TSM concentration data with the in-situ measurement data of various bio-optical parameters at the same depth, and then respectively performing correlation analysis between the TSM concentration and the various bio-optical parameters, setting the determination coefficient threshold to screen the bio-optical parameters highly correlated with the TSM concentration, determining the optimal bio-optical parameters by stepwise regression, obtaining the TSM concentration fitting relationship expressed by the optimal bio-optical parameters, and calculating the corresponding TSM concentration vertical distribution data using the in-situ measurement data of the bio-optical parameters. The present invention comprehensively considers a variety of bio-optical parameters and has a reliable theoretical basis. At the same time, the on-site in-situ measurement instrument can quickly measure high-resolution vertical distribution data, so that the resolution of the obtained TSM concentration vertical distribution data is greatly improved, which helps to more objectively and accurately reflect the distribution change characteristics of the TSM vertical distribution.

Description

Technical Field

[0001] The present invention relates to the field of ocean remote sensing technology, and in particular to a method and system for obtaining vertical distribution of ocean suspended particle concentration. Background Art

[0002] Total Suspended Matter (TSM) is a general term for all suspended matter in seawater, mainly including phytoplankton, suspended sediment, plant and animal debris, and floccules. Suspended particulate matter is not only the main source of sediment in nearshore estuary areas, directly affecting the exchange and deposition of substances, and has an important impact on shipping and the marine environment, but also significantly affects the vertical distribution of light and temperature fields, thereby affecting the composition and primary production process of phytoplankton, and further affecting the process of carbon cycle. Therefore, revealing the vertical distribution change information of TSM concentration has important scientific value and practical application significance for multiple research fields such as marine sedimentation process, marine material transport, and carbon cycle.

[0003] The traditional method of obtaining TSM concentration is field voyage sampling, indoor filtration, drying, and weighing, that is, obtaining it through sampling and calculation. Researchers obtain laboratory analysis data of TSM concentration by conducting field survey voyages to study its vertical distribution changes. However, during field voyage surveys, only water samples from a few discrete water layers can be collected, resulting in the measured TSM data concentration being very limited in the vertical profile. Researchers need to use mathematical interpolation methods based on TSM data from a limited number of discrete water layers to obtain the vertical distribution characteristics of TSM. However, the TSM vertical distribution information obtained by this interpolation is difficult to accurately and objectively characterize its distribution characteristics, and even makes incorrect estimates of the vertical distribution characteristics.

[0004] Since TSM has a strong absorption and scattering effect on light entering the water body, TSM has a significant impact on the inherent optical properties (IOPs) of the water body. Different TSM vertical distribution types will cause significant changes in optical parameters, which makes the changes in optical parameters implicit in the information of the vertical distribution type of TSM. Many studies have shown that optical parameters such as the absorption coefficient ap(λ), backscattering coefficient bbp(λ), and beam attenuation coefficient cp(λ) of particulate matter have a good correlation with TSM. These related studies have shown that researchers can obtain TSM concentration information by measuring optical parameters.

[0005] For water bio-optical parameters, such as particle backscattering coefficient, beam attenuation coefficient, particle number concentration, water turbidity, etc., there are currently on-site in-situ measurement instruments that can quickly measure and obtain vertical high-resolution distribution data of these parameters. However, there is still a lack of methods for comprehensively utilizing multiple bio-optical parameters to obtain vertical high-resolution distribution of TSM concentration. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a method and system for obtaining the vertical distribution of marine suspended particle concentration using in-situ measurement data of bio-optical parameters with high resolution and high reliability.

[0007] Technical solution: A method for obtaining the vertical distribution of suspended particle concentration in the ocean, comprising the following steps:

[0008] (1) Collect in situ measurement data of bio-optical parameters and laboratory analysis data of TSM concentration from several cruises in the study area, and match the laboratory analysis data of TSM concentration with the in situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching data set;

[0009] (2) Based on the TSM concentration-bio-optical parameter matching data set, the correlation between TSM concentration and various bio-optical parameters was quantitatively analyzed to obtain the determination coefficient between TSM concentration and various bio-optical parameters. The bio-optical parameters with a determination coefficient greater than the set threshold were screened out to form a bio-optical parameter data set.

[0010] (3) Based on the bio-optical parameter data set, the optimal bio-optical parameters were determined using the stepwise regression method, and the fitting relationship between the optimal bio-optical parameters and TSM concentration was obtained;

[0011] (4) The fitting relationship between the optimal bio-optical parameters and TSM concentration was used to process the in situ measurement data of the vertical distribution of bio-optical parameters in the study area to obtain the corresponding vertical distribution data of TSM concentration.

[0012] Specifically, the in situ measurement data of bio-optical parameters include particle backscattering coefficient, beam attenuation coefficient, particle number concentration, particle size distribution, absorption coefficient, water turbidity, chlorophyll a concentration, and colored soluble organic matter concentration.

[0013] Specifically, in step (2), the correlation quantitative analysis includes: calculating the determination coefficients of TSM concentration and various bio-optical parameters under linear and logarithmic fitting methods, respectively, and selecting the fitting method with a larger determination coefficient, and comparing the determination coefficient obtained under the fitting method with a set threshold; preferably, the set threshold is greater than or equal to 0.70.

[0014] Specifically, in step (3), the fitting relationship between the optimal bio-optical parameters and TSM concentration is:

[0015]

[0016] Where: TSM is TSM concentration, a i is the fitting coefficient, i =0, 1, 2, …, n; x j is the bio-optical parameter, j =1, 2, 3, …, n; f is the fitting relationship between TSM concentration and bio-optical parameters, which is a linear relationship or a logarithmic relationship.

[0017] Preferably, step (4) further comprises:

[0018] The vertical distribution data of TSM concentration were dimensionlessly processed to calculate the relative water depth and normalized TSM concentration. The calculation formula is:

[0019] ;

[0020]

[0021] Where: h r is the relative water depth, z is the water depth at the measuring point, h is the total water depth, TSM * ( h r ) is the normalized TSM concentration, TSM( h r ) is the relative water depth h r TSM concentration value at surf is the surface TSM concentration;

[0022] The dimensionless vertical distribution data of TSM concentration were analyzed using the visual interpretation method, and the types of vertical distribution of TSM concentration in the study area were divided.

[0023] Preferably, the method for obtaining the vertical distribution of the concentration of suspended particulate matter in the ocean further comprises the following steps:

[0024] The TSM concentration laboratory analysis data is used to perform an accuracy test on the fitting relationship between the optimal bio-optical parameter and the TSM concentration in step (3). If the accuracy test result meets the set requirements, proceed to step (4). If the accuracy test result does not meet the set requirements, increase the set threshold of the determination coefficient between the TSM concentration and various bio-optical parameters in step (2) until the set requirements for the accuracy test are met.

[0025] Specifically, the above-mentioned precision test includes: inputting the bio-optical parameter data set into the fitting relationship between the optimal bio-optical parameter and the TSM concentration to obtain the TSM concentration calculation value, and performing consistency analysis on the TSM concentration calculation value and the TSM concentration laboratory analysis data corresponding to the bio-optical parameter data set to obtain the determination coefficient, the mean absolute relative error and the root mean square error.

[0026] Preferably, in step (3), the bio-optical parameter data set is randomly divided into a training set and a validation set according to a set ratio, the training set is used for stepwise regression training, and the validation set is used for accuracy testing.

[0027] The present invention also provides a system for obtaining the vertical distribution of the concentration of suspended particles in the ocean, comprising:

[0028] Dataset construction module: used to collect in-situ measurement data of bio-optical parameters and laboratory analysis data of TSM concentration from several voyages in the study area, and match the laboratory analysis data of TSM concentration with the in-situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching dataset;

[0029] Bio-optical parameter screening module: used to perform quantitative correlation analysis between TSM concentration and various bio-optical parameters based on the TSM concentration-bio-optical parameter matching data set, obtain the determination coefficient between TSM concentration and various bio-optical parameters, and screen out bio-optical parameters with a determination coefficient greater than a set threshold to form a bio-optical parameter data set;

[0030] Parameter fitting module: used to determine the optimal bio-optical parameters based on the bio-optical parameter data set using the stepwise regression method, and obtain the fitting relationship between the optimal bio-optical parameters and TSM concentration;

[0031] TSM concentration vertical distribution output module: used to process the in-situ measurement data of the vertically distributed bio-optical parameters in the study area using the fitting relationship between the optimal bio-optical parameters and TSM concentration, and obtain the corresponding TSM concentration vertical distribution data.

[0032] Beneficial effects: Compared with the prior art, the present invention has the following significant effects:

[0033] (1) The present invention provides a new method for obtaining TSM concentration by fitting bio-optical parameters. First, the TSM concentration data with consistent measurement depth are matched with the in situ measurement data of various bio-optical parameters. Then, the correlation between TSM concentration and various bio-optical parameters is analyzed respectively. The bio-optical parameters with high correlation with TSM concentration are screened by setting the determination coefficient threshold. Then, the optimal combination of bio-optical parameters is determined by the stepwise regression method. The TSM concentration fitting relationship expressed by the optimal bio-optical parameters is obtained. The method comprehensively considers multiple bio-optical parameters and has a reliable optical theoretical basis.

[0034] (2) Since the on-site in-situ measurement instruments can measure nearly continuous (vertical resolution can reach 0.1-0.2 m) vertical distribution data, the TSM concentration fitting equation obtained by this method can obtain nearly continuous TSM concentration vertical distribution data, which greatly improves the resolution of TSM concentration vertical distribution and is conducive to more objectively and accurately reflecting the distribution change characteristics of TSM vertical distribution.

[0035] (3) The on-site in-situ measurement instrument can quickly measure the bio-optical parameter data and is easy to operate. Compared with the direct measurement of TSM concentration, it greatly improves the ability and efficiency of obtaining TSM concentration data, making it easier to obtain a large amount of TSM concentration vertical distribution data and conduct related research. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of the method of embodiment 1 of the present invention.

[0037] Figure 2 This is a schematic diagram of the correlation analysis between TSM concentration and bio-optical parameters in Example 2 of the present invention Figure 1 .

[0038] Figure 3 This is a schematic diagram of the correlation analysis between TSM concentration and bio-optical parameters in Example 2 of the present invention Figure 2 .

[0039] Figure 4 This is a schematic diagram of the correlation analysis between TSM concentration and bio-optical parameters in Example 2 of the present invention Figure 3 .

[0040] Figure 5 It is a scatter plot of TSM concentration calculation data and TSM concentration measured data in Example 2 of the present invention.

[0041] Figure 6 It is a dimensionless TSM concentration vertical distribution curve and type schematic diagram of Example 2 of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings. Example 1

[0043] See also Figure 1 As shown, this embodiment provides a method for obtaining the vertical distribution of suspended particle concentration in the ocean, comprising the following steps:

[0044] (1) Collect in situ measurement data of bio-optical parameters from several voyages in the study area, including profile data of bio-optical parameters such as particle backscattering coefficient, beam attenuation coefficient, particle number concentration, particle size distribution, absorption coefficient, and water turbidity. Obtain laboratory analysis data of TSM concentration in the surface, middle, and bottom layers of the water body. Match the TSM concentration laboratory analysis data with the in situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching data set.

[0045] (2) Based on the TSM concentration-bio-optical parameter matching data set, the correlation between TSM concentration and various bio-optical parameters was quantitatively analyzed. The determination coefficients of TSM concentration and various bio-optical parameters under linear and logarithmic fitting methods were calculated respectively. The fitting method with a larger determination coefficient was selected, and the determination coefficient obtained under this fitting method was compared with the set threshold. The bio-optical parameters with a determination coefficient greater than the set threshold were screened out to form a bio-optical parameter data set.

[0046] (3) Based on the bio-optical parameter data set, the optimal bio-optical parameters are determined using the stepwise regression method. In this step, the bio-optical parameter data set is randomly divided into a training set and a validation set according to a set ratio. The training set is used for stepwise regression training, and the validation set is used for subsequent accuracy testing of the fitting relationship. Stepwise regression is a commonly used statistical method for variable screening. Its purpose is to select the optimal combination of variables from multiple independent variables to establish an efficient regression model; by gradually introducing or eliminating variables, evaluating the contribution of each variable to the model, and finally retaining the independent variables that have a significant impact on the dependent variable, thereby improving the explanatory power and predictive ability of the model. Using the stepwise regression method, the fitting relationship between the optimal bio-optical parameters and TSM concentration is obtained as follows:

[0047]

[0048] Where: TSM is TSM concentration, a i is the fitting coefficient, i =0, 1, 2, …, n; x j is the bio-optical parameter, j =1, 2, 3, …, n; f is the fitting relationship between TSM concentration and bio-optical parameters, which is a linear relationship or a logarithmic relationship.

[0049] (4) Using the TSM concentration laboratory analysis data, perform precision test on the fitting relationship between the optimal bio-optical parameter and TSM concentration in step (3). If the precision test result meets the set requirements, proceed to step (4). If the precision test result does not meet the set requirements, increase the set threshold of the determination coefficient between TSM concentration and various bio-optical parameters in step (2) until the set requirements of the precision test are met.

[0050] The precision test includes: inputting the bio-optical parameter data set into the fitting relationship between the optimal bio-optical parameters and TSM concentration to obtain the calculated TSM concentration value, performing consistency analysis on the calculated TSM concentration value and the TSM concentration laboratory analysis data corresponding to the bio-optical parameter data set, obtaining the determination coefficient, mean absolute relative error and root mean square error, and comparing them with the corresponding set requirements.

[0051] (5) The in-situ measurement data of the vertical distribution of bio-optical parameters in the study area were processed using the fitting relationship between the optimal bio-optical parameters and TSM concentration to obtain the corresponding high-resolution vertical distribution data of TSM concentration. The vertical distribution data of TSM concentration were dimensionlessly processed to calculate the relative water depth and normalized TSM concentration. The calculation formula is:

[0052] ;

[0053]

[0054] Where: h r is the relative water depth, z is the water depth at the measuring point, h is the total water depth, TSM * ( h r ) is the normalized TSM concentration, TSM( h r ) is the relative water depth h r TSM concentration value at surf is the surface TSM concentration;

[0055] The dimensionless vertical distribution data of TSM concentration were analyzed using the visual interpretation method, and the types of vertical distribution of TSM concentration in the study area were divided. Example 2

[0056] This embodiment provides a specific implementation case of the method for obtaining the vertical distribution of the concentration of suspended particulate matter in the ocean recorded in Embodiment 1, including the following steps:

[0057] (1) In this example, measured data from multiple voyages in a certain sea area in different seasons from 2016 to 2018 were collected, including 569 TSM concentration data of the surface, middle and bottom layers of water bodies obtained by laboratory measurement and analysis at 223 stations, and high-resolution vertical distribution in-situ measurement data of bio-optical parameters at 223 stations (resolution of 0.1-0.2 m), including but not limited to: particle size D measured by LISST-100X laser particle size analyzer A , particle number concentration N0 and beam attenuation coefficient c p , water turbidity Turb, chlorophyll a concentration Chla and colored soluble organic matter concentration CDOM measured by ECO multi-parameter instrument, backscatter coefficient b of multiple wavelengths measured by HS-6 backscatter instrument bp According to the measured depths of TSM concentration data in the surface, middle and bottom layers of the water body, the bio-optical parameter data at the corresponding depths were matched to construct a TSM concentration-bio-optical parameter matching dataset.

[0058] (2) Based on the TSM concentration-bio-optical parameter matching dataset constructed in step (1), the TSM concentration and the suspended particle size D A , particle number concentration N0, water turbidity Turb, beam attenuation coefficient c p , backscattering coefficient b at multiple wavelengths bp The correlation between TSM concentration and various bio-optical parameters in linear and logarithmic conditions was calculated. 2 In this embodiment, it is found through calculation that in the logarithmic case, the determination coefficient between the TSM concentration and various bio-optical parameters is larger. According to the calculated determination coefficient, in this embodiment, 0.70 is used as the threshold value to screen out the bio-optical parameters with a determination coefficient greater than or equal to 0.70 with the TSM concentration to form a bio-optical parameter data set.

[0059] See also Figures 2 to 4 , which is a schematic diagram of the correlation analysis between TSM concentration and some bio-optical parameters in this embodiment, Figures 2 to 4 The coordinates are all logarithmic. Figure 2 Neutron graph (a) shows the relationship between TSM concentration and suspended particle size D A Schematic diagram of correlation analysis. Figure 2 Neutron diagram (b) is a schematic diagram of the correlation analysis between TSM concentration and particle number concentration N0. Figure 2 Neutron figure (c) is a schematic diagram of the correlation analysis between TSM concentration and water turbidity Turb. Figure 2 Neutron figure (d) is a schematic diagram of the correlation analysis between TSM concentration and chlorophyll a concentration Chla; Figure 3The neutron graph (e) is a schematic diagram of the correlation analysis between TSM concentration and colored soluble organic matter concentration CDOM. Figure 3 Neutron image (f) shows the TSM concentration and the particle backscattering coefficient b at 442 nm. bp (442) Schematic diagram of correlation analysis, Figure 3 Neutron image (g) shows the TSM concentration and the particle backscattering coefficient b at 488 nm. bp (488) Schematic diagram of correlation analysis, Figure 3 Neutron image (h) shows the TSM concentration and the particle backscattering coefficient b at 550nm. bp (550) Schematic diagram of correlation analysis; Figure 4 Neutron image (i) shows the TSM concentration and the particle backscattering coefficient b at 620 nm. bp (620) Schematic diagram of correlation analysis, Figure 4 Neutron image (j) shows the TSM concentration and the particle backscattering coefficient b at 700 nm. bp (700) Schematic diagram of correlation analysis, Figure 4 Neutron image (k) shows the TSM concentration and the particle backscattering coefficient b at 852nm. bp (852) Schematic diagram of correlation analysis, Figure 4 Neutron graph (l) shows the relationship between TSM concentration and beam attenuation coefficient c at 670 nm. p (670) Schematic diagram of correlation analysis. Among the 12 bio-optical parameters, 10 bio-optical parameters meet the determination coefficient R 2 The threshold condition was greater than or equal to 0.70, and the bio-optical parameters with a greater correlation with TSM concentration were preliminarily screened out in the original data through correlation analysis.

[0060] (3) Based on the bio-optical parameter data set obtained by screening in step (2), the optimal bio-optical parameter for estimating the TSM concentration is determined by the stepwise regression method. In this embodiment, the bio-optical parameter data set is randomly divided into a training set and a validation set at a ratio of 7:3 to ensure the independence of the training set and the validation set during the model establishment process. Through the correlation analysis in step (2), it is found that the correlation between TSM concentration and various bio-optical parameters is better in the logarithmic coordinate system. Therefore, after taking the logarithm of TSM concentration and various bio-optical parameters, the quantitative relationship is determined by the stepwise regression method, and then the fitting relationship is obtained:

[0061]

[0062] Where: TSM is TSM concentration, a i is the fitting coefficient, i =0, 1, 2, …, n; x jis the bio-optical parameter, j =1, 2, 3, …, n; log is a logarithmic function.

[0063] Through the stepwise regression method, in this embodiment, the suspended particle size D is finally selected. A , particle number concentration N0, water turbidity Turb, particle backscattering coefficient b at 442nm bp (442), particle backscattering coefficient b at 488nm bp (488), particle backscattering coefficient b at 550nm bp Backscattering coefficient of particles at (550) and 620nm b bp (620), particle backscattering coefficient b at 700nm bp (700), 852nm particle backscattering coefficient b bp (852) and 670nm beam attenuation coefficient c p (670) was used as the optimal bio-optical parameter for estimating TSM concentration. On this basis, a new method for estimating the vertical distribution of TSM concentration was established using the fitting relationship. The determined model parameters and corresponding coefficients are shown in Table 1.

[0064] Table 1 Fitting coefficient table

[0065]

[0066] (4) Using the fitted relationship between the optimal bio-optical parameters and TSM concentration obtained in step (3), and taking the bio-optical parameter data in the validation set as input, the TSM concentration calculation data at different water depths (surface, middle and bottom layers) were obtained, and the accuracy was tested using the corresponding TSM concentration measured data. Figure 5 As shown, by analyzing the scatter plot, the determination coefficient R is calculated. 2 =0.90, mean absolute relative error MAPE = 26.21% and root mean square error RMSE = 8.013 mg·L -1 , all meet the accuracy requirements of the present invention. Through the above accuracy test, it is determined that the present method has good accuracy and stability.

[0067] (5) The fitting relationship between the optimal bio-optical parameters and TSM concentration is used as the calculation formula for TSM concentration estimation. It is applied to the vertical continuous measurement data of bio-optical parameters measured in situ, so as to obtain high-resolution vertical distribution data of TSM concentration in the study area conveniently and quickly. The vertical distribution data of TSM concentration is dimensionlessly processed, and the relative water depth and the corresponding normalized TSM concentration are calculated. The formula is as follows:

[0068] ;

[0069]

[0070] Where: h r is the relative water depth, z is the water depth at the measuring point, h is the total water depth, that is, the relative water depth of the sea surface layer is 1, the relative water depth of the bottom layer is 0, and the relative water depth of the middle layer is 0.5; TSM * ( h r ) is the normalized TSM concentration, TSM( h r ) is the relative water depth h r TSM concentration value at surf is the surface TSM concentration.

[0071] See also Figure 6 As shown in Figure 2, after obtaining the normalized TSM concentration, a dimensionless TSM concentration vertical distribution curve is established. Using the visual interpretation method, according to the rate of increase of TSM concentration on the profile, the dimensionless TSM concentration vertical distribution curve obtained in the sea area can be divided into uniform type (such as Figure 6 Neutron graph (a)) or incremental type (such as Figure 6 Neutron image (b)), further analysis of the dimensionless TSM concentration vertical distribution curve can obtain the spatial and temporal variation characteristics of the vertical distribution of TSM concentration in the sea area. Example 3

[0072] This embodiment provides a system for obtaining the vertical distribution of the concentration of suspended particles in the ocean, corresponding to the method for obtaining the vertical distribution of the concentration of suspended particles in the ocean recorded in Embodiment 1, including the following modules:

[0073] Dataset construction module: used to collect in-situ measurement data of bio-optical parameters and laboratory analysis data of TSM concentration from several voyages in the study area, and match the laboratory analysis data of TSM concentration with the in-situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching dataset;

[0074] Bio-optical parameter screening module: used to perform quantitative correlation analysis between TSM concentration and various bio-optical parameters based on the TSM concentration-bio-optical parameter matching data set, obtain the determination coefficient between TSM concentration and various bio-optical parameters, and screen out bio-optical parameters with a determination coefficient greater than a set threshold to form a bio-optical parameter data set;

[0075] Parameter fitting module: used to determine the optimal bio-optical parameters based on the bio-optical parameter data set using the stepwise regression method, and obtain the fitting relationship between the optimal bio-optical parameters and TSM concentration;

[0076] TSM concentration vertical distribution output module: used to process the in-situ measurement data of the vertically distributed bio-optical parameters in the study area using the fitting relationship between the optimal bio-optical parameters and TSM concentration, and obtain the corresponding TSM concentration vertical distribution data.

Claims

1. A method for obtaining the vertical distribution of suspended particulate matter concentration in the ocean, characterized in that: The following steps are involved: (1) Collect in situ measurement data of bio-optical parameters and laboratory analysis data of TSM concentration from several voyages in the study area, and match the laboratory analysis data of TSM concentration with the in situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching data set; the bio-optical parameters include particle backscattering coefficient, beam attenuation coefficient, particle number concentration, particle size distribution, absorption coefficient, water turbidity, chlorophyll a concentration, and colored soluble organic matter concentration; (2) Based on the TSM concentration-bio-optical parameter matching data set, the correlation between TSM concentration and various bio-optical parameters was quantitatively analyzed, and the determination coefficients of TSM concentration and various bio-optical parameters under linear and logarithmic fitting methods were calculated respectively. The fitting method with a larger determination coefficient was selected, and the determination coefficient obtained under the fitting method was compared with the set threshold. The bio-optical parameters with a determination coefficient greater than the set threshold were screened out to form a bio-optical parameter data set; (3) Based on the bio-optical parameter data set, the optimal bio-optical parameters were determined using the stepwise regression method, and the fitting relationship between the optimal bio-optical parameters and TSM concentration was obtained; (4) The fitting relationship between the optimal bio-optical parameters and TSM concentration was used to process the in situ measurement data of the vertical distribution of bio-optical parameters in the study area to obtain the corresponding vertical distribution data of TSM concentration.

2. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 1, characterized in that: In the step (2), the threshold is set to be greater than or equal to 0.

70.

3. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 1, characterized in that: In step (3), the fitting relationship between the optimal bio-optical parameters and TSM concentration is: f(TSM)=a0+a1·f(x1)+a2·f(x2)+…+a n ·f(x n ) Where: TSM is TSM concentration, a i is the fitting coefficient, i = 0, 1, 2, ..., n; x j is the bio-optical parameter, j = 1, 2, 3, ..., n; f is the fitting relationship between TSM concentration and the bio-optical parameter, which is a linear relationship or a logarithmic relationship.

4. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 1, characterized in that: The step (4) further comprises: The vertical distribution data of TSM concentration were dimensionlessly processed to calculate the relative water depth and normalized TSM concentration. The calculation formula is: h r =1-z / h TLV * (h r )=TSM(h r ) / TSM surf Where: h r is the relative water depth, z is the water depth at the measuring point, h is the total water depth, TSM * (h r ) is the normalized TSM concentration, TSM (h r ) is the relative water depth h r TSM concentration value at surf is the surface TSM concentration; The dimensionless vertical distribution data of TSM concentration were analyzed using the visual interpretation method, and the types of vertical distribution of TSM concentration in the study area were divided.

5. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 1, characterized in that: The method for obtaining the vertical distribution of the concentration of suspended particles in the ocean also includes the following steps: The TSM concentration laboratory analysis data is used to perform an accuracy test on the fitting relationship between the optimal bio-optical parameters and the TSM concentration in step (3). If the accuracy test result meets the set requirements, proceed to step (4). If the accuracy test result does not meet the set requirements, increase the set threshold of the determination coefficient between the TSM concentration and various bio-optical parameters in step (2) until the set requirements for the accuracy test are met.

6. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 5, characterized in that: The precision test includes: inputting the bio-optical parameter data set into the fitting relationship between the optimal bio-optical parameter and the TSM concentration to obtain the TSM concentration calculation value, and performing consistency analysis on the TSM concentration calculation value and the TSM concentration laboratory analysis data corresponding to the bio-optical parameter data set to obtain the determination coefficient, the average absolute relative error and the root mean square error.

7. The method for obtaining vertical distribution of suspended particle concentration in the ocean according to claim 5, characterized in that: In the step (3), the bio-optical parameter data set is randomly divided into a training set and a validation set according to a set ratio, the training set is used for stepwise regression training, and the validation set is used for accuracy testing.

8. A system for obtaining vertical distribution of suspended particle concentration in the ocean, characterized in that: include: Dataset construction module: used to collect in-situ measurement data of bio-optical parameters and laboratory analysis data of TSM concentration from several voyages in the study area, and match the TSM concentration laboratory analysis data with the in-situ measurement data of bio-optical parameters at the corresponding depth according to the measurement depth to construct a TSM concentration-bio-optical parameter matching dataset; the bio-optical parameters include particle backscattering coefficient, beam attenuation coefficient, particle number concentration, particle size distribution, absorption coefficient, water turbidity, chlorophyll a concentration, and colored soluble organic matter concentration; Bio-optical parameter screening module: used to perform quantitative correlation analysis between TSM concentration and various bio-optical parameters based on the TSM concentration-bio-optical parameter matching data set, calculate the determination coefficients of TSM concentration and various bio-optical parameters under linear and logarithmic fitting methods, select the fitting method with a larger determination coefficient, compare the determination coefficient obtained under the fitting method with the set threshold, screen out the bio-optical parameters with a determination coefficient greater than the set threshold, and form a bio-optical parameter data set; Parameter fitting module: used to determine the optimal bio-optical parameters based on the bio-optical parameter data set using the stepwise regression method, and obtain the fitting relationship between the optimal bio-optical parameters and TSM concentration; TSM concentration vertical distribution output module: used to process the in-situ measurement data of the vertically distributed bio-optical parameters in the study area using the fitting relationship between the optimal bio-optical parameters and TSM concentration, and obtain the corresponding TSM concentration vertical distribution data.

Images