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

Abstract

The application relates to the technical field of satellite height measurement, and discloses a GNSS-R ocean vertical deviation calculation method, device, equipment and storage medium. The method comprises the following steps: acquiring height measurement results, geodetic datum plane heights and average dynamic topographies of each GNSS-R mirror reflection point in an ocean area, and calculating residual geodetic datum plane heights; a global geographical area is divided according to a target interval of longitude and latitude to generate a target grid; for any grid point in the target grid, a plurality of GNSS-R mirror reflection points around the grid point are selected as target points; the weights of the residual geodetic datum plane heights of the target points are determined based on a GNSS-R height measurement accuracy table, the residual geodetic datum plane heights of the grid points are calculated through weighted average, and the corresponding ocean vertical deviations are further calculated. The method can realize rapid calculation of global ocean vertical deviations based on GNSS-R sea surface height measurement results, and improves the accuracy of ocean vertical deviation calculation.

Description

Technical Field

[0001] This application relates to the field of satellite altimetry technology, and in particular to a GNSS-R method, apparatus, equipment and storage medium for calculating ocean vertical deviation. Background Technology

[0002] Vertical deviation is fundamental data for numerous applications, including Earth's gravity field inversion, elevation anomaly calculation, and precision engineering surveying; accurate measurement of vertical deviation is crucial. Traditional shipborne and airborne gravity field measurement methods have limited capabilities for large-scale global measurements. Gravity measurement satellites have greatly advanced this field by providing high-precision gravity data globally on a monthly basis; however, they primarily capture mid-to-long-wave information of the gravity field (approximately 300 km) and are less sensitive to short-wave signals. Satellite altimetry contains valuable high-frequency information about the Earth's gravity field, and inverting ocean vertical deviation and gravity anomalies from satellite radar altimetry significantly improves the accuracy and spatial resolution of ocean gravity field inversion. However, satellite altimetry is costly, and forming a large-scale constellation network for high-time-efficiency detection remains a challenge.

[0003] In recent years, the emerging GNSS-R interferometric altimetry technology has provided a new method for measuring shortwave gravity fields. The observation satellite can simultaneously receive multiple GNSS signals from various signal sources without transmitting signals. Therefore, this method has advantages such as wide coverage, low cost, easy networking, and facilitates rapid global coverage and revisit.

[0004] However, the altimeter accuracy of sea surface height data products generated by GNSS-R interferometric altimetry is closely related to multiple factors, including the satellite incident angle, the type of navigation system from the signal source, and the significant wave height of the sea surface. Furthermore, the observation trajectory of the sea surface height data products is closely related to the visibility duration of the navigation satellites. Because the observation trajectory cannot be continuous for extended periods, accurate calculation of global ocean vertical deviation is difficult. Therefore, how to achieve accurate calculation of global ocean vertical deviation based on spaceborne GNSS-R sea surface altimeter results is a problem that needs to be solved. Summary of the Invention

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

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

[0007] The first aspect of this application provides a method for calculating the vertical deviation of a GNSS-R ocean line, the method comprising:

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

[0009] The global geographic region is divided according to the target intervals of latitude and longitude, generating a target grid;

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

[0011] The weights of the residual geoid heights of each target point are determined based on the GNSS-R altimeter accuracy table, and the residual geoid heights of the network points are calculated by weighted averaging. The GNSS-R altimeter accuracy table is constructed based on the altimeter accuracy of different GNSS signal sources under different incident angles and sea surface significant wave height conditions.

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

[0013] Optionally, obtain the height measurement results of multiple GNSS-R specular reflection points in the ocean area based on GNSS signals from observation satellites, including:

[0014] Acquire sea surface height data products from GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points globally measured by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle;

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

[0016] Based on the actual observation area of ​​each GNSS-R specular reflection point, the height measurement results of GNSS-R specular reflection points whose actual observation area is not completely on the sea surface are removed 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 side lengths.

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

[0018] Based on the Earth's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation.

[0019] Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation.

[0020] Based on the height measurement 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, multiple GNSS-R specular reflection points around the grid point are selected as target points, including:

[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 selected as target points; the target spatial range is an area enclosed by a side length that is not less than half of the target interval at a distance of latitude and longitude from the network point.

[0023] Optionally, after selecting all GNSS-R specular reflection points around the grid points 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 selected.

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

[0026] Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on the altimeter results obtained by the observation satellite using GNSS signals emitted from different types of signal sources.

[0027] For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

[0028] Optionally, the weights of the residual geoid heights of each target point are determined based on the GNSS-R altimeter accuracy table, and the residual geoid heights of the network points are calculated by weighted averaging, including:

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

[0030] Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by consulting the GNSS-R altimetry accuracy table.

[0031] The weight of the corresponding residual geoid height is determined based on the altimetry accuracy.

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

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

[0034] Based on the residual geoid height of the network points, calculate the residual vertical deviation;

[0035] Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation.

[0036] Based on the geoid height of the network points, the vertical deviation of the model is calculated.

[0037] Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

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

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

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

[0041] Based on the sparsity factor, a new target grid is generated on the basis of the old target grid.

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

[0043] Based on the residual geoid height and geoid height of each 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 the embodiments of this application, a GNSS-R marine vertical deviation calculation device is provided, the device comprising:

[0046] The preprocessing module is configured to acquire the GNSS-R altimeter results, geoid height, and mean dynamic topography of each GNSS-R specular reflection point in the marine area, and to calculate the residual geoid height of each GNSS-R specular reflection point.

[0047] The grid generation module is configured to divide global geographic regions according to target intervals of latitude and longitude, and generate target grids;

[0048] The grid filtering module is configured to, for any point in the target grid, filter multiple GNSS-R specular reflection points around the point as target points;

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

[0050] Optionally, the preprocessing module includes:

[0051] The acquisition submodule is configured to acquire sea surface height data products from GNSS-R altimetry measurements; 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 filtering submodule is configured to, based on a first threshold, remove sea surface height measurement results from the sea surface height data product whose incident angle is greater than the first threshold; and based on the actual observation area of ​​each GNSS-R specular reflection point, remove height measurement results from the sea surface height data product for GNSS-R specular 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's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation.

[0055] Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation.

[0056] Based on the height measurement 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 filtering module is specifically configured to filter out all GNSS-R specular 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 that is not less than half of the target interval at a distance of latitude and longitude from the grid point.

[0058] Optionally, 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 filtering 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 selected.

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

[0061] Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on the altimeter results obtained by the observation satellite using GNSS signals emitted from different types of signal sources.

[0062] For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

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

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

[0065] Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by consulting the GNSS-R altimetry accuracy table.

[0066] The weight of the corresponding residual geoid height is determined based on the altimetry accuracy.

[0067] Based on the residual geoid height and corresponding weight of each target point, the residual geoid height of the network points 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 geoid height of each network point, including:

[0069] Based on the residual geoid height of the network points, calculate the residual vertical deviation;

[0070] Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation.

[0071] Based on the geoid height of the network points, the vertical deviation of the model is calculated.

[0072] Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

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

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

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

[0076] Based on the sparsity factor, a new target grid is generated on the basis of the old target grid.

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

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

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

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

[0081] Using the ocean vertical deviation calculation method provided in this application, the residual geoid height of each GNSS-R specular reflection point in the ocean area is calculated based on the altimetry results, geoid height, and mean dynamic topography obtained from GNSS-R altimetry. A target grid is generated by dividing the global geographic region according to the target intervals of latitude and longitude. For each point in the target grid, the residual geoid height of that point is calculated using a weighted average based on multiple GNSS-R specular reflection points surrounding that point. The weights corresponding to the data from different signal sources at each GNSS-R specular reflection point are determined by consulting a GNSS-R altimetry accuracy table. Furthermore, the ocean vertical deviation is calculated using the residual geoid height and geoid height of each point, thus determining the ocean vertical deviation globally based on the spatial resolution corresponding to the target grid.

[0082] The ocean vertical deviation calculation method provided in this application takes into account the characteristics of the altimetry results of spaceborne GNSS-R measurement, which have diverse data sources and discontinuous GNSS-R mirror reflection point trajectories. It uses grid division and weighted averaging to calculate the ocean vertical deviation, which can more conveniently calculate the ocean vertical deviation results.

[0083] Furthermore, considering the differences in altimetry accuracy under different GNSS signal sources, incident angles, and sea surface significant wave heights, this application pre-constructs a GNSS-R altimetry accuracy table based on the altimetry accuracy of various GNSS signal sources for determining the weights of the weighted average. This achieves accurate weighting of data corresponding to different types of signal sources, further improving the accuracy of the marine vertical deviation calculation results for network points. Attached Figure Description

[0084] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0085] Figure 1 This is a flowchart of a GNSS-R ocean vertical deviation calculation method proposed in an embodiment of this application;

[0086] Figure 2 This is a diagram showing the distribution of GNSS-R mirror reflection points and the definition of the incident angle;

[0087] Figure 3 This is a schematic diagram of geoid height, mean dynamic topography, and GNSS-R sea level.

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

[0089] Figure 5 This is a schematic diagram of a GNSS-R marine vertical deviation calculation device proposed in one embodiment of this application;

[0090] Figure 6 This is a schematic diagram of an electronic device according to an embodiment of this application. Detailed Implementation

[0091] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0092] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0093] In the various embodiments of this application, it should be understood that the sequence number of each process described below does not imply 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 this application.

[0094] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects as detailed in this application.

[0095] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0096] Traditional sea surface altimetry relies on radar altimeters to actively transmit and receive signals. However, this method involves both transmitting and receiving devices, resulting in high costs. Furthermore, because traditional radar altimeters can only measure nadir points, rapid global coverage is difficult to achieve. GNSS-R interferometric altimetry, on the other hand, involves an observation satellite receiving GNSS signals reflected from the sea surface by different types of navigation satellites (signal sources) during its movement, thereby measuring the sea surface height at GNSS-R specular reflection points. The observation satellite can simultaneously receive multiple GNSS signals from various sources without transmitting signals, thus offering advantages such as wide coverage, low cost, easy network deployment, and facilitating rapid global coverage and revisiting.

[0097] However, the accuracy of sea surface height data products generated by GNSS-R interferometric altimetry is closely related to multiple factors such as the satellite incident angle, the type of navigation system of the signal source, and the effective wave height of the sea surface. Furthermore, the observation trajectory of sea surface height data products is closely related to the visibility duration of navigation satellites and cannot be continuous for a long period of time.

[0098] This application uses a gridded weighted average of data from multiple GNSS-R specular reflection points to calculate ocean vertical deviation, which can effectively improve the calculation efficiency of GNSS-R vertical deviation. By integrating multiple observation results from various GNSS signal sources, it can achieve accurate calculation of global ocean vertical deviation.

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

[0100] Figure 1 This is a flowchart illustrating a GNSS-R ocean vertical deviation calculation method proposed in one embodiment of this application. Figure 1 As shown, the method includes:

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

[0102] S2: Divide the global geographic region according to the target interval of latitude and longitude to generate a target grid;

[0103] S3: For any point in the target grid, select multiple GNSS-R specular reflection points around the point as target points;

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

[0105] S5: Calculate the corresponding ocean vertical deviation based on the residual geoid height and geoid height of each network point.

[0106] In this embodiment, the sea surface altimetry results of all GNSS-R specular reflection points measured by the observation satellite using the GNSS-R method in the global ocean region are first obtained, along with the geoid height and mean dynamic topography of each GNSS-R specular reflection point. Geoid height is the distance from the geoid along the normal to the Earth's ellipsoid. For the geoid height, this embodiment uses the EGM (Earth Gravitational Mode) reference model, obtained based on the latitude and longitude of the GNSS-R specular reflection points. Mean Dynamic Topography (MDT) is the difference between the multi-year mean sea surface height and the geoid, which can be obtained by calculating the multi-year mean sea surface height. In this embodiment, it is obtained based on the mean sea surface dynamic topography model, obtained based on the latitude and longitude of the GNSS-R specular reflection points. Based on the sea surface height (altimetry results), geoid height, and mean dynamic topography of the GNSS-R specular reflection points, the residual geoid height at each GNSS-R specular reflection point is calculated.

[0107] In this embodiment, the global geographical region is uniformly divided into latitude and longitude regions according to target intervals to generate a target grid. The vertical deviation of the global ocean region is obtained by calculating the ocean vertical deviation of all points in the target grid.

[0108] For each point in the target grid, multiple GNSS-R specular reflection points surrounding that point are taken as the corresponding target points. A weighted average is calculated based on the residual geoid heights of these target points to determine the residual geoid height at that point. Considering that the residual geoid heights at different GNSS-R specular reflection points may be calculated based on altimetry results from different signal sources, this embodiment pre-constructs a GNSS-R altimetry accuracy table based on the altimetry accuracy of GNSS-R altimetry results from different signal sources. When calculating the weighted average, the corresponding signal source's altimetry accuracy is determined by looking up the GNSS-R altimetry accuracy table according to the altimetry results of each target point, and then the weight corresponding to the residual geoid height is determined based on the altimetry accuracy. A weighted average is calculated based on the residual geoid heights of each target point and their corresponding weights to obtain the residual geoid height at that point.

[0109] Based on the latitude and longitude of each grid point, the geoid height of each point is obtained. Using both the geoid height and the residual geoid height, the ocean vertical deviation at each grid point is calculated, resulting in a 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 desired by the user. A smaller target interval results in a higher density of the target grid and a higher spatial resolution of the ocean vertical deviation, but also a greater computational load. Conversely, a larger target interval results in a lower density of the target grid, a lower spatial resolution of the ocean vertical deviation, and a less computational load.

[0110] In this embodiment, the method for calculating global ocean vertical deviation based on GNSS-R sea surface altimetry results employs a vertical deviation inversion algorithm suitable for the characteristics of GNSS-R data. Given the characteristics of GNSS-R, such as a large reflection area, rapid global coverage, high revisit frequency, and constantly changing incident angle and azimuth, a weighted average of data from multiple GNSS-R specular reflection points around the grid point is used instead of the traditional altimeter-based least squares method. This averaging of multiple measurement results effectively improves the accuracy and efficiency of calculating ocean vertical deviation.

[0111] Furthermore, this application considers the impact of different GNSS signal sources on altimetry accuracy when calculating the residual geoid height of network points. For example, the GNSS-R interferometric altimetry accuracy of BDS (BeiDou Navigation Satellite System), GPS (Global Positioning System), and GAL (Galileo satellite navigation system) varies due to differences in system bandwidth, incident angle, and significant sea wave height. Based on this, this embodiment constructs a GNSS-R altimetry accuracy table for different signal sources. By looking up the GNSS-R altimetry accuracy table for the corresponding signal source, the weight of the residual geoid height of the GNSS-R specular reflection point in the weighted average is determined, further improving the accuracy of ocean vertical deviation calculation.

[0112] As one embodiment of this application, the method of obtaining the height measurement results of multiple GNSS-R specular reflection points in an ocean area based on GNSS signals from an observation satellite includes:

[0113] Acquire sea surface height data products from GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points globally measured by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle;

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

[0115] Based on the actual observation area of ​​each GNSS-R specular reflection point, the height measurement results of GNSS-R specular reflection points whose actual observation area is not completely on the sea surface are removed 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 side lengths.

[0116] In one embodiment, the residual geoid height at the GNSS-R specular reflection point is calculated using multi-day sea level height measurements from a spaceborne GNSS-R, with geoid height obtained based on an Earth gravity model and mean sea level dynamic topography 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 Global Navigation Satellite System reflectance measurement technology) is first screened. Due to the large volume of related sea surface height data, to ensure the timeliness and accuracy of the calculation results, secondary sea surface height data products measured by GNSS-R within the target time range are selected, ensuring that the quality code of the data products is "good". The target time range can be set according to actual needs. To ensure the timeliness of the ocean vertical deviation calculation, a relatively close time range can be set as the target time range.

[0118] Figure 2 This is a diagram showing the distribution of GNSS-R specular reflection points and the definition of the incident angle. (For example...) Figure 2 As shown, the incident angles of the GNSS signals received by the observation satellite from different GNSS-R specular reflection points are ( Figure 2 The angle of incidence (α) is constantly changing. Considering that an excessively large incident angle will lead to a decrease in the accuracy of the altimeter measurement results, in order to ensure the accuracy of subsequent calculations of the ocean vertical deviation, the altimeter measurement data is pre-screened based on the incident angle. Sea surface height measurement results with an incident angle greater than a first threshold are removed, and altimeter measurement 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 altimeter measurement accuracy requirements, and this application does not impose any restrictions on it. Optionally, the first threshold can be set to 35°, that is, sea surface altimeter measurement data with α ≤ 35° are screened.

[0119] The sea surface height data product also includes reflection points on land and glaciers. To obtain the ocean vertical deviation for marine areas, it is necessary to filter out the altimeter results where the observation area is entirely above the sea surface. The actual observation area of ​​a GNSS-R mirror reflection point is a rectangular region. This rectangular region is an equivalent rectangular area centered on the GNSS-R mirror reflection point, with the directions intersecting the track and along the track as parallel to the sides of the rectangle, and the GNSS-R intersecting track spatial resolution and GNSS-R along the track spatial resolution as the side lengths. By checking whether the actual observation area of ​​each GNSS-R mirror reflection point is entirely above the sea surface, altimeter results with partially or completely non-overseas observation areas are eliminated, ultimately yielding altimeter results for GNSS-R mirror reflection points where the observation area is entirely above the sea surface.

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

[0121] As one embodiment of this application, the calculation of the residual geoid height at each GNSS-R specular reflection point includes:

[0122] Based on the Earth's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation.

[0123] Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation.

[0124] Based on the height measurement 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 mean sea surface dynamic topography (MDT) model and the Earth's gravity (EGM) model are obtained. Based on the EGM model and the latitude and longitude of the GNSS-R specular reflection point, the geoid height at that point is obtained using bilinear interpolation. Based on the MDT model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography at that point is obtained using bilinear interpolation.

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

[0127] h = N REF +ΔN+h MDT +ζ(t)+e.

[0128] Where h is the sea surface altimeter result of GNSS-R (direct observation data), that is, the distance from the GNSS-R specular reflection point to the reference ellipsoid; N REF Indicates the reference geoid; h MDT Let denot be the mean dynamic topography; ΔN represent the reference geoid residual; ζ(t) represent the time-varying sea surface topography; and e be the sea surface altimetry 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 topography, and GNSS-R sea level. (Example) Figure 3 As shown, the sea level height h is measured at the actual GNSS-R specular reflection point, while the mean dynamic topography and geoid height are auxiliary data obtained from the model. Based on the sea level height measurement results, geoid height, and mean dynamic topography at the GNSS-R specular reflection point, the "removal-recovery" method can be used to subtract the geoid height and mean dynamic topography from the sea level height measurement results to obtain the residual geoid height Δh at that point.

[0130] As one embodiment of this application, selecting multiple 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 selected as target points; the target spatial range is an area enclosed by a side length that is not less than half of the target interval at a distance of latitude and longitude from the network point.

[0132] In one embodiment, all GNSS-R specular reflection points within the target grid that are less than the distance to the grid point within the target spatial range are selected and used as the target points for that grid point. Specifically, the GNSS-R altimeter results are used to filter the data point by 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 satisfy the spatial requirements of a certain network point; Lat represents latitude, and Lon represents longitude; Sample i The corresponding spatial coordinates are (Lat i Lon i The target point.

[0135] The target spatial range is an area centered on a grid point and with target intervals defined by latitude and longitude boundaries. GNSS-R specular reflection points within this area serve as the target points for that grid point. The residual geoid height data of all target points are weighted and averaged to obtain the residual geoid height of that grid point. In other words, the residual geoid height data of GNSS-R specular reflection points over the oceans globally are mapped to each grid point of the target grid using a weighted average method, enabling accurate calculation of the residual geoid height at each grid point.

[0136] As one embodiment of this application, after selecting all GNSS-R specular reflection points around the network point that do not exceed the target space range as target points, the method further includes:

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

[0138] In one embodiment, the residual geoid height data of the target point can be further filtered 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 altimeter results are filtered point by point according to the following expression:

[0140]

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

[0142] As one embodiment of this application, before determining the weight of the residual geoid height of each target point based on the GNSS-R altimeter accuracy table, the method further includes:

[0143] Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on the altimeter results obtained by the observation satellite using GNSS signals emitted from different types of signal sources.

[0144] For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

[0145] In practical applications, GNSS-R sea surface height results involve more complex observation conditions. Besides the signal source affecting altimetry accuracy, the incident angle of the GNSS signal and different sea surface conditions also influence accuracy. For example, even with the same sea surface conditions, different incident angles will result in different error corrections and altimetry accuracy results; generally, a larger incident angle leads to a decrease in altimetry accuracy. Therefore, this embodiment comprehensively evaluates the impact of sea surface conditions and different incident angles and signal sources on the observation results. Based on altimetry data products from different signal sources and third-party external data sources, data analysis is performed on GNSS-R calibration comparison data to construct a two-dimensional lookup table for the altimetry accuracy of GNSS-R sea surface height products for each signal source, relating to the incident angle of the GNSS-R specular reflection point and the significant wave height of the sea surface—that is, the GNSS-R altimetry accuracy table. When calculating the residual geoid height of network points, the GNSS-R altimetry accuracy table for the corresponding signal source is consulted to achieve a reasonable weighting of the residual geoid height for each target point.

[0146] As one embodiment of this application, the weight of the residual geoid height of each target point is determined based on the GNSS-R altimeter accuracy table, and the residual geoid height of the network points is calculated by weighted average, including:

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

[0148] Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by looking up the GNSS-R altimetry accuracy table.

[0149] The weight of the corresponding residual geoid height is determined based on the altimetry accuracy.

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

[0151] In one embodiment, the incident angle and sea surface significant wave height corresponding to the altimeter results of target points surrounding the grid points in the target grid are obtained. Based on the incident angle and sea surface significant wave height, the altimeter accuracy is obtained by looking up the corresponding GNSS-R altimeter accuracy table for the signal source. Optionally, based on the obtained altimeter accuracy, the altimeter accuracy σ of each target point is obtained by a two-dimensional linear interpolation method. i .

[0152] Furthermore, based on the obtained altimetry accuracy, the weight corresponding to the residual geoid height of the target point is determined and used to calculate the weighted average of data from multiple target points. Based on the residual geoid heights of all target points corresponding to the network point, the corresponding residual geoid height ΔH is calculated:

[0153]

[0154] Where, Δh i Let σ be the residual geoid height value of the i-th target point. i This is an estimate of the sea surface height measurement error (height measurement accuracy) for the i-th target point.

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

[0156] As one embodiment of this application, based on the residual geoid height and geoid height of each network point, the corresponding ocean vertical deviation is calculated, including:

[0157] Based on the residual geoid height of the network points, calculate the residual vertical deviation;

[0158] Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation.

[0159] Based on the geoid height of the network points, the vertical deviation of the model is calculated.

[0160] Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

[0161] In one embodiment, the residual vertical deviation is calculated based on the residual geoid height of the grid points, and the model vertical deviation is calculated based on the geoid height of each grid point in the target grid. Figure 4 This is a schematic diagram for calculating the deviation of the ocean vertical. For example... Figure 4 As shown, let the components of the vertical deviation θ in the meridian plane and the east-west plane be: ζ res and η res Then, based on the distance dS between two adjacent grid points P and P1 on the target grid, calculate the two components ξ of the vertical deviation in the meridian plane and the east-west plane, respectively. res and η res :

[0162]

[0163]

[0164] in, dN λ These represent the residual geoid height differences between two adjacent grid points P and P1 on the meridian and east-west planes of the target grid, respectively. dSλ These represent the distances between two adjacent grid points P and P1 on the meridian plane and the east-west plane of the target grid, respectively; R is the Earth's radius. dλ represents the difference in latitude and longitude between two adjacent grid points P and P1 on the meridian and lateral planes of the target grid.

[0165] Similarly, based on the EGM Earth gravity model and the latitude and longitude of the network points, the reference geoid height of the network points is calculated using bilinear interpolation. Based on the geoid height, the two components ξ of the corresponding model vertical deviation in the meridian and zonal planes are calculated. model and η model .

[0166] Finally, using the "remove-restore" method, the two components ξ and η of the calculated ocean vertical deviation in the meridional and trochanteric planes are recovered, and the ocean vertical deviation of this point is obtained:

[0167] ξ=ξ model +ξ res ;

[0168] η = η model +η res .

[0169] As one embodiment of this application, after calculating the average residual geoid height of the network points, the method further includes:

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

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

[0172] Based on the sparsity factor, a new target grid is generated on the basis of the old target grid.

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

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

[0175] In one embodiment, when the target interval is expanded, a new target grid is obtained by sparsening based on the old target grid. The residual geoid height of each point on the new target grid is calculated based on the residual geoid height of each point on the old target grid. First, the required sparsity factor 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 sparsed to a 20′ grid or a 1° grid, the corresponding sparsity factor is determined.

[0176] Then, based on the sparsity factor, a 20′ grid or a 1° grid is obtained from the 5′ grid. Using the residual geoid height data of each point in the 5′ grid, the residual geoid height of each point in the 20′ or 1° grid is calculated using an inverse distance weighting method. Simultaneously, according to the EGM reference model, the model geoid height of the 20′ or 1° grid is determined by bilinear interpolation. Based on the residual geoid height of the 20′ or 1° grid and the model geoid height, the corresponding ocean vertical deviation is calculated.

[0177] In this embodiment, when the spacing between adjacent points in the target grid changes, the residual geoid height of the points in the new grid is calculated by weighted averaging based on the data of each point in the current grid (old grid) according to the sparsity factor between the new and old grids. This eliminates the need for steps such as re-screening the target points in the new grid, determining the height accuracy and weighting, and calculating the weighted average, thus saving computational resources and improving computational efficiency.

[0178] As one embodiment of this 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 target interval is determined based on 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 specular reflection point on the sea surface, thus generating a basic grid. 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 sparsed according to user needs, and multiple ocean vertical deviation data products with lower spatial resolutions can be quickly calculated based on this ocean vertical deviation data product with the highest spatial resolution. This eliminates the need for re-selecting target points and performing weighted average calculations, saving computational resources and improving the efficiency of ocean vertical deviation calculation.

[0180] For example, the target interval of the basic grid is 2.5′. The grid is further sparsed 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 by using the inverse distance weighting method. Then, the ocean vertical deviation is calculated to obtain a low-resolution ocean vertical deviation data product.

[0181] Based on the same inventive concept, one embodiment of this application provides a GNSS-R marine vertical deviation calculation device. (Reference) Figure 5 , Figure 5 This is a schematic diagram of a GNSS-R marine vertical deviation calculation device 100 according to an embodiment of this application. Figure 5 As shown, the device includes:

[0182] The preprocessing module 101 is configured to acquire the GNSS-R altimeter results, geoid height and mean dynamic topography of each GNSS-R specular reflection point in the marine area, and to calculate the residual geoid height of each GNSS-R specular reflection point.

[0183] The grid generation module 102 is configured to divide the global geographic region according to the target interval of latitude and longitude, and generate the target grid.

[0184] The grid filtering module 103 is configured to, for any point in the target grid, filter multiple GNSS-R specular reflection points around the point as target points;

[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 altimeter accuracy table, and calculate the residual geoid height of the network points by weighted averaging; the GNSS-R altimeter accuracy table is constructed based on the altimeter accuracy of different GNSS signal sources under different incident angles and sea surface significant wave height conditions; based on the residual geoid height and geoid height of each network point, the corresponding ocean vertical deviation is calculated.

[0186] In one embodiment of this application, the preprocessing module 101 includes:

[0187] The acquisition submodule is configured to acquire sea surface height data products from GNSS-R altimetry measurements; 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 filtering submodule is configured to, based on a first threshold, remove sea surface height measurement results from the sea surface height data product whose incident angle is greater than the first threshold; and based on the actual observation area of ​​each GNSS-R specular reflection point, remove height measurement results from the sea surface height data product for GNSS-R specular 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] In one embodiment of this application, the preprocessing module 101 further includes a first calculation submodule, configured to perform the following steps:

[0190] Based on the Earth's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation.

[0191] Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation.

[0192] Based on the height measurement 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 one embodiment of this application, the grid filtering module 103 is specifically configured to filter out all GNSS-R specular 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 that is not less than half of the target interval in latitude and longitude from the grid point.

[0194] As one embodiment of this application, after selecting all GNSS-R specular reflection points around the grid points that do not exceed the target space range as target points, the grid filtering 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 selected.

[0196] In one embodiment of this application, the apparatus further includes a construction module configured to perform the following steps:

[0197] Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on the altimeter results obtained by the observation satellite using GNSS signals emitted from different types of signal sources.

[0198] For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

[0199] In one embodiment of this application, the calculation module 104 is configured to determine the weights of the residual geoid height of each target point based on the GNSS-R altimeter accuracy table, and calculate the residual geoid height of the network points by weighted average, specifically including:

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

[0201] Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by looking up the GNSS-R altimetry accuracy table.

[0202] The weight of the corresponding residual geoid height is determined based on the altimetry accuracy.

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

[0204] As one embodiment of this application, the calculation module 104 is configured to calculate the corresponding ocean vertical deviation based on the residual geoid height and geoid height of each network point, including:

[0205] Based on the residual geoid height of the network points, calculate the residual vertical deviation;

[0206] Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation.

[0207] Based on the geoid height of the network points, the vertical deviation of the model is calculated.

[0208] Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

[0209] In one embodiment of this application, after calculating the average residual geoid height of the network points, the calculation module 104 is further configured to perform the following steps:

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

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

[0212] Based on the sparsity factor, a new target grid is generated on the basis of the old target grid.

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

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

[0215] Based on the same inventive concept, one embodiment of this application provides a readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the ocean vertical deviation calculation method as described in any of the above embodiments of this application.

[0216] Based on the same inventive concept, one embodiment of this application provides an electronic device, with reference to... Figure 6 , Figure 6 This is a schematic diagram of an electronic device according to an embodiment of this application. The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When executed by the processor, the computer program implements the steps in the GNSS-R marine vertical deviation calculation method as described in any of the above embodiments of this application.

[0217] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

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

[0219] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to this application.

[0220] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, embodiments of this application can take the form of computer program products 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 code.

[0221] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0222] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The 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 equipment, causing a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0224] Although preferred embodiments of the embodiments of this application have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, this application is to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of this application.

[0225] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0226] The above provides a detailed description of the GNSS-R marine vertical deviation calculation method, apparatus, equipment, and storage medium provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for calculating the vertical deviation of a GNSS-R ocean line, characterized in that, include: Obtain the height measurement results, geoid height and mean dynamic topography of each GNSS-R mirror reflection point in the marine area, and calculate the residual geoid height of each GNSS-R mirror reflection point; The global geographic region is divided according to the target intervals of latitude and longitude, generating a target grid; For any point in the target grid, select multiple GNSS-R specular reflection points around the point as target points; The weights of the residual geoid heights of each target point are determined based on the GNSS-R altimeter accuracy table, and the residual geoid heights of the network points are calculated by weighted averaging. The GNSS-R altimeter accuracy table is constructed based on the altimeter accuracy of different GNSS signal sources under different incident angles and sea surface significant wave height conditions; Based on the residual geoid height and geoid height at each network point, calculate the corresponding ocean vertical deviation; If the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval. Determine the sparsity factor based on the new target interval; Based on the sparsity factor, a new target grid is generated on the basis of the old target grid. Based on the residual geoid height of each point in the old target grid, the residual geoid height of each point in the new target grid is calculated by inverse distance weighting. The geoid height in the new target grid is determined based on the Earth's gravity model and bilinear interpolation. Based on the residual geoid height and geoid height of each point in the new target grid, the corresponding ocean vertical deviation is calculated. This ocean vertical deviation is obtained by adding the residual vertical deviation and the model vertical deviation in the new target grid. The residual vertical deviation in the new target grid is based on the residual geoid height, and the model vertical deviation in the new target grid is based on the geoid height. The method of determining the weights of the residual geoid height for each target point based on the GNSS-R altimeter accuracy table, and calculating the residual geoid height of the network points by weighted averaging, includes: Obtain the incident angle and significant wave height of the sea surface corresponding to the altimetry results of each target point; Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by consulting the GNSS-R altimetry accuracy table. The weight of the corresponding residual geoid height is determined based on the altimetry accuracy. Based on the residual geoid height and corresponding weight of each target point, the residual geoid height of the network points is calculated by weighted average.

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 specular reflection points in the ocean region based on GNSS signals from observation satellites, including: Acquire sea surface height data products from GNSS-R altimetry; the sea surface height data products include: altimetry results of all GNSS-R specular reflection points globally measured by observation satellites based on GNSS signals; each altimetry result has a corresponding incident angle; Based on a first threshold, sea surface height measurement results with an incident angle greater than the first threshold are removed from the sea surface height data product; Based on the actual observation area of ​​each GNSS-R specular reflection point, the height measurement results of GNSS-R specular reflection points whose actual observation area is not completely on the sea surface are removed 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 side lengths.

3. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that, Calculate the residual geoid height at each GNSS-R mirror reflection point, including: Based on the Earth's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation. Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation. Based on the height measurement 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, Select multiple GNSS-R specular reflection points around the grid 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 selected as target points; the target spatial range is an area enclosed by a side length that is not less than half of the target interval at a distance of latitude and longitude from the network point.

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

6. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that, Before determining the weights of the residual geoid height for each target point based on the GNSS-R altimeter accuracy table, the following steps are also included: Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on GNSS signals transmitted by observation satellites from different types of signal sources. For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

7. The GNSS-R ocean vertical deviation calculation method according to claim 1, characterized in that, Based on the residual geoid height and geoid height at each network point, the corresponding ocean vertical deviation is calculated, including: Based on the residual geoid height of the network points, calculate the residual vertical deviation; Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation. Based on the geoid height of the network points, the vertical deviation of the model is calculated. Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

8. 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.

9. A GNSS-R ocean vertical deviation calculation device, characterized in that, include: The preprocessing module is configured to acquire the GNSS-R altimeter results, geoid height, and mean dynamic topography of each GNSS-R specular reflection point in the marine area, and to calculate the residual geoid height of each GNSS-R specular reflection point. The grid generation module is configured to divide global geographic regions according to target intervals of latitude and longitude, and generate target grids; The grid filtering module is configured to, for any point in the target grid, filter multiple GNSS-R specular reflection points around the point as target points; The calculation module is configured to determine the weight of the residual geoid height of each target point based on the GNSS-R altimeter accuracy table, and calculate the residual geoid height of the network points by weighted average. The GNSS-R altimeter accuracy table is constructed based on the altimeter accuracy of different GNSS signal sources under different incident angles and sea surface significant wave heights; the corresponding ocean vertical deviation is calculated based on the residual geoid height and geoid height of each network point. The calculation module is configured to determine the weights of the residual geoid height for each target point based on the GNSS-R altimeter accuracy table, and calculate the residual geoid height of the network points by weighted averaging, specifically including: Obtain the incident angle and significant wave height of the sea surface corresponding to the altimetry results of each target point; Based on the incident angle and the sea surface significant wave height, the corresponding altimetry accuracy is obtained by consulting the GNSS-R altimetry accuracy table. The weight of the corresponding residual geoid height is determined based on the altimetry accuracy. Based on the residual geoid height and corresponding weight of each target point, the residual geoid height of the network points is calculated by weighted average. The computing module is also configured to perform the following steps: If the target interval changes, a new target interval is obtained; the new target interval is greater than the old target interval. Determine the sparsity factor based on the new target interval; Based on the sparsity factor, a new target grid is generated on the basis of the old target grid. Based on the residual geoid height of each point in the old target grid, the residual geoid height of each point in the new target grid is calculated by inverse distance weighting. The geoid height in the new target grid is determined based on the Earth's gravity model and bilinear interpolation. Based on the residual geoid height and geoid height of each point in the new target grid, the corresponding ocean vertical deviation is calculated. The ocean vertical deviation is obtained by adding the residual vertical deviation and the model vertical deviation in the new target grid. The residual vertical deviation in the new target grid is obtained based on the residual geoid height in the new target grid. The model vertical deviation in the new target grid is obtained based on the geoid height in the new target grid.

10. The GNSS-R marine vertical deviation calculation device according to claim 9, characterized in that, The preprocessing module includes: The acquisition submodule is configured to acquire sea surface height data products from GNSS-R altimetry measurements; 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 filtering submodule is configured to, based on a first threshold, remove sea surface height measurement results from the sea surface height data product whose incident angle is greater than the first threshold; and based on the actual observation area of ​​each GNSS-R specular reflection point, remove height measurement results from the sea surface height data product for GNSS-R specular 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.

11. The GNSS-R marine vertical deviation calculation device according to claim 9, characterized in that, The preprocessing module further includes a first calculation submodule, configured to perform the following steps: Based on the Earth's gravity model and the latitude and longitude of the GNSS-R mirror reflection point, the geoid height of the GNSS-R mirror reflection point is calculated by bilinear interpolation. Based on the mean sea surface dynamic topography model and the latitude and longitude of the GNSS-R specular reflection point, the mean dynamic topography of the GNSS-R specular reflection point is calculated by bilinear interpolation. Based on the height measurement 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.

12. The GNSS-R marine vertical deviation calculation device according to claim 9, characterized in that, The grid filtering module is specifically configured to filter 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 spatial range is an area enclosed by a side length that is not less than half the target interval at a distance of latitude and longitude from the network point.

13. The GNSS-R marine vertical deviation calculation device according to claim 12, 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 filtering 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 selected.

14. The GNSS-R marine vertical deviation calculation device according to claim 9, characterized in that, The device also includes a construction module configured to perform the following steps: Globally, the altimeter accuracy, incident angle, and significant sea wave height are calculated based on GNSS signals transmitted by observation satellites from different types of signal sources. For each type of signal source, a two-dimensional GNSS-R altimeter accuracy table is constructed based on the variation law of altimeter accuracy of the corresponding altimeter results with the incident angle and the significant wave height of the sea surface. Each combination of incident angle and significant wave height in the GNSS-R altimeter accuracy table corresponds to a unique altimeter accuracy.

15. The GNSS-R marine vertical deviation calculation device according to claim 9, characterized in that, The calculation module is configured to calculate the corresponding ocean vertical deviation based on the residual geoid height and geoid height at each network point, including: Based on the residual geoid height of the network points, calculate the residual vertical deviation; Based on the Earth's gravity model and the latitude and longitude of the network points, the geoid height of the network points is calculated using bilinear interpolation. Based on the geoid height of the network points, the vertical deviation of the model is calculated. Based on the residual vertical deviation and the model vertical deviation, the ocean vertical deviation of the network points is calculated.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1-8.

17. 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, it implements the steps in the method as described in any one of claims 1-8.

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