A system and method for calculating vertical deviation on-orbit based on radar altimeter formation measurement

Abstract

The present application provides an on-orbit solution system and method for vertical deviation based on radar altimeter formation measurement. The system reads the altitude data of the formation measurement satellite radar altimeter and removes abnormal values; performs strip matching on the sea surface height data of the adjacent tracks of the satellite radar altimeter formation flight; selects the effective sea surface height data for solving the vertical deviation of the corresponding strip from the on-orbit sea surface height data of the matched satellite radar altimeter formation; performs differential processing on the effective sea surface height data, calculates the sea surface height slope data after eliminating the gross errors; determines whether the formation measurement crosses the track direction, and if so, selects the cross-track slope and calculates the accuracy of the cross-track sea surface height slope; if not, selects the along-track slope and calculates the accuracy of the along-track sea surface height slope; based on the least squares principle, solves the north-south component and the east-west component of the vertical deviation of the strip. The advantage of the present application is that it can quickly solve the north-south component and the east-west component of the vertical deviation with high resolution on-orbit.

Description

Technical Field

[0001] The present application belongs to the field of ocean remote sensing mapping, and specifically relates to an on-orbit vertical deviation solution system and method based on radar altimeter formation measurement. Background Art

[0002] Radar altimeter is an important active microwave remote sensor, which is carried on ocean remote sensing satellites. It transmits radar pulse signals to the sea surface and receives echo signals to obtain ocean observation data such as sea surface height (SSH), effective wave height, and wind speed. Gravity-related parameters such as ocean geoid and vertical deviation can be extracted from the sea surface height data of the satellite altimeter, and the ocean gravity field can be further inverted. Satellite altimeter has a rapid global coverage capability and can obtain global ocean gravity field information from space on a large scale, greatly improving the breadth and depth of human understanding of the ocean. Compared with traditional gravity detection methods (such as ship measurement and airborne), satellite altimeter technology can complete the workload of the past century in a few months; compared with gravity satellites, satellite altimeter can obtain high-resolution ocean gravity fields on a global scale. Therefore, satellite radar altimeter has become the most effective means to build a high-precision and high-resolution global ocean gravity field model.

[0003] In order to achieve higher accuracy (such as milligal level) and higher resolution (such as true 1'×1') global ocean gravity field detection, some experts have proposed a radar altimeter satellite formation measurement mode. The vertical deviation method is currently the most commonly used method for satellite altimeter to invert the ocean gravity field. The vertical deviation is defined as the gradient of the geoid height, and is usually calculated approximately using the slope of the sea surface height, usually expressed as a north-south component and an east-west component. Through radar altimeter satellite formation flight measurement, the along-track and cross-track slope information of the sea level at the sub-satellite point can be obtained simultaneously, and high-resolution sea surface height slope measurement can be achieved in most of the world's oceans in a relatively short time, providing high-resolution vertical deviation data for the accurate determination of the ocean gravity field. However, the existing technologies all require a large amount of satellite altimeter data to be accumulated in order to solve the high-resolution vertical deviation. There is no method for quickly solving the high-resolution strip vertical deviation on-orbit for radar altimeter formation measurement data. At present, there is still a lack of an on-orbit solution method for vertical deviation based on radar altimeter formation measurement. Summary of the invention

[0004] The purpose of this application is to overcome the defect that the prior art cannot quickly calculate the vertical line deviation on track.

[0005] In order to achieve the above-mentioned purpose, the present application proposes an on-orbit vertical deviation solution system based on radar altimeter formation measurement, the system comprising:

[0006] Sea surface height data screening module: used to perform strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flight, and screen out the effective sea surface height data for solving the strip vertical deviation from the matched satellite radar altimeter formation sea surface height data;

[0007] Sea surface height slope calculation module: used to perform differential processing on the screened effective sea surface height data, and calculate the sea surface height slope data after eliminating the gross errors;

[0008] Along-track accuracy calculation module: used to select the along-track slope from the sea surface high slope data, and calculate the along-track sea surface high slope accuracy according to the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points;

[0009] Cross-track accuracy calculation module: used to select the cross-track slope from the sea surface high slope data, and calculate the cross-track sea surface high slope accuracy based on the sea surface high accuracy of two adjacent points used to calculate the cross-track sea surface high slope and the distance between the two adjacent points, as well as the relative orbit determination accuracy of the satellite formation; and

[0010] Vertical deviation component calculation module: It is used to calculate the north-south component and east-west component of the vertical deviation of the strip based on the least squares principle, using the sea surface high slope data and its corresponding along / cross track sea surface high slope accuracy.

[0011] As an improvement of the above system, the processing process of the sea level height data screening module includes:

[0012] Step A1: performing strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flying according to the satellite cycle number, arc segment number and observation time information;

[0013] Step A2: According to the ground track position of the satellite radar altimeter formation strip and the set search distance, the valid sea surface height data for solving the vertical deviation of the corresponding strip are screened out from the sea surface height data of the matching satellite radar altimeter formation; when screening, the data within the set radius centered on the subsatellite point of the strip is the valid data.

[0014] As an improvement of the above system, the processing process of the sea surface high slope calculation module includes:

[0015] Step B1: Calculate the time difference Δt, longitude difference Δλ, and latitude difference between two adjacent points based on the sea surface height data of the formation satellite radar altimeter and the sea surface height difference Δh, and calculate the spherical distance d between two adjacent points ij ; Point i and point j are two adjacent points:

[0016] Δt=t j -t j

[0017] Δλ=λ j -λ i

[0018]

[0019] Δh=h j -h i

[0020]

[0021] Among them, t i , t j ,λ i ,λ j , h j ,h i Represent the time, longitude, latitude and sea level of two adjacent points respectively; Re is the average radius of the earth;

[0022] Step B2: According to the time difference and distance between two adjacent points, the abnormal sea surface height difference caused by the sub-satellite point of the track passing through the land or island is eliminated, and the sea surface height difference beyond the reasonable range is eliminated;

[0023] Step B3: Calculate the time t of the sea surface high slope using the height measurement data after eliminating gross errors dov , longitude λ dov ,latitude Slope ε dov and azimuth az dov ;

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] In the formula, is the average latitude of two adjacent points,

[0030] As an improvement of the above system, the processing process of the along-track accuracy calculation module includes:

[0031] Step C1: Select the along-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is less than the threshold set according to the satellite altimeter sampling interval and the time difference between the formation satellites, it is along-track;

[0032] Step C2: Calculate the sea surface height accuracy σ along the track according to the sea surface height accuracy of two adjacent points used to calculate the sea surface height slope along the track and the distance between the two adjacent points. dov ;

[0033]

[0034] in, Respectively represent the accuracy of two adjacent points.

[0035] As an improvement of the above system, the processing process of the cross-track accuracy calculation module includes:

[0036] Step D1: Select the cross-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is greater than the threshold set according to the satellite altimeter sampling interval and the time difference between the formation satellites, it is the cross-track direction;

[0037] Step D2: Calculate the cross-track sea surface height slope accuracy σ based on the sea surface height accuracy of two adjacent points used to calculate the cross-track sea surface height slope, the distance between the two adjacent points, and the relative orbit determination accuracy of the satellite formation. dov ;

[0038]

[0039] in, Respectively represent the accuracy of two adjacent points; σ rorb Indicates the relative orbit determination accuracy of the satellite formation.

[0040] As an improvement of the above system, the processing process of the vertical deviation component solving module includes:

[0041] Step E1: Calculate the respective weighting factors of the sea surface high slope used to solve the vertical deviation component according to the accuracy value of the sea surface high slope along / cross track and the distance to the point to be calculated;

[0042] The weight P of the sea surface height slope at the kth observation point k Set to:

[0043]

[0044] or

[0045]

[0046] Among them, d k is the distance from the sea surface high slope of the kth observation point to the point to be calculated; σ i is the standard deviation of the sea surface height slope at the kth observation point;

[0047] Step E2: using the sea surface high slope data along / cross track for solving the vertical deviation component and their respective weighting factors, solve the north-south component and east-west component of the vertical deviation of the strip based on the least square method;

[0048] The observation equation for the average value of the sea surface high slope and vertical deviation component along / cross track is:

[0049]

[0050] Among them, ε k 、v k and α k are the sea surface high slope along / cross track, residual and azimuth of the hth observation point respectively; n is the number of sea surface high slope observation points along / cross track; and is the average of the north-south component and the east-west component of the point;

[0051] According to the basic principle of least squares:

[0052]

[0053] Calculate the average value of the north-south component and the east-west component of the vertical deviation on the grid and

[0054] The present application also provides an on-orbit calculation method for vertical deviation based on radar altimeter formation measurement, which is implemented based on the above system and includes:

[0055] Step 1) read the altimetry data of the formation measurement satellite radar altimeter, edit the data and remove abnormal values ​​in the altimetry data;

[0056] Step 2) performing strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flying according to the satellite cycle number, arc segment number and observation time information;

[0057] Step 3) according to the ground track position of the satellite radar altimeter formation strip and the set search distance, the effective sea surface height data for solving the vertical deviation of the corresponding strip is screened out from the sea surface height data of the matching satellite radar altimeter formation;

[0058] Step 4) performing differential processing on the screened effective sea surface height data, and calculating the sea surface height slope data after eliminating the gross errors;

[0059] Step 5) According to the time difference between two adjacent points used to calculate the sea surface high slope, determine whether the formation measures the cross-track direction. If so, select the cross-track direction slope in the sea surface high slope data, and calculate the cross-track direction sea surface high slope accuracy according to the sea surface high accuracy of the two adjacent points used to calculate the cross-track direction sea surface high slope and the distance between the two adjacent points and the relative orbit determination accuracy of the satellite formation;

[0060] If not, the along-track slope in the sea surface high slope data is selected, and the along-track sea surface high slope accuracy is calculated according to the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points;

[0061] Step 6) The sea surface high slope data and its corresponding along / cross track sea surface high slope accuracy are used to solve the north-south component and east-west component of the vertical line deviation of the strip based on the least squares principle.

[0062] Compared with the prior art, the advantages of this application are:

[0063] 1. By performing slope processing on the along-track and cross-track sea surface height data measured by the satellite radar altimeter formation, high-resolution north-south and east-west component information of vertical deviation can be extracted simultaneously;

[0064] 2. By simultaneously calculating the along-track and cross-track slopes of the on-orbit sea surface height data measured by the satellite radar altimeter formation, the solution speed is greatly accelerated, and high-resolution strip vertical deviation solution can be achieved in most sea areas in the world in a relatively short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 The figure shows the structure of the on-orbit vertical deviation solution system based on radar altimeter formation measurement;

[0066] Figure 2 Shown is a flow chart of the on-orbit solution method of vertical deviation based on radar altimeter formation measurement. DETAILED DESCRIPTION

[0067] The technical solution of the present application is described in detail below with reference to the accompanying drawings.

[0068] The on-orbit solution system and method of vertical deviation based on radar altimeter formation measurement proposed in the present application is not only used in dual-satellite formations, but also applicable to other multi-satellite formations. By simultaneously calculating the along-track and cross-track slopes of the on-orbit sea surface height data measured by the satellite radar altimeter formation, the solution speed is greatly accelerated, and high-resolution strip vertical deviation solution can be achieved in most sea areas in the world in a relatively short time.

[0069] Example 1

[0070] like Figure 1As shown, the present application proposes an on-track solution system for vertical deviation based on radar altimeter formation measurement, including a sea surface height data screening module, a sea surface height slope calculation module, an along-track accuracy calculation module, a cross-track accuracy calculation module and a vertical deviation component solution module.

[0071] The design of each module is as follows:

[0072] 1. Sea surface height data screening module: used to perform strip matching on the sea surface height data (time, longitude, latitude, sea surface height) of adjacent tracks of satellite radar altimeter formation flight, and screen out the valid sea surface height data for solving the strip vertical deviation from the matched satellite radar altimeter formation sea surface height data;

[0073] The processing of the sea surface height data screening module includes:

[0074] Step 1: Formation strip matching: Use the satellite cycle number, arc segment number, observation time and other spatiotemporal information to perform strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flight;

[0075] Step 2: Filter valid data; According to the ground track position of the satellite radar altimeter formation strip and the set search distance, filter out the valid sea surface height data for solving the corresponding strip vertical deviation from the sea surface height data of the matching satellite radar altimeter formation. When screening, the valid data is within the set radius with the strip subsatellite point as the center.

[0076] 2. Sea surface height and slope calculation module: used to perform differential processing on the sea surface height data (time, longitude, latitude, sea surface height) of the formation satellite altimeter obtained by screening, and calculate the sea surface height and slope information (time, longitude, latitude, slope, azimuth) after eliminating the gross errors;

[0077] The processing of the sea surface high slope calculation module includes:

[0078] Step 1: Differential processing: Calculate the time difference Δt, longitude difference Δλ, latitude difference Δλ between two adjacent points based on the sea surface height data (time, longitude, latitude, sea surface height) of the formation satellite radar altimeter. and the sea surface height difference Δh, and calculate the spherical distance d between two adjacent points (point i and point j) ij ;

[0079] Δt=t j -t i

[0080] Δλ=λ j -λ i

[0081]

[0082] Δh=hj -h i

[0083]

[0084] Where, t i , t j ,λ i ,λ j , h j ,h i They respectively represent the time, longitude, latitude and sea level height of two adjacent points; Re is the average radius of the earth.

[0085] Step 2: Eliminate gross errors: According to the time difference and distance between two adjacent points, eliminate the abnormal sea surface height difference caused by the sub-satellite point of the track passing through land and islands, and eliminate the sea surface height difference that exceeds the reasonable range;

[0086] Step 3: Calculate the sea surface high slope; use the altimetry data after eliminating gross errors to calculate the time, longitude, latitude, slope and azimuth of the sea surface high slope;

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] In the formula, is the average latitude of two adjacent points,

[0093] 3. Along-track accuracy calculation module: used to select the along-track slope from the sea surface high slope data of the satellite altimeter formation, and calculate the along-track sea surface high slope accuracy based on the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points;

[0094] The processing of the along-track accuracy calculation module includes:

[0095] Step 1: Select the along-track slope data; select the along-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is less than a reasonable threshold set according to the satellite altimeter sampling interval and the time difference between formation satellites, it is along-track; otherwise, it is cross-track.

[0096] Step 2: Calculate the along-track slope accuracy; Calculate the along-track sea surface height slope accuracy based on the sea surface height accuracy of two adjacent points used to calculate the along-track sea surface height slope and the distance between the two adjacent points;

[0097]

[0098] In the formula, Respectively represent the accuracy of two adjacent points. ( This can be a fixed value assigned by an external evaluation or calculated based on altimeter data).

[0099] 4. Cross-track accuracy calculation module: used to select the cross-track slope from the sea surface high slope data of the satellite altimeter formation, and calculate the cross-track sea surface high slope accuracy based on the sea surface high accuracy of two adjacent points used to calculate the cross-track sea surface high slope and the distance between the two adjacent points and the relative orbit determination accuracy of the satellite formation;

[0100] The processing of the cross-track accuracy calculation module includes:

[0101] Step 1: Select the cross-track slope data; select the cross-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is less than a reasonable threshold set according to the satellite altimeter sampling interval and the time difference between formation satellites, it is along-track; otherwise, it is cross-track.

[0102] Step 2: Calculate the cross-track slope accuracy; Calculate the cross-track sea surface height slope accuracy based on the sea surface height accuracy of two adjacent points used to calculate the cross-track sea surface height slope and the distance between the two adjacent points and the relative orbit determination accuracy of the satellite formation;

[0103]

[0104] In the formula, Respectively represent the accuracy of two adjacent points, σ rorb Indicates the relative orbit determination accuracy of the satellite formation. This can be a fixed value assigned by external evaluation or calculated based on altimeter data);

[0105] 5. Vertical deviation component calculation module: It is used to calculate the north-south component and east-west component of the vertical deviation of the strip based on the sea surface high slope data (time, longitude, latitude, slope, azimuth) and its corresponding along / cross track sea surface high slope accuracy.

[0106] The processing of the vertical deviation component solution module includes:

[0107] Step 1: Calculate weighting factors: Calculate the weighting factors of the sea surface high slopes used to solve the vertical deviation components according to the accuracy of the sea surface high slopes along / cross track and the distance to the point to be calculated.

[0108] The weight P of the sea surface height slope at the kth observation point k Set to:

[0109]

[0110] or

[0111]

[0112] Where, d k is the distance from the sea surface high slope of the hth observation point to the point to be calculated; σ k is the standard deviation of the sea surface height slope at the kth observation point.

[0113] Step 2: Least squares solution: The along / cross-track sea surface high slope data and their respective weighting factors of the vertical deviation components are used to solve the north-south component and east-west component of the vertical deviation of the strip based on the least squares method.

[0114] If there are n along-track / cross-track sea surface high slope data within a certain sea area near the satellite formation strip to be calculated, then the observation equation for the average value of the along-track / cross-track sea surface high slope and the vertical deviation component is:

[0115]

[0116] In the formula, ε k 、v k and α k are the sea surface high slope along / cross track, residual and azimuth of the kth observation point respectively; n is the number of sea surface high slope observation points along / cross track; and It is the average of the north-south component and the east-west component of the point.

[0117] According to the basic principle of least squares:

[0118]

[0119] Calculate the average value of the north-south component and the east-west component of the vertical deviation on the grid and

[0120] Example 2

[0121] like Figure 2 As shown, the present application also proposes an on-orbit solution method for vertical deviation based on radar altimeter formation measurement, which is implemented based on the above system and includes:

[0122] Step 1) read the altimetry data of the formation measurement satellite radar altimeter, edit the data and remove abnormal values ​​in the altimetry data;

[0123] Step 2) performing strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flying by using the space-time information such as satellite cycle number, arc segment number and observation time;

[0124] Step 3) according to the ground track position of the satellite radar altimeter formation strip and the set search distance, the effective sea surface height data for solving the vertical deviation of the corresponding strip is screened out from the sea surface height data of the matching satellite radar altimeter formation;

[0125] Step 4) performing differential processing on the sea surface height data (time, longitude, latitude, sea surface height) of the screened satellite altimeter formation, and calculating the sea surface height slope information (time, longitude, latitude, slope, azimuth) after eliminating gross errors;

[0126] Step 5) judging whether the formation measures the cross-track direction according to the time difference between two adjacent points used to calculate the sea surface high slope, and if so, selecting the cross-track direction slope in the sea surface high slope data of the satellite altimeter formation, and calculating the cross-track direction sea surface high slope accuracy according to the sea surface high accuracy of the two adjacent points used to calculate the cross-track direction sea surface high slope and the distance between the two adjacent points and the relative orbit determination accuracy of the satellite formation;

[0127] If not, the along-track slope in the sea surface high slope data of the satellite altimeter formation is selected, and the along-track sea surface high slope accuracy is calculated according to the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points;

[0128] Step 6) The sea surface high slope data (time, longitude, latitude, slope, azimuth) and its corresponding along / cross track sea surface high slope accuracy are solved based on the least squares principle to obtain the north-south component and east-west component of the vertical deviation of the strip.

[0129] The present application may also provide a computer device, comprising: at least one processor, a memory, at least one network interface and a user interface. The various components in the device are coupled together through a bus system. It is understood that the bus system is used to achieve connection and communication between these components. In addition to the data bus, the bus system also includes a power bus, a control bus and a status signal bus.

[0130] The user interface may include a display, a keyboard or a pointing device, such as a mouse, a trackball, a touch pad or a touch screen.

[0131] It is understood that the memory in the embodiments disclosed in the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus random access memory (DRRAM). The memories described herein are intended to include, but are not limited to, these and any other suitable types of memories.

[0132] In some embodiments, the memory stores the following elements, executable modules or data structures, or a subset thereof, or an extended set thereof: an operating system and applications.

[0133] The operating system includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., which are used to implement various basic services and process hardware-based tasks. The application includes various application programs, such as a media player (Media Player), a browser (Browser), etc., which are used to implement various application services. The program for implementing the method of the embodiment of the present disclosure can be included in the application.

[0134] In the above embodiment, the processor may also call a program or instruction stored in the memory, specifically, a program or instruction stored in an application program, and is used to:

[0135] Execute the steps of the above method.

[0136] The above method can be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in the processor or an instruction in the form of software. The above processor may be a general processor, a digital signal processor (Digital Signal Processor, DSP), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The above-disclosed methods, steps and logic block diagrams can be implemented or executed. The general processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the above-disclosed method can be directly embodied as a hardware decoding processor to execute, or the hardware and software modules in the decoding processor are combined to execute. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0137] It is understood that the embodiments described in the present application can be implemented by hardware, software, firmware, middleware, microcode or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASIC), digital signal processors (DSP), digital signal processing devices (DSPD), programmable logic devices (PLD), field programmable gate arrays (FPGA), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in the present application or a combination thereof.

[0138] For software implementation, the technology of the present application can be implemented by executing the functional modules (such as procedures, functions, etc.) of the present application. The software code can be stored in a memory and executed by a processor. The memory can be implemented in the processor or outside the processor.

[0139] The present application may also provide a non-volatile storage medium for storing a computer program. When the computer program is executed by a processor, each step in the above method embodiment can be implemented.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application is described in detail with reference to the embodiments, a person skilled in the art should understand that any modification or equivalent replacement of the technical solution of the present application does not depart from the spirit and scope of the technical solution of the present application and should be included in the scope of the claims of the present application.

Claims

1. An on-orbit vertical deviation calculation system based on radar altimeter formation measurement, characterized in that: The system comprises: Sea surface height data screening module: used to perform strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flight, and screen out the effective sea surface height data for solving the strip vertical deviation from the matched satellite radar altimeter formation sea surface height data; Sea surface height slope calculation module: used to perform differential processing on the screened effective sea surface height data, and calculate the sea surface height slope data after eliminating the gross errors; Along-track accuracy calculation module: used to select the along-track slope from the sea surface high slope data, and calculate the along-track sea surface high slope accuracy according to the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points; Cross-track accuracy calculation module: used to select the cross-track slope from the sea surface high slope data, and calculate the cross-track sea surface high slope accuracy based on the sea surface high accuracy of two adjacent points used to calculate the cross-track sea surface high slope and the distance between the two adjacent points, as well as the relative orbit determination accuracy of the satellite formation; and Vertical deviation component calculation module: used to calculate the north-south component and east-west component of the vertical deviation of the strip based on the least squares principle, using the sea surface high slope data and its corresponding along / cross track sea surface high slope accuracy; The processing process of the sea level height data screening module includes: Step A1: performing strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flying according to the satellite cycle number, arc segment number and observation time information; Step A2: According to the ground track position of the satellite radar altimeter formation strip and the set search distance, the valid sea surface height data for solving the vertical deviation of the corresponding strip are screened out from the sea surface height data of the matching satellite radar altimeter formation; when screening, the data within the set radius centered on the subsatellite point of the strip is the valid data.

2. The on-orbit vertical deviation solution system based on radar altimeter formation measurement according to claim 1 is characterized in that: The processing process of the sea surface high slope calculation module includes: Step B1: Calculate the time difference Δt, longitude difference Δλ, and latitude difference between two adjacent points based on the sea surface height data of the formation satellite radar altimeter and the sea surface height difference Δh, and calculate the spherical distance d between two adjacent points ij ; Point i and point j are two adjacent points: Δt=t j -t i Dλ=λ j -l i Δh=h j -h i Where, t i , t j ,λ i ,λ j , h j ,h i Represent the time, longitude, latitude and sea level of two adjacent points respectively; Re is the average radius of the earth; Step B2: According to the time difference and distance between two adjacent points, the abnormal sea surface height difference caused by the sub-satellite point of the track passing through the land or island is eliminated, and the sea surface height difference beyond the reasonable range is eliminated; Step B3: Calculate the time t of the sea surface high slope using the height measurement data after eliminating gross errors dov , longitude λ dov ,latitude Slope ε dov and azimuth az dov ; in, is the average latitude of two adjacent points, 3. The on-orbit vertical deviation solution system based on radar altimeter formation measurement according to claim 1 is characterized in that: The processing process of the along-track accuracy calculation module includes: Step C1: Select the along-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is less than the threshold set according to the satellite altimeter sampling interval and the time difference between the formation satellites, it is along-track; Step C2: Calculate the sea surface height accuracy σ along the track according to the sea surface height accuracy of two adjacent points used to calculate the sea surface height slope along the track and the distance between the two adjacent points. dov ; in, Respectively represent the accuracy of two adjacent points; d ij Represents the spherical distance between two adjacent points i and j.

4. The on-orbit vertical deviation solution system based on radar altimeter formation measurement according to claim 1 is characterized in that: The processing process of the cross-track accuracy calculation module includes: Step D1: Select the cross-track slope in the sea surface high slope according to the time difference between two adjacent points; if the time difference between two adjacent points is greater than the threshold set according to the satellite altimeter sampling interval and the time difference between the formation satellites, it is the cross-track direction; Step D2: Calculate the cross-track sea surface height slope accuracy σ based on the sea surface height accuracy of two adjacent points used to calculate the cross-track sea surface height slope, the distance between the two adjacent points, and the relative orbit determination accuracy of the satellite formation. dov ; in, Respectively represent the accuracy of two adjacent points; σ rorb Indicates the relative orbit determination accuracy of the satellite formation; d ij Represents the spherical distance between two adjacent points i and j.

5. The on-orbit vertical deviation solution system based on radar altimeter formation measurement according to claim 1 is characterized in that: The processing process of the vertical line deviation component solving module includes: Step E1: Calculate the respective weighting factors of the sea surface high slope used to solve the vertical deviation component according to the accuracy value of the sea surface high slope along / cross track and the distance to the point to be calculated; The weight P of the sea surface height slope at the kth observation point k Set to: or Among them, d k is the distance from the sea surface high slope of the kth observation point to the point to be calculated; σ k is the standard deviation of the sea surface height slope at the kth observation point; Step E2: using the sea surface high slope data along / cross track for solving the vertical deviation component and their respective weighting factors, the north-south component and the east-west component of the vertical deviation of the strip are solved based on the least square method; The observation equation for the average value of the sea surface high slope and vertical deviation component along / cross track is: Among them, ε k 、v k and α k are the sea surface high slope along / cross track, residual and azimuth of the kth observation point respectively; n is the number of sea surface high slope observation points along / cross track; and is the average value of the north-south component and the east-west component of the observation point; According to the basic principle of least squares: Calculate the average value of the north-south component and the east-west component of the vertical deviation on the grid and 6. A method for calculating vertical deviation on-orbit based on radar altimeter formation measurement, implemented based on the system of any one of claims 1 to 5, the method comprising: Step 1) read the altimetry data of the formation measurement satellite radar altimeter, edit the data and remove abnormal values ​​in the altimetry data; Step 2) performing strip matching on the sea surface height data of adjacent tracks of the satellite radar altimeter formation flying according to the satellite cycle number, arc segment number and observation time information; Step 3) according to the ground track position of the satellite radar altimeter formation strip and the set search distance, the effective sea surface height data for solving the vertical deviation of the corresponding strip is screened out from the sea surface height data of the matching satellite radar altimeter formation; Step 4) performing differential processing on the screened effective sea surface height data, and calculating the sea surface height slope data after eliminating the gross errors; Step 5) According to the time difference between two adjacent points used to calculate the sea surface high slope, determine whether the formation measures the cross-track direction. If so, select the cross-track direction slope in the sea surface high slope data, and calculate the cross-track direction sea surface high slope accuracy according to the sea surface high accuracy of the two adjacent points used to calculate the cross-track direction sea surface high slope and the distance between the two adjacent points and the relative orbit determination accuracy of the satellite formation; If not, the along-track slope in the sea surface high slope data is selected, and the along-track sea surface high slope accuracy is calculated according to the sea surface high accuracy of two adjacent points used to calculate the along-track sea surface high slope and the distance between the two adjacent points; Step 6) The sea surface high slope data and its corresponding along / cross track sea surface high slope accuracy are used to solve the north-south component and east-west component of the vertical line deviation of the strip based on the least squares principle.

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