GNSS-R ocean plumb line deviation calculation method, device and equipment and storage medium

Abstract

The invention relates to the technical field of satellite height measurement, and discloses a GNSS-R ocean plumb line deviation calculation method, device and equipment and a storage medium. The method comprises the following steps: acquiring a height measurement result, a geoid height and an average dynamic terrain of each GNSS-R mirror reflection point in an ocean area, and calculating a residual geoid height; dividing a global geographic area according to a longitude and latitude target interval to generate a target grid; for any lattice point in the target grid, screening a plurality of GNSS-R mirror reflection points around the lattice point as target points; and determining the weight of the residual geoid height of each target point based on the GNSS-R height measurement precision table, calculating the residual geoid height of the network point through weighted average, and further calculating the corresponding ocean plumb line deviation. By adopting the method, the global ocean plumb line deviation can be quickly calculated based on the GNSS-R sea surface height measurement result, and the accuracy of ocean plumb line deviation calculation is improved.

Description

Technical Field

[0001] The present application relates to the field of satellite altimetry technology, and in particular to a GNSS-R ocean vertical deviation calculation method, device, equipment and storage medium. Background Art

[0002] Vertical deviation is the basic data for many applications such as the inversion of the earth's gravity field, calculation of elevation anomalies, and precision engineering surveying. It is very important to accurately determine the vertical deviation. Traditional ship-based and airborne gravity field measurement methods have limited capabilities in large-scale global measurements. Gravity measurement satellites have greatly promoted the development of this field by providing high-precision gravity data around the world every month. However, they mainly capture medium- and long-wave information of the gravity field (about 300 kilometers) and are not very sensitive to short-wave signals. Satellite altimetry technology contains valuable high-frequency information about the earth's gravity field. Inverting ocean vertical deviations and gravity anomalies from satellite radar altimetry significantly improves the accuracy and spatial resolution of ocean gravity field inversion. However, satellite altimetry technology is costly, and it is still a problem to form a large-scale constellation network for high-efficiency detection.

[0003] In recent years, the emerging GNSS-R interferometric altimetry technology has provided a new short-wave gravity field measurement technology. The observation satellite can simultaneously receive multiple GNSS signals from multiple signal sources without transmitting signals. Therefore, this method has the advantages of wide coverage, low cost, easy networking, and is conducive to rapid global coverage and revisits.

[0004] However, the height measurement accuracy of the sea surface height data products generated by GNSS-R interferometric height measurement technology is closely related to multiple factors such as the satellite incidence angle, the type of signal source navigation system, and the effective wave height of the sea surface. In addition, the observation trajectory of the sea surface height data product is closely related to the visible duration of the navigation satellite. Since the observation trajectory cannot be continuous for a long time, it is difficult to accurately calculate the global ocean vertical deviation. Based on this, how to achieve accurate calculation of the global ocean vertical deviation based on the satellite-borne GNSS-R sea surface height measurement results is a problem that needs to be solved at present. Summary of the invention

[0005] In view of this, the present application aims to propose a GNSS-R ocean vertical deviation calculation method to achieve accurate calculation of the global ocean vertical deviation based on the satellite-borne GNSS-R sea surface altimetry results.

[0006] To achieve the above purpose, the technical solution of this application is as follows:

[0007] A first aspect of an embodiment of the present application provides a GNSS-R ocean vertical deviation calculation method, the method comprising:

[0008] Obtain the altimetry results, geoid height and average dynamic topography of each GNSS-R mirror reflection point in the ocean area, and calculate the residual geoid height of each GNSS-R mirror reflection point;

[0009] Divide the global geographical area according to the target interval of longitude and latitude to generate the target grid;

[0010] For any grid point in the target grid, multiple GNSS-R specular reflection points around the grid point are selected as the target point;

[0011] Determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; the GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incident angles and sea surface effective wave height conditions;

[0012] Based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated.

[0013] Optionally, obtaining height measurement results of multiple GNSS-R mirror reflection points measured by an observation satellite in an ocean area based on GNSS signals includes:

[0014] Acquire a sea surface height data product measured by GNSS-R; the sea surface height data product includes: the height measurement results of all GNSS-R specular reflection points measured globally by the observation satellite based on GNSS signals; each height measurement result has a corresponding incident angle;

[0015] Based on a first threshold, removing sea surface height measurement results having an incident angle greater than the first threshold from the sea surface height data product;

[0016] Based on the actual observation area of ​​each GNSS-R mirror reflection point, the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface are eliminated from the sea surface height data product; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as the side lengths.

[0017] Optionally, the residual geoid height of each GNSS-R specular reflection point is calculated, including:

[0018] Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0019] Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0020] Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

[0021] Optionally, screening a plurality of GNSS-R specular reflection points around the network point as target points includes:

[0022] Based on the target spatial range, all GNSS-R specular reflection points around the network point that do not exceed the target spatial range are screened out as target points; the target spatial range is an area enclosed by a side length whose longitude and latitude from the network point is not less than half of the target interval.

[0023] Optionally, after selecting all GNSS-R mirror reflection points around the network point that do not exceed the target space range as target points, the method further includes:

[0024] Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

[0025] Optionally, before determining the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, the method further includes:

[0026] Collecting statistics on the altitude measurement accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by the observation satellite based on the GNSS signals transmitted by different types of signal sources on a global scale;

[0027] For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

[0028] Optionally, the weight of the residual geoid height of each target point is determined based on the GNSS-R height measurement accuracy table, and the residual geoid height of the network point is calculated by weighted average, including:

[0029] Obtain the incident angle and effective wave height of the sea surface corresponding to the height measurement results of each target point;

[0030] Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy;

[0031] Determine the weight of the corresponding residual geoid height based on each height measurement accuracy;

[0032] Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

[0033] Optionally, based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated, including:

[0034] Calculating residual vertical deviation based on residual geoid height of the grid point;

[0035] According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation;

[0036] Calculating the model vertical deviation based on the geoid height of the grid point;

[0037] The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

[0038] Optionally, after calculating the average residual geoid height of the network points, the method further comprises:

[0039] When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval;

[0040] determining a sparsity factor based on the new target interval;

[0041] Based on the sparse multiple, a new target grid is generated on the basis of the old target grid;

[0042] Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting;

[0043] Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

[0044] Optionally, the target interval is greater than the maximum value of the cross-track spatial resolution and the along-track spatial resolution corresponding to the height measurement results of each GNSS-R mirror reflection point.

[0045] According to a second aspect of an embodiment of the present application, a GNSS-R ocean vertical deviation calculation device is provided, the device comprising:

[0046] The preprocessing module is configured to obtain the altimetry results, geoid height and average dynamic terrain of each GNSS-R mirror reflection point in the ocean area based on GNSS-R, and calculate the residual geoid height of each GNSS-R mirror reflection point;

[0047] A grid generation module is configured to divide the global geographic area according to target intervals of longitude and latitude to generate a target grid;

[0048] A grid screening module is configured to screen, for any grid point in the target grid, a plurality of GNSS-R specular reflection points around the grid point as a target point;

[0049] The calculation module is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; the GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incident angles and sea surface effective wave height conditions; based on the residual geoid height and geoid height of each network point, calculate the corresponding ocean vertical deviation.

[0050] Optionally, the preprocessing module includes:

[0051] The acquisition submodule is configured to obtain sea surface height data products of GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points measured globally by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle;

[0052] The first screening submodule is configured to, based on a first threshold, eliminate from the sea surface height data product the sea surface height measurement results whose incident angles are greater than the first threshold; based on the actual observation area of ​​each GNSS-R mirror reflection point, eliminate from the sea surface height data product the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as side lengths.

[0053] Optionally, the preprocessing module further includes a first calculation submodule configured to perform the following steps:

[0054] Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0055] Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0056] Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

[0057] Optionally, the grid screening module is specifically configured to screen out all GNSS-R mirror reflection points around the grid point that do not exceed the target spatial range as target points based on the target spatial range; the target spatial range is an area enclosed by a side length whose longitude and latitude from the grid point is not less than half of the target interval.

[0058] Optionally, after screening out all GNSS-R specular reflection points around the grid point that do not exceed the target space range as target points, the grid screening module is further configured to perform the following steps:

[0059] Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

[0060] Optionally, the device further comprises a building module configured to perform the following steps:

[0061] Collecting statistics on the altitude measurement accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by the observation satellite based on the GNSS signals transmitted by different types of signal sources on a global scale;

[0062] For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

[0063] Optionally, the calculation module is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average, specifically including:

[0064] Obtain the incident angle and effective wave height of the sea surface corresponding to the height measurement results of each target point;

[0065] Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy;

[0066] Determine the weight of the corresponding residual geoid height based on each height measurement accuracy;

[0067] Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

[0068] Optionally, the calculation module is configured to calculate the corresponding ocean vertical deviation based on the residual geoid height and the geoid height of each grid point, including:

[0069] Calculating residual vertical deviation based on residual geoid height of the grid point;

[0070] According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation;

[0071] Calculating the model vertical deviation based on the geoid height of the grid point;

[0072] The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

[0073] Optionally, after calculating the average residual geoid height of the grid points, the calculation module is further configured to perform the following steps:

[0074] When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval;

[0075] determining a sparsity factor based on the new target interval;

[0076] Based on the sparse multiple, a new target grid is generated on the basis of the old target grid;

[0077] Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting;

[0078] Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

[0079] According to a third aspect of an embodiment of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the method provided in the first aspect of the embodiment of the present application are implemented.

[0080] According to the fourth aspect of an embodiment of the present application, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, the steps in the method provided in the first aspect of the embodiment of the present application are implemented.

[0081] The ocean vertical deviation calculation method provided in the present application is adopted to calculate the residual geoid height of the GNSS-R mirror reflection point based on the height measurement results of each GNSS-R mirror reflection point in the ocean area obtained by GNSS-R height measurement, the geoid height and the average dynamic terrain. The global geographical area is divided according to the target interval of longitude and latitude to generate a target grid. For each grid point in the target grid, the residual geoid height of the grid point is calculated by weighted averaging based on multiple GNSS-R mirror reflection points around the grid point, and the weight corresponding to the data of different signal sources at each GNSS-R mirror reflection point is determined by looking up the GNSS-R height measurement accuracy table. Furthermore, the ocean vertical deviation is calculated by the residual geoid height and geoid height of each grid point, that is, the ocean vertical deviation based on the corresponding spatial resolution of the target grid is determined globally.

[0082] The method for calculating the ocean vertical line deviation provided in the present application adopts the method of grid division and weighted average to calculate the ocean vertical line deviation, aiming at the characteristics that the altimetry results of satellite-borne GNSS-R altimetry have diverse data sources and discontinuous GNSS-R mirror reflection point trajectories, so that the ocean vertical line deviation results can be calculated more conveniently.

[0083] In addition, taking into account the differences in height measurement accuracy under different GNSS signal sources, incident angles and sea surface effective wave height conditions, the present application pre-constructs a GNSS-R height measurement accuracy table based on the height measurement accuracy of multiple GNSS signal sources for weighted averaging weight determination, thereby achieving accurate weighting of data corresponding to different types of signal sources, and further improving the accuracy of the ocean vertical line deviation calculation results of the network points. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0085] Figure 1 is a flow chart of a method for calculating a GNSS-R ocean vertical deviation proposed in one embodiment of the present application;

[0086] Figure 2 It is the GNSS-R specular reflection point distribution and incident angle definition diagram;

[0087] Figure 3 It is a schematic diagram of geoid height, mean dynamic topography and GNSS-R sea surface height;

[0088] Figure 4 It is a schematic diagram for calculating the ocean vertical deviation;

[0089] Figure 5 is a schematic diagram of a GNSS-R ocean vertical deviation calculation device proposed in an embodiment of the present application;

[0090] Figure 6 It is a schematic diagram of an electronic device proposed in an embodiment of the present application. DETAILED DESCRIPTION

[0091] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions 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 creative work are within the scope of protection of this application.

[0092] It should be understood that the references to "one embodiment" or "an embodiment" throughout the specification mean that the specific features, structures, or characteristics associated with the embodiment are included in at least one embodiment of the present application. Therefore, the references to "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0093] In the various embodiments of the present application, it should be understood that the size of the serial numbers of the following processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0094] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects as detailed in the present application.

[0095] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0096] Traditional sea surface height measurement is achieved by actively transmitting and receiving signals through radar altimeters. However, this method has both a transmitting device and a receiving device, resulting in higher costs. In addition, since traditional radar altimeters can only measure sub-satellite points, it is difficult to achieve rapid global coverage. GNSS-R interferometric altimetry is a method in which observation satellites receive GNSS signals emitted by different types of navigation satellites (signal sources) reflected by the sea surface during movement, thereby achieving sea surface height measurement of GNSS-R mirror reflection points. Observation satellites can simultaneously receive multiple GNSS signals from multiple signal sources without transmitting signals. Therefore, this method has the advantages of wide coverage, low cost, easy networking, and is conducive to rapid global coverage and revisits.

[0097] However, the height measurement accuracy of the sea surface height data products generated by GNSS-R interferometric height measurement technology is closely related to many factors such as the satellite incidence angle, the type of signal source navigation system, and the effective wave height of the sea surface. In addition, the observation trajectory of the sea surface height data products is closely related to the visible time of the navigation satellite and cannot be continuous for a long time.

[0098] This application uses the gridded weighted average of data from multiple GNSS-R mirror reflection points to calculate the ocean vertical deviation, which can effectively improve the calculation efficiency of the GNSS-R vertical deviation, integrate multiple observation results from multiple GNSS signal sources, and realize accurate calculation of the global ocean vertical deviation.

[0099] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0100] Figure 1 : is a flow chart of a method for calculating a GNSS-R ocean vertical deviation proposed in one embodiment of the present application. Figure 1 As shown, the method includes:

[0101] S1: Obtain the altimetry results, geoid height and average dynamic topography of each GNSS-R mirror reflection point in the ocean area, and calculate the residual geoid height of each GNSS-R mirror reflection point;

[0102] S2: Divide the global geographical area according to the target interval of longitude and latitude to generate the target grid;

[0103] S3: for any grid point in the target grid, select a plurality of GNSS-R specular reflection points around the grid point as the target point;

[0104] S4: Determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; the GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incident angles and sea surface effective wave height conditions;

[0105] S5: Based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated.

[0106] In this embodiment, the sea surface height measurement results of all GNSS-R mirror reflection points measured by the observation satellite based on the GNSS-R method in the global ocean area, as well as the geoid height and average dynamic topography of each GNSS-R mirror reflection point are first obtained. The geoid height is the distance from the geoid along the normal to the surface of the earth ellipsoid. For the geoid height, this embodiment is based on the EGM (Earth Gravitational Mode, Earth Gravity Model) reference model, and is obtained according to the longitude and latitude of the GNSS-R mirror reflection point. The mean dynamic topography (MDT) is the difference between the multi-year average sea surface height and the geoid, which can be obtained by calculating the average sea surface height for many years. This embodiment is based on the average sea surface dynamic topography model, and is obtained according to the longitude and latitude of the GNSS-R mirror reflection point. Based on the sea surface height (height measurement result), geoid height and average dynamic topography of the GNSS-R mirror reflection point, the residual geoid height at the GNSS-R mirror reflection point is calculated.

[0107] In this embodiment, the longitude and latitude of the global geographical area are evenly divided according to the target interval to generate a target grid. The vertical deviation of the global ocean area is obtained by calculating the ocean vertical deviation of all grid points in the target grid.

[0108] For each grid point in the target grid, multiple GNSS-R mirror reflection points around the grid point are used as the target point corresponding to the grid point, and the residual geoid heights of these target points are weighted averaged to determine the residual geoid height at the grid point. Considering that the residual geoid heights at different GNSS-R mirror reflection points may be calculated based on the height measurement results of different signal sources, a GNSS-R height measurement accuracy table is pre-constructed based on the height measurement accuracy of the GNSS-R height measurement results of different signal sources in this embodiment. When calculating the weighted average, the height measurement accuracy of the corresponding signal source is determined by searching the GNSS-R height measurement accuracy table according to the height measurement results of each target point, and then the weight corresponding to the residual geoid height is determined according to the height measurement accuracy. A weighted average calculation is performed based on the residual geoid heights of each target point and the corresponding weights to obtain the residual geoid height at the grid point.

[0109] According to the longitude and latitude of each grid point, the geoid height of the grid point is obtained, and the ocean vertical deviation at each grid point is calculated based on the geoid height and the residual geoid height, so as to obtain the global ocean vertical deviation data product based on the target grid. In practical applications, the target interval used to generate the target grid can be set according to actual needs. The size of the target interval is related to the spatial resolution of the ocean vertical deviation data product that the user wants to generate. The smaller the target interval setting, the higher the density of the target grid, the higher the spatial resolution of the ocean vertical deviation, but the greater the amount of calculation. Conversely, the larger the target interval setting, the lower the density of the target grid, the lower the spatial resolution of the ocean vertical deviation, and the less the amount of calculation.

[0110] In this embodiment, the method for calculating the global ocean vertical deviation based on the GNSS-R sea surface altimetry results adopts a vertical deviation inversion algorithm suitable for the characteristics of GNSS-R data. According to the characteristics of GNSS-R with a large reflection area, fast global coverage, high revisit, and constantly changing incident angle azimuth, the weighted average of the data of multiple GNSS-R mirror reflection points around the network point is used to replace the traditional altimeter along-track least squares method, and the accuracy and efficiency of calculating the ocean vertical deviation are effectively improved by averaging multiple measurement results.

[0111] In addition, in the process of calculating the residual geoid height of the network point, the present application also takes into account the influence of different GNSS signal transmission sources on the height measurement accuracy. For example, the GNSS-R interferometric height measurement accuracy of BDS (BeiDou Navigation Satellite System), GPS (Global Positioning System) and GAL (Galileo satellite navigation system) is different due to differences in system bandwidth, incident angle and effective wave height of the sea surface. Based on this, a GNSS-R height measurement accuracy table for different signal sources is constructed in this embodiment. By looking up the GNSS-R height measurement accuracy table of the corresponding signal source, the weight of the residual geoid height of the GNSS-R mirror reflection point in the weighted average is determined, thereby further improving the accuracy of the calculation of the ocean vertical deviation.

[0112] As an implementation mode of the present application, obtaining the height measurement results of multiple GNSS-R mirror reflection points measured by an observation satellite in an ocean area based on GNSS signals includes:

[0113] Acquire a sea surface height data product measured by GNSS-R; the sea surface height data product includes: the height measurement results of all GNSS-R specular reflection points measured globally by the observation satellite based on GNSS signals; each height measurement result has a corresponding incident angle;

[0114] Based on a first threshold, removing sea surface height measurement results having an incident angle greater than the first threshold from the sea surface height data product;

[0115] Based on the actual observation area of ​​each GNSS-R mirror reflection point, the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface are eliminated from the sea surface height data product; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as the side lengths.

[0116] In one embodiment, the sea surface height measurement results of multiple days by the satellite-borne GNSS-R are used to calculate the residual geoid height at the GNSS-R mirror reflection point based on the geoid height obtained based on the earth's gravity model and the average sea surface dynamic terrain model as input auxiliary data.

[0117] In this embodiment, the GNSS-R sea surface height product (a sea surface height data product obtained based on the global navigation satellite system reflection measurement technology) is first screened. The amount of relevant sea surface height product data is large. In order to ensure the timeliness and accuracy of the calculation results, the secondary sea surface height data product of GNSS-R altimetry within the target time range is selected, and the quality code of the data product is ensured to be good. The target time range can be set according to actual needs. In order to ensure the timeliness of the calculation of the ocean vertical deviation, a relatively close time range can be set as the target time range.

[0118] Figure 2 This is the GNSS-R mirror reflection point distribution and incident angle definition diagram. Figure 2 As shown in Figure 2, the incident angles of the GNSS signals reflected from different GNSS-R mirror reflection points received by the observation satellite are ( Figure 2 α) is constantly changing. Considering that an excessively large incident angle will lead to poor accuracy of the altimetry results, in order to ensure the accuracy of the subsequent calculation of the ocean vertical deviation, the altimetry result data is pre-screened based on the incident angle, and the sea surface height measurement results with an incident angle greater than the first threshold are eliminated, and the altimetry results with an incident angle less than or equal to the first threshold are retained. In practical applications, the first threshold can be set according to the actual calculated altimetry accuracy requirements, and this application does not impose any restrictions on this. Optionally, the first threshold is set to 35°, that is, the sea surface altimetry data with α≤35° is screened.

[0119] The sea surface height data product also includes reflection points on land and glaciers. In order to obtain the ocean vertical deviation in the ocean area, it is also necessary to filter out the height measurement results where the observation area is completely on the sea surface. The actual observation area of ​​the GNSS-R mirror reflection point is a rectangular area, which is centered on the GNSS-R mirror reflection point, with the cross-track direction and the along-track direction as the parallel directions of the rectangular sides, and the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as the side lengths to form an equivalent rectangular area. By detecting whether the actual observation area of ​​each GNSS-R mirror reflection point is completely on the sea surface, the height measurement result data where some observation areas are not on the sea surface, and the entire observation area is not on the sea surface are eliminated, and finally the height measurement result data of the GNSS-R mirror reflection point where the observation area is completely on the sea surface is obtained.

[0120] In this embodiment, the sea surface height data products are screened based on factors such as time range, incident angle and actual observation area, thereby reducing the amount of calculated data when subsequently calculating the global ocean vertical deviation based on the target grid, thereby improving the calculation efficiency and accuracy of the ocean vertical deviation.

[0121] As an implementation of the present application, calculating the residual geoid height of each GNSS-R mirror reflection point includes:

[0122] Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0123] Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0124] Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

[0125] In one embodiment, the MDT average sea surface dynamic terrain model and the EGM earth gravity model are obtained. According to the EGM model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the point is obtained by bilinear interpolation. According to the MDT model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain at the point is obtained by bilinear interpolation.

[0126] The sea surface height h of the GNSS-R mirror reflection point is expressed as:

[0127] h=N REF +ΔN+h MDT +ζ(t)+e.

[0128] Where, h is the sea surface height measurement result of GNSS-R (direct observation data), that is, the distance from the GNSS-R mirror reflection point to the reference ellipsoid; N REF represents the reference geoid; h MDT represents the average dynamic topography; ΔN represents the reference geoid residual; ζ(t) represents the time-varying sea surface topography; e is the sea surface height error. The sum of ΔN and ζ(t) is collectively referred to as the residual geoid height Δh.

[0129] Figure 3 This is a schematic diagram of geoid height, mean dynamic terrain and GNSS-R sea surface height. Figure 3 As shown in the figure, the measurement result of the sea surface height h is the data actually measured at the GNSS-R mirror reflection point, and the average dynamic terrain and geoid height are auxiliary data obtained based on the model. Based on the sea surface height measurement results, geoid height and average dynamic terrain of the GNSS-R mirror reflection point, the "remove-restore" method can be used to subtract the geoid height and average dynamic terrain from the sea surface height measurement results to obtain the residual geoid height Δh at the point.

[0130] As an implementation manner of the present application, screening a plurality of GNSS-R specular reflection points around the network point as target points includes:

[0131] Based on the target spatial range, all GNSS-R specular reflection points around the network point that do not exceed the target spatial range are screened out as target points; the target spatial range is an area enclosed by a side length whose longitude and latitude from the network point is not less than half of the target interval.

[0132] In one embodiment, all GNSS-R specular reflection points in the target grid whose distance to the grid point is less than the target space range are screened out as the target points of the grid point. Specifically, the GNSS-R height measurement results are screened for data of each grid point according to the following expression:

[0133] S={Sample i |Lat min ≤Lat i ≤Lat max ;Lon min ≤Lon i ≤Lon max}.

[0134] Where S is the set of all target points that meet the spatial requirements of a certain network point; Lat represents latitude, Lon represents longitude; Sample i The corresponding space coordinates are (Lat i ,Lon i ) target point.

[0135] The target spatial range is the area enclosed by the latitude and longitude boundaries with the grid point as the center and the target interval as the area. The GNSS-R mirror reflection point in the area is used as the target point of the grid point. The residual geoid height data of all target points are weighted averaged to obtain the residual geoid height of the grid point. That is, the residual geoid height data of the GNSS-R mirror reflection points on the ocean in the global range are mapped to each grid point of the target grid by weighted average, so as to realize the accurate calculation of the residual geoid height on the grid point.

[0136] As an implementation manner of the present application, after screening out all GNSS-R specular reflection points around the network point that do not exceed the target space range as target points, it also includes:

[0137] Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

[0138] In one embodiment, the residual geoid height data of the target point may be further screened according to the target time range, so as to calculate the ocean vertical deviation of the target grid based on the data of the target point that meets the spatial requirements within the specified time range.

[0139] In this embodiment, the GNSS-R height measurement results are filtered point by point according to the following expression:

[0140]

[0141] Among them, S is the set of all target points that meet the time and space requirements of a certain network point; Lat represents latitude, Lon represents longitude, and T represents time; Sample i The corresponding space-time coordinates are (Lat i ,Lon i ,T i ) target point.

[0142] As an implementation manner of the present application, before determining the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, it also includes:

[0143] Collecting statistics on the altitude measurement accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by the observation satellite based on the GNSS signals transmitted by different types of signal sources on a global scale;

[0144] For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

[0145] In practical applications, the GNSS-R sea level height result has a more complex observation state. In addition to the influence of the signal source on the height measurement accuracy, the different incident angles and sea surface conditions of the GNSS signal will also affect the height measurement accuracy. For example, even if the same sea surface condition corresponds to different incident angles, there will be different error corrections and height measurement accuracy results. Generally, the increase in the incident angle will lead to a decrease in height measurement accuracy. Based on this, in this embodiment, the influence of the sea surface condition and the different incident angles and signal sources on the observation results is comprehensively evaluated. According to the height measurement data products of different signal sources, third-party external data sources, etc., the GNSS-R calibration comparison data is analyzed to construct a two-dimensional lookup table of the height measurement accuracy of the GNSS-R sea level product for each signal source regarding the incident angle of the GNSS-R mirror reflection point and the effective wave height of the sea surface, that is, the GNSS-R height measurement accuracy table. When calculating the residual geoid height of the network point, the GNSS-R height measurement accuracy table of the corresponding signal source is searched to achieve the reasonable weighting of the residual geoid height of each target point.

[0146] As an implementation of the present application, the weight of the residual geoid height of each target point is determined based on the GNSS-R height measurement accuracy table, and the residual geoid height of the network point is calculated by weighted average, including:

[0147] Obtain the incident angle and effective wave height of the sea surface corresponding to the height measurement results of each target point;

[0148] Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy;

[0149] Determine the weight of the corresponding residual geoid height based on each height measurement accuracy;

[0150] Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

[0151] In one embodiment, the incident angle and the effective sea wave height corresponding to the height measurement results of the target points around the grid points in the target grid are obtained, and based on the incident angle and the effective sea wave height, the GNSS-R height measurement accuracy table of the corresponding signal source is searched to obtain the height measurement accuracy. Optionally, the height measurement accuracy σ of each target point is obtained by a two-dimensional linear interpolation method based on the obtained height measurement accuracy. i .

[0152] Furthermore, the weight corresponding to the residual geoid height of the target point is determined based on the obtained height measurement accuracy, which is used to calculate the weighted average of the data on multiple target points. According to the residual geoid heights of all target points corresponding to the grid point, the corresponding residual geoid height ΔH is calculated:

[0153]

[0154] Where Δh i is the residual geoid height value of the i-th target point, σ i is the estimated value of the sea surface height measurement error of the i-th target point (height measurement accuracy).

[0155] Optionally, since the points in the target grid cover the global geographical area, when calculating the residual geoid height of the points, the residual geoid height of the points in the target grid that are in non-ocean areas is directly set to empty, thereby improving the calculation efficiency and accuracy of the ocean vertical deviation.

[0156] As an implementation mode of the present application, based on the residual geoid height and the geoid height of each grid point, the corresponding ocean vertical deviation is calculated, including:

[0157] Calculating residual vertical deviation based on residual geoid height of the grid point;

[0158] According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation;

[0159] Calculating the model vertical deviation based on the geoid height of the grid point;

[0160] The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

[0161] In one embodiment, the corresponding residual vertical deviation is calculated according to the residual geoid height of the grid point, and the model vertical deviation is calculated according to the geoid height of each grid point in the target grid. Figure 4 is a schematic diagram for calculating the ocean vertical deviation. Figure 4 As shown in the figure, let the components of the vertical deviation θ in the meridian plane and the meridian plane be: ζ res and η res , then according to the distance dS between two adjacent points P and P1 on the target grid, the two components ξ of the vertical deviation in the meridian plane and the zenithal plane are calculated respectively. res and η res :

[0162]

[0163]

[0164] in, dN λ They represent the residual geoid height difference between two adjacent points P and P1 on the meridian plane and the meridian plane on the target grid, respectively. dSλ Respectively represent the distances between two adjacent points P and P1 on the meridian plane and the meridian plane on the target grid; R is the radius of the earth; dλ is the difference in latitude and longitude between two adjacent points P and P1 on the meridian plane and the meridian plane of the target grid.

[0165] Similarly, according to the EGM earth gravity model and the longitude and latitude of the network point, the reference geoid height of the network point is calculated by bilinear interpolation, and the two components ξ of the corresponding model vertical deviation in the meridian plane and the meridian plane are calculated based on the geoid height. model and η model .

[0166] Finally, the two components ξ and η of the ocean vertical deviation in the meridian plane and the zenithal plane are restored according to the “remove-restore” method to obtain the ocean vertical deviation of the network point:

[0167] ξ=ξ model +ξ res ;

[0168] η=η model +η res .

[0169] As an implementation manner of the present application, after calculating the average residual geoid height of the grid points, the method further includes:

[0170] When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval;

[0171] determining a sparsity factor based on the new target interval;

[0172] Based on the sparse multiple, a new target grid is generated on the basis of the old target grid;

[0173] Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting;

[0174] Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

[0175] In one embodiment, when the target interval is enlarged, a new target grid is obtained by thinning out on the basis of the old target grid, and the residual geoid height of each grid point on the new target grid is calculated based on the residual geoid height of each grid point on the old target grid. First, the thinning multiple required for the current target grid is determined based on the new target interval and the old target interval. For example, if the target grid is a 5′ grid and needs to be thinned out to a 20′ grid or a 1° grid, the corresponding thinning multiple is determined.

[0176] Then, based on the rarefaction multiple, the 20′ grid or 1° grid is thinned out on the basis of the 5′ grid. Based on the residual geoid height data of each grid point in the 5′ grid, the residual geoid height of each grid point in the 20′ grid or 1° grid is calculated by the inverse distance weighted method. At the same time, according to the EGM reference model, the model geoid height of the 20′ grid or 1° grid is determined by bilinear interpolation. Based on the residual geoid height of the 20′ grid or 1° grid and the model geoid height, the corresponding ocean vertical deviation is calculated.

[0177] In this embodiment, when the spacing between adjacent grid points in the target grid changes, the residual geoid height of the grid points in the new grid is calculated by weighted average based on the data of each grid point in the current grid (old grid) according to the sparse multiple between the new grid and the old grid. This eliminates the steps of re-screening the target points of each grid point in the new grid, finding and determining the weights by height measurement accuracy, and weighted average calculation, thus saving computing resources and improving computing efficiency.

[0178] As an implementation manner of the present application, the target interval is greater than the maximum value of the cross-track spatial resolution and the along-track spatial resolution corresponding to the height measurement results of each GNSS-R mirror reflection point.

[0179] In one embodiment, the corresponding target interval is determined according to the maximum value of the cross-track spatial resolution and the along-track spatial resolution corresponding to the altimetry results of each GNSS-R mirror reflection point on the sea surface, and a basic grid is generated. The ocean vertical deviation is calculated based on the basic grid to obtain the ocean vertical deviation data product with the highest spatial resolution. Furthermore, the basic grid can be sparsely operated according to user needs, and a variety of ocean vertical deviation data products with lower spatial resolution can be quickly solved based on the ocean vertical deviation data product with the highest spatial resolution, without re-screening the target points for weighted average calculation and other operations, which saves calculation amount and improves the calculation efficiency of the ocean vertical deviation.

[0180] For example, the target interval of the basic grid is 2.5′, and the grid is further thinned according to the needs of different users (such as 5' grid, 20' grid, 1° grid, etc.). The residual geoid height of the grid points is obtained using the inverse distance weighted method, and the ocean vertical deviation is further calculated to obtain a low-resolution ocean vertical deviation data product.

[0181] Based on the same inventive concept, an embodiment of the present application provides a GNSS-R ocean vertical deviation calculation device. Figure 5 , Figure 5 FIG. 1 is a schematic diagram of a GNSS-R ocean vertical deviation calculation device 100 proposed in an embodiment of the present application. Figure 5 As shown, the device comprises:

[0182] The preprocessing module 101 is configured to obtain the altimetry results, geoid height and average dynamic topography of each GNSS-R mirror reflection point in the ocean area based on GNSS-R, and calculate the residual geoid height of each GNSS-R mirror reflection point;

[0183] The grid generation module 102 is configured to divide the global geographical area according to the target interval of longitude and latitude to generate a target grid;

[0184] The grid screening module 103 is configured to screen, for any grid point in the target grid, a plurality of GNSS-R specular reflection points around the grid point as a target point;

[0185] The calculation module 104 is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; the GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incident angles and sea surface effective wave height conditions; based on the residual geoid height and geoid height of each network point, calculate the corresponding ocean vertical deviation.

[0186] As an implementation manner of the present application, the preprocessing module 101 includes:

[0187] The acquisition submodule is configured to obtain sea surface height data products of GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points measured globally by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle;

[0188] The first screening submodule is configured to, based on a first threshold, eliminate from the sea surface height data product the sea surface height measurement results whose incident angles are greater than the first threshold; based on the actual observation area of ​​each GNSS-R mirror reflection point, eliminate from the sea surface height data product the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as side lengths.

[0189] As an implementation manner of the present application, the preprocessing module 101 further includes a first calculation submodule, which is configured to perform the following steps:

[0190] Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0191] Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation;

[0192] Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

[0193] As an implementation mode of the present application, the grid screening module 103 is specifically configured to screen out all GNSS-R mirror reflection points around the grid point that do not exceed the target space range as target points based on the target space range; the target space range is an area enclosed by a side length whose longitude and latitude from the grid point is not less than half of the target interval.

[0194] As an implementation manner of the present application, after screening out all GNSS-R specular reflection points around the grid point that do not exceed the target space range as target points, the grid screening module 103 is further configured to perform the following steps:

[0195] Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

[0196] As an embodiment of the present application, the device further includes a building module configured to perform the following steps:

[0197] Collecting statistics on the altitude measurement accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by the observation satellite based on the GNSS signals transmitted by different types of signal sources on a global scale;

[0198] For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

[0199] As an implementation manner of the present application, the calculation module 104 is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average, specifically including:

[0200] Obtain the incident angle and effective wave height of the sea surface corresponding to the height measurement results of each target point;

[0201] Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy;

[0202] Determine the weight of the corresponding residual geoid height based on each height measurement accuracy;

[0203] Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

[0204] As an implementation of the present application, the calculation module 104 is configured to calculate the corresponding ocean vertical deviation based on the residual geoid height and the geoid height of each grid point, including:

[0205] Calculating residual vertical deviation based on residual geoid height of the grid point;

[0206] According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation;

[0207] Calculating the model vertical deviation based on the geoid height of the grid point;

[0208] The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

[0209] As an implementation manner of the present application, after calculating the average residual geoid height of the grid point, the calculation module 104 is further configured to perform the following steps:

[0210] When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval;

[0211] determining a sparsity factor based on the new target interval;

[0212] Based on the sparse multiple, a new target grid is generated on the basis of the old target grid;

[0213] Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting;

[0214] Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

[0215] Based on the same inventive concept, an embodiment of the present application provides a readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the method for calculating the ocean vertical deviation as described in any of the above embodiments of the present application are implemented.

[0216] Based on the same inventive concept, an embodiment of the present application provides an electronic device, referring to Figure 6 , Figure 6 : is a schematic diagram of an electronic device proposed in one embodiment of the present application. The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and when the computer program is executed by the processor, the steps in the GNSS-R ocean vertical deviation calculation method described in any of the above embodiments of the present application are implemented.

[0217] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0218] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0219] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the order of the actions described, because according to the present application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present application.

[0220] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the embodiments of the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0221] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0222] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer readable memory produce a manufactured product including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0223] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, thereby providing instructions for executing on the computer or other programmable terminal device to implement the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0224] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the present application is interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0225] Finally, it should be noted that, in this article, relational terms such as first and second, etc. 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 terminal 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 terminal 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 terminal device including the elements.

[0226] The above is a detailed introduction to the GNSS-R ocean vertical deviation calculation method, device, equipment and storage medium provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A GNSS-R ocean vertical deviation calculation method, characterized in that: include: Obtain the altimetry results, geoid height and average dynamic topography of each GNSS-R mirror reflection point in the ocean area, and calculate the residual geoid height of each GNSS-R mirror reflection point; Divide the global geographical area according to the target interval of longitude and latitude to generate the target grid; For any grid point in the target grid, multiple GNSS-R specular reflection points around the grid point are selected as the target point; Determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; The GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incident angles and sea surface effective wave height conditions; Based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated.

2. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: Obtain the height measurement results of multiple GNSS-R mirror reflection points measured by observation satellites in the ocean area based on GNSS signals, including: Acquire a sea surface height data product measured by GNSS-R; the sea surface height data product includes: the height measurement results of all GNSS-R specular reflection points measured globally by the observation satellite based on GNSS signals; each height measurement result has a corresponding incident angle; Based on a first threshold, removing sea surface height measurement results having an incident angle greater than the first threshold from the sea surface height data product; Based on the actual observation area of ​​each GNSS-R mirror reflection point, the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface are eliminated from the sea surface height data product; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as the side lengths.

3. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: Calculate the residual geoid height for each GNSS-R specular reflection point, including: Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation; Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation; Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

4. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: Screen multiple GNSS-R specular reflection points around the network point as target points, including: Based on the target spatial range, all GNSS-R specular reflection points around the network point that do not exceed the target spatial range are screened out as target points; the target spatial range is an area enclosed by a side length whose longitude and latitude from the network point is not less than half of the target interval.

5. The GNSS-R ocean vertical deviation calculation method according to claim 4, characterized in that: After selecting all GNSS-R mirror reflection points around the network point that do not exceed the target space range as target points, the method further includes: Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

6. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: Before determining the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, it also includes: Collect statistics on the altitude accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by observation satellites based on GNSS signals transmitted by different types of signal sources around the world; For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

7. The GNSS-R ocean vertical deviation calculation method according to claim 6, characterized in that: The weight of the residual geoid height of each target point is determined based on the GNSS-R height measurement accuracy table, and the residual geoid height of the network point is calculated by weighted average, including: Obtain the incident angle and effective sea surface wave height corresponding to the height measurement results of each target point; Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy; Determine the weight of the corresponding residual geoid height based on each height measurement accuracy; Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

8. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: Based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated, including: Calculating residual vertical deviation based on residual geoid height of the grid point; According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation; Calculating the model vertical deviation based on the geoid height of the grid point; The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

9. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: After calculating the average residual geoid height of the grid points, further comprising: When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval; determining a sparsity factor based on the new target interval; Based on the sparse multiple, a new target grid is generated on the basis of the old target grid; Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting; Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

10. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that: The target interval is greater than the maximum value of the cross-track spatial resolution and the along-track spatial resolution corresponding to the height measurement results of each GNSS-R mirror reflection point.

11. A GNSS-R ocean vertical deviation calculation device, characterized in that: include: The preprocessing module is configured to obtain the altimetry results, geoid height and average dynamic terrain of each GNSS-R mirror reflection point in the ocean area based on GNSS-R, and calculate the residual geoid height of each GNSS-R mirror reflection point; A grid generation module is configured to divide the global geographic area according to target intervals of longitude and latitude to generate a target grid; A grid screening module is configured to screen, for any grid point in the target grid, a plurality of GNSS-R specular reflection points around the grid point as a target point; A calculation module is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average; The GNSS-R height measurement accuracy table is constructed based on the height measurement accuracy of different GNSS signal sources under different incidence angles and sea surface effective wave height conditions; based on the residual geoid height and geoid height of each grid point, the corresponding ocean vertical deviation is calculated.

12. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: The preprocessing module comprises: The acquisition submodule is configured to obtain sea surface height data products of GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points measured globally by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle; The first screening submodule is configured to, based on a first threshold, eliminate from the sea surface height data product the sea surface height measurement results whose incident angles are greater than the first threshold; based on the actual observation area of ​​each GNSS-R mirror reflection point, eliminate from the sea surface height data product the height measurement results of the GNSS-R mirror reflection points whose actual observation area is not completely on the sea surface; the actual observation area is a rectangular area enclosed by the GNSS-R cross-track spatial resolution and the GNSS-R along-track spatial resolution as side lengths.

13. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: The preprocessing module further includes a first calculation submodule configured to perform the following steps: Based on the earth gravity model and the longitude and latitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation; Based on the average sea surface dynamic terrain model and the longitude and latitude of the GNSS-R mirror reflection point, the average dynamic terrain of the GNSS-R mirror reflection point is obtained by bilinear interpolation calculation; Based on the altimetry results of the GNSS-R mirror reflection points, the geoid height and the average dynamic topography, the residual geoid height of each GNSS-R mirror reflection point is calculated.

14. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: The grid screening module is specifically configured to screen out all GNSS-R specular reflection points around the grid point that do not exceed the target space range as target points based on the target space range; The target space range is an area enclosed by a side length whose longitude and latitude from the network point is not less than half of the target interval.

15. The GNSS-R ocean vertical deviation calculation device according to claim 14, characterized in that: After selecting all GNSS-R specular reflection points around the grid point that do not exceed the target space range as target points, the grid screening module is further configured to perform the following steps: Based on the target time range, the residual geoid height of each target point within the target time range is screened out.

16. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: The apparatus further comprises a building block configured to perform the following steps: Collect statistics on the altitude accuracy, incident angle and effective wave height of the sea surface corresponding to the altitude measurement results obtained by observation satellites based on GNSS signals transmitted by different types of signal sources around the world; For each type of signal source, a two-dimensional GNSS-R height measurement accuracy table is constructed according to the variation law of the height measurement accuracy of the height measurement result corresponding to the signal source with the incident angle and the effective wave height of the sea surface; each combination of the incident angle and the effective wave height of the sea surface in the GNSS-R height measurement accuracy table corresponds to a unique height measurement accuracy.

17. The GNSS-R ocean vertical deviation calculation device according to claim 16, characterized in that: The calculation module is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R height measurement accuracy table, and calculate the residual geoid height of the network point by weighted average, specifically including: Obtain the incident angle and effective sea surface wave height corresponding to the height measurement results of each target point; Based on the incident angle and the effective wave height of the sea surface, searching the GNSS-R height measurement accuracy table to obtain the corresponding height measurement accuracy; Determine the weight of the corresponding residual geoid height based on each height measurement accuracy; Based on the residual geoid height of each target point and the corresponding weight, the residual geoid height of the network point is calculated by weighted average.

18. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: The calculation module is configured to calculate the corresponding ocean vertical deviation based on the residual geoid height and the geoid height of each grid point, including: Calculating residual vertical deviation based on residual geoid height of the grid point; According to the earth gravity model and the longitude and latitude of the network point, the geoid height of the network point is obtained by bilinear difference calculation; Calculating the model vertical deviation based on the geoid height of the grid point; The ocean vertical deviation of the grid point is calculated based on the residual vertical deviation and the model vertical deviation.

19. The GNSS-R ocean vertical deviation calculation device according to claim 11, characterized in that: After calculating the average residual geoid height of the grid points, the calculation module is further configured to perform the following steps: When the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval; determining a sparsity factor based on the new target interval; Based on the sparse multiple, a new target grid is generated on the basis of the old target grid; Based on the residual geoid height of each grid point in the old target grid, the residual geoid height of each grid point in the new target grid is calculated by inverse distance weighting; Based on the residual geoid height and the geoid height of each grid point in the new target grid, the corresponding ocean vertical deviation is calculated.

20. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps in the method according to any one of claims 1 to 10 are implemented.

21. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps in the method according to any one of claims 1 to 10 are implemented.

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