Ionospheric occultation inversion method and device based on non-spherical symmetry assumption

Abstract

The application provides a non-spherical assumption ionosphere occultation inversion method and device, comprising the following steps: solving occultation observation collision parameters and absolute total electron content through a data processing module; and constructing a non-spherical assumption inversion function model through a model establishing module. The application has the beneficial effect that the application solves the problem that mainstream ionosphere occultation inversion algorithms are limited by the spherical assumption, thereby making it difficult to improve inversion accuracy, and provides an ionosphere occultation inversion method based on a non-spherical assumption, thereby improving the accuracy of ionosphere occultation inversion, and the product can be applied to the fields of ionosphere weather monitoring and forecasting, navigation and positioning enhancement and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of ionospheric occultation inversion, and particularly relates to an ionospheric occultation inversion method and device based on a non-spherical symmetry assumption. BACKGROUND

[0002] The ionosphere is an important near-space environment, and its research has important scientific significance and application value. High-precision and reliable ionospheric observation data are key elements of ionospheric research. Among numerous ionospheric observation technologies, ionospheric occultation technology stands out due to its all-weather global coverage, low cost, long-term stability, high vertical resolution, and high electron density inversion accuracy. The mainstream ionospheric occultation inversion algorithms include the Abel integral inverse transform inversion algorithm and the onion peeling method inversion algorithm, which are both based on the spherical symmetry assumption. However, this assumption creates the most important model error, which becomes a constraint on improving the inversion accuracy of occultation. To further improve the accuracy of ionospheric occultation inversion, high-precision inversion algorithms based on non-spherical symmetry assumption should be developed using external data or prior information. SUMMARY

[0003] Therefore, the application aims to provide an ionospheric occultation inversion method and device based on a non-spherical symmetry assumption to solve the problem that mainstream ionospheric occultation inversion algorithms are limited by the spherical symmetry assumption, making it difficult to improve inversion accuracy.

[0004] To achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0005] In a first aspect, an ionospheric occultation inversion method based on a non-spherical symmetry assumption includes the following steps:

[0006] S1, calculating occultation observation collision parameters and absolute total electron content through a data processing module;

[0007] S2, constructing a non-spherical symmetry assumption inversion function model through a model establishment module;

[0008] In step S1, the data processing module is used to calculate occultation observation collision parameters and absolute total electron content, including:

[0009] S11, generating an ionospheric occultation additional phase file after processing the original data of ionospheric occultation observation, and using the ionospheric occultation additional phase file as an input file for ionospheric occultation inversion;

[0010] S12, calculating the coordinates and collision parameters p of the occultation point P according to the vertical relationship and collinear relationship under the assumption of straight-line propagation of radio waves;

[0011] S13, after the cycle slip detection and repair of the dual-frequency additional phase observation value of the ionospheric occultation additional phase file, the high-frequency noise is suppressed by using the sliding window smoothing filter, and then the dual-frequency phase is combined to obtain the relative total electron content;

[0012] S14, the observation data of the non-occultation period is used to correct the observation data of the occultation period, and the relative TEC on both sides of the maximum collision parameter is highly reordered, the relative TEC of the non-occultation period is three times spline interpolation to the collision height corresponding to the occultation period, and the absolute total electron content is obtained by difference;

[0013] In step S2, a non-spherical assumption inversion function model is constructed by a model establishment module, including:

[0014] S21, deduce the electron density inversion formula, the top electron density estimation, and construct the recursive relationship by using the three-dimensional ionospheric empirical model;

[0015] S22, generate ionospheric electron density profile.

[0016] Further, in step S21, the electron density inversion formula, the top electron density estimation, and the recursive relationship are constructed by using the three-dimensional ionospheric empirical model, including:

[0017] The absolute total electron content is the integral of the electron density on the signal path, and the expression is formula (5);

[0018] Under the assumption of straight-line propagation of radio waves, the expression of the absolute total electron content of the BC segment is formula (6);

[0019] There are several observations in the occultation period. If the collision parameters of the continuous observations are used to make concentric circles, the BC segment path is divided into the sum of the line segments between the spherical layers, and the electron density between the spherical layers is assumed to be linearly changed, then the integral can be solved, and the absolute total electron content is linearized as a linear combination of the electron density at the intersection points of the path and each spherical layer, and the expression is formula (7);

[0020] Thus, the electron density inversion formula (9) is obtained;

[0021] The expression of the top occultation cut point electron density estimation is formula (10);

[0022] Under the assumption of non-spherical symmetry, given additional information, the electron density at the higher spherical layer occultation cut point is recursively calculated to the electron density at the intersection point corresponding to the observation path, and by assuming that the ratio of the electron density values of the corresponding points of the actual ionosphere is consistent with the empirical model, the recursive relationship is constructed, and the expression is formula (11).

[0023] Further, in step S22, the ionospheric electron density profile is generated, including:

[0024] The recursive relationship is substituted into the electron density inversion formula, and after estimating the electron density at the top occultation point, the electron density inversion formula is used to derive the electron density at all occultation points from high to low step by step, so as to realize ionospheric occultation inversion under the assumption of non-spherical symmetry, and finally generate the ionospheric electron density profile.

[0025] Further, in step S12, under the assumption of straight-line propagation of radio waves, the coordinates of the occultation point P and the collision parameter p are calculated according to the vertical relationship and the collinear relationship, and the expressions are formula (1) and formula (2):

[0026] (1)

[0027] (2)

[0028] In the formula, represents the space vector of the occultation point P; represents the space vector of the center of the earth O; represents the space vector of the navigation satellite coordinate A; represents the space vector of the low-orbit satellite coordinate C; the denominator of the fraction represents the second order norm; the numerator of the fraction represents the scalar product; represents the collision parameter.

[0029] Further, in step S13, the relative total electron content is expressed as formula (3):

[0030] (3)

[0031] In the formula, represents the relative total electron content on the signal path; represents the additional phase value on the carrier signal 1; represents the additional phase value on the carrier signal 2; represents the square of the frequency of the carrier signal 1; represents the square of the frequency of the carrier signal 2.

[0032] Further, in step S14, the absolute total electron content is expressed as formula (4):

[0033] (4)

[0034] In the formula, represents the absolute total electron content of the BC segment on the occultation observation signal path; represents the relative total electron content of the AC segment on the occultation observation signal path; represents the relative total electron content of the AB segment on the non-occultation observation signal path.

[0035] Further, formula (5), formula (6) and formula (7) are respectively:

[0036] (5)

[0037] In the formula, denotes the absolute total electron content on the path; denotes the path; denotes the electron density; denotes the microelement of the path;

[0038] (6)

[0039] In the formula, denotes the absolute total electron content of the BC segment; denotes the collision parameter; denotes the geocentric distance at the low-orbit satellite; denotes the geocentric distance at the microelement; denotes the electron density at the microelement; denotes the electron density at the microelement symmetric to the occultation cut point; denotes the microelement of the path;

[0040] (7)

[0041] In the formula, denotes the index of the observation after the observation sequence is sorted in ascending order of the collision parameter; denotes the collision parameter; denotes the absolute total electron content; and denotes the electron density at the two intersection points of the path and each spherical layer; denotes the dimensionless coefficient; The expression of is formula (8);

[0042] (8).

[0043] Further, formula (9), formula (10) and formula (11) are respectively:

[0044] (9)

[0045] (10)

[0046] In the formula, denotes the collision parameter of the top spherical layer; denotes the collision parameter of a certain spherical layer adjacent to the top; denotes the estimated value of the electron density of the top spherical layer; Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top.

[0047] (11)

[0048] In the formula, Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top. Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top. Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top. Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top. Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top. Nt (t) represents the absolute total electron content of a certain layer of the sphere close to the top.

[0049] Further, the ionospheric occultation additional phase file contains the position, speed information of the navigation satellite and the low-orbit satellite and the double-frequency additional phase observation value information.

[0050] In a second aspect, based on the same aspect, the application further provides a non-spherical assumption ionospheric occultation inversion device, comprising a data processing module and a model establishing module; the data processing module is used for solving the occultation observation collision parameter and the absolute total electron content; the model establishing module is used for constructing the non-spherical assumption inversion function model.

[0051] Compared with the prior art, the non-spherical assumption ionospheric occultation inversion method and device have the following beneficial effects:

[0052] The application solves the problem that the mainstream ionospheric occultation inversion algorithm is limited by the spherical symmetry assumption, so that the inversion precision is difficult to improve; the application provides a non-spherical assumption ionospheric occultation inversion method, so that the precision of ionospheric occultation inversion can be improved, and the product can be applied to the fields of ionospheric weather monitoring and forecasting, navigation and positioning enhancement and the like. BRIEF DESCRIPTION OF DRAWINGS

[0053] The accompanying drawings, which form a part of the present application, are used to provide a further understanding of the present application, and the illustrative embodiments thereof and their descriptions serve to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0054] Fig. 1 The technical roadmap described in the embodiments of the application;

[0055] Fig. 2 The occultation observation geometry diagram described in the embodiments of the application. DETAILED DESCRIPTION

[0056] It should be noted that, in the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0057] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0058] In the description of the present application, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0059] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0060] As Figs. 1-2 shown, a non-spherical ionosphere occultation inversion method of assumption includes the following steps:

[0061] S1, calculating the occultation observation collision parameter and the absolute total electron content through the data processing module;

[0062] S2, constructing a non-spherical inversion function model through a model establishing module;

[0063] The mainstream ionosphere occultation inversion algorithm is limited by the spherical symmetry assumption, and the inversion accuracy is difficult to improve. The present application improves the inversion accuracy by proposing a non-spherical ionosphere occultation inversion algorithm. The specific steps are as follows:

[0064] 1, calculating the occultation observation collision parameter and the absolute total electron content

[0065] The raw data of ionospheric occultation observation is decoded and checked, low-orbit satellite is tracked, and data is preprocessed to generate an ionospheric occultation additional phase file, which contains the position and speed of navigation satellite and low-orbit satellite, double-frequency additional phase observation value and the like information. The ionospheric occultation additional phase file is used as an input file for ionospheric occultation inversion.

[0066] Since the bending angle caused by the refraction of L-band navigation satellite signal of ionosphere during the period of intense change of ionosphere does not exceed 0.03 degrees, it can be assumed that the radio wave propagates along a straight line. Under the assumption that the radio wave propagates along a straight line, the occultation tangent point P is the foot of the perpendicular from the center of the earth O to the radio wave path AC, and the coordinates of the occultation tangent point P and the collision parameter p can be calculated according to the perpendicular relationship and the collinear relationship:

[0067] (1)

[0068] (2)

[0069] In the formula, represents the space vector of the occultation tangent point P; represents the space vector of the center of the earth O; represents the space vector of the navigation satellite coordinate A; represents the space vector of the low-orbit satellite coordinate C; the denominator of the fraction represents the second order norm; the numerator of the fraction represents the scalar product; represents the collision parameter.

[0070] After the double-frequency additional phase observation value of the ionospheric occultation additional phase file is detected and repaired for cycle slip, high-frequency noise is suppressed by using a sliding window smoothing filter, and then the double-frequency phase is combined to obtain relative total electron content (TEC):

[0071] (3)

[0072] In the formula, represents the relative total electron content on the signal path; represents the additional phase value on the carrier signal 1; represents the additional phase value on the carrier signal 2; represents the square of the frequency of the carrier signal 1; represents the square of the frequency of the carrier signal 2.

[0073] Because the ionospheric TEC is usually small and the ionospheric variation and the change of the ionospheric plane azimuth are also small, the low earth orbit satellite is considered to be in the same ionospheric background and the same ionospheric plane during the non-occultation period (e.g. at point B) and the occultation period (e.g. at point C). Therefore, the observation data during the non-occultation period can be used to correct the observation data during the occultation period, and the absolute TEC can be obtained:

[0074] (4)

[0075] wherein, represents the absolute TEC of the BC segment of the occultation observation signal path; represents the relative TEC of the AC segment of the occultation observation signal path; represents the relative TEC of the AB segment of the non-occultation observation signal path.

[0076] Considering the observation interval of the receiver, in order to correct more strictly, the relative TEC observed during the non-occultation period needs to be interpolated to the same collision height of the relative TEC observed during the occultation period, so as to obtain the absolute TEC by difference.

[0077] 2. Constructing the non-spherical symmetry inversion function model

[0078] According to the definition, the absolute TEC is the integral of the electron density on the signal path:

[0079] (5)

[0080] wherein, represents the absolute TEC on the path; represents the path; represents the electron density; represents the infinitesimal of the path.

[0081] Under the assumption of straight-line propagation of radio waves, the absolute TEC of the BC segment can be expressed as:

[0082] (6)

[0083] wherein, represents the absolute TEC of the BC segment; represents the collision parameter; represents the geocentric distance at the low earth orbit satellite; represents the geocentric distance at the infinitesimal; represents the electron density at the infinitesimal; represents the electron density at the infinitesimal symmetric to the occultation tangent point; represents the infinitesimal of the path.

[0084] If the impact parameters of these consecutive observations are used to draw concentric circles, the BC segment path is divided into a sum of line segments between the layers. Assuming the electron density varies linearly between layers, the integral can be solved and the absolute total electron content linearized as a linear combination of the electron densities at the intersection points of the path with each layer:

[0085] (7)

[0086] where, denotes the index of the observation in the sorted sequence of observations by impact parameter from small to large; denotes the impact parameter; denotes the absolute total electron content; and denotes the electron density at the two intersection points of the path with each layer; denotes the dimensionless coefficient, which is calculated by the following formula:

[0087] (8)

[0088] Thus, the electron density inversion formula can be obtained:

[0089] (9)

[0090] Obviously, given the absolute total electron content and impact parameter of the observation, the electron density at the occultation cut point of a layer is determined by the electron densities at the intersection points of the path with all higher layers. Under the assumption of spherical symmetry, the electron density at the occultation cut point of a higher layer can naturally replace the electron density at the intersection point corresponding to the observation path, thereby deducing the electron density at all occultation cut points from high to low. The electron density at the top occultation cut point is estimated as follows:

[0091] (9)

[0092] where, denotes the impact parameter of the top layer; denotes the impact parameter of a layer adjacent to the top; denotes the estimated value of the electron density of the top layer; denotes the absolute total electron content of a layer adjacent to the top.

[0093] However, under the assumption of non-spherical symmetry, additional information should be given to realize the recursion of the electron density at the higher spherical layer occultation cut point to the electron density at the intersection corresponding to this observation path. The present application utilizes a three-dimensional ionospheric empirical model, such as the International Reference Ionosphere (IRI) model, the NeQuick model, etc., to construct a recursive relationship by assuming that the ratio of the electron density values of the corresponding points of the actual ionosphere is consistent with the empirical model:

[0094] (11)

[0095] In the formula, denotes the electron density at time M point; denotes the electron density at time P point; denotes the actual inversion; denotes the model. Substitute the recursive relationship into the electron density inversion formula. After estimating the electron density at the top occultation cut point, the electron density inversion formula can be used to gradually deduce the electron density at all occultation cut points from high to low, realizing the ionospheric occultation inversion under the assumption of non-spherical symmetry.

[0096] The present application also provides an ionospheric occultation inversion device under the assumption of non-spherical symmetry, comprising a data processing module and a model establishing module; the data processing module is used for solving the collision parameters and the absolute total electron content of the occultation observation; the model establishing module is used for constructing the inversion function model under the assumption of non-spherical symmetry.

[0097] The advantages of the present application are:

[0098] The present application solves the problem that the mainstream ionospheric occultation inversion algorithm is limited by the spherical symmetry assumption, thereby making it difficult to improve the inversion accuracy; the present application provides an ionospheric occultation inversion method under the assumption of non-spherical symmetry, thereby improving the accuracy of ionospheric occultation inversion, and the product can be applied in the fields of ionospheric weather monitoring and forecasting, navigation and positioning enhancement, etc.

[0099] Example 1

[0100] (1) Collect the ionospheric occultation additional phase files of COSMIC-2 satellites in January 2025; collect NeQuick-2 model data (CCIR empirical coefficient file and MODIP geomagnetic latitude file);

[0101] (2) Process the navigation satellite and low-orbit satellite orbit data of the ionospheric occultation additional phase file, and calculate the collision parameters through geometric relationship;

[0102] (2) Process the navigation satellite and low-orbit satellite orbit data of the ionospheric occultation additional phase file, and calculate the collision parameters through geometric relationship;

[0103] ​(3) The dual-frequency additional phase data of the ionospheric occultation additional phase file is processed, the smooth additional phase data is obtained through the cycle slip detection and repair and the sliding window smoothing, the dual-frequency combination calculation is performed on the smooth additional phase data, the ionospheric relative TEC on different paths is obtained, the relative TEC on both sides of the maximum collision parameter is reordered in height, and finally the relative TEC in the non-occultation period is interpolated to the collision height equivalent to the occultation period by the cubic spline interpolation, and the absolute TEC is obtained by difference;

[0104] (4) The electron density model values at the intersection points of the wave path and each sphere layer are calculated based on the NeQuick-2 model, after the electron density at the top occultation intersection point is estimated, the electron density at all occultation intersection points is gradually derived from high to low by using the ionospheric occultation inversion method based on the assumption of asphericity, and finally the ionospheric electron density profile product is generated.

[0105] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for ionospheric occultation inversion based on a non-spherical symmetry assumption, characterized in that: Includes the following steps: S1. The occultation observation collision parameters and absolute total electron content are calculated through the data processing module; S2. Construct a non-spherically symmetric assumption inversion function model through the model building module; In step S1, the occultation observation collision parameters and absolute total electron content are calculated by the data processing module, including: S11. After processing the raw data of ionospheric occultation observations, generate an additional phase file for ionospheric occultation, and use the additional phase file for ionospheric occultation as the input file for ionospheric occultation inversion. S12. Under the assumption of rectilinear propagation of radio waves, calculate the coordinates of the occultation point P and the collision parameter p based on the perpendicular and collinear relationships. S13. After cycle slip detection and repair of the dual-frequency additional phase observations in the ionospheric occultation additional phase file, high-frequency noise is suppressed by using a sliding window smoothing filter, and then the dual-frequency phases are combined to obtain the relative total electron content. S14. Use the observation data of the non-occultation period to correct the observation data of the occultation period, reorder the relative TEC on both sides of the maximum collision parameter, interpolate the cubic spline of the relative TEC of the non-occultation period to the same collision height as the occultation period, and obtain the absolute total electron content by difference. In step S2, a non-spherical symmetric assumption inversion function model is constructed through the model building module, including: S21. Derive the electron density inversion formula, estimate the top electron density, and construct recursive relationships using a three-dimensional ionospheric empirical model; S22, generates electron density profile of the ionosphere; In step S21, the electron density inversion formula, the top electron density estimation, and the construction of recursive relationships using a three-dimensional ionospheric empirical model are derived, including: The absolute total electron content is the integral of the electron density along the signal path, expressed as formula (5); Under the assumption of rectilinear propagation of radio waves, the expression for the absolute total electron content of segment BC is formula (6); There are several observations during the occultation period. If the collision parameters of the continuous observations are used to form concentric circles, the BC segment path is decomposed into the sum of line segments between several spheres. Assuming that the electron density between the spheres changes linearly, the integral can be solved to linearize the absolute total electron content into a linear combination of the electron density at the intersection of the path and each sphere. The expression is formula (7). Thus, the electron density inversion formula (9) is obtained; The expression for estimating the electron density at the top occultation tangent point is Equation (10); Under the assumption of non-spherical symmetry, given additional information, the electron density at the tangent point of the higher spherical occultation is recursively derived to the electron density at the intersection point of the observation path. Using the three-dimensional ionospheric empirical model, the recursive relationship is constructed by assuming that the ratio of the electron density values ​​at the corresponding points in the actual ionospheric is consistent with the empirical model. The expression is formula (11). In step S22, the ionospheric electron density profile is generated, including: Substituting the recursive relationship into the electron density inversion formula, after estimating the electron density at the top occultation tangent point, the electron density at all occultation tangent points is gradually derived from high to low using the electron density inversion formula, thus realizing ionospheric occultation inversion under the assumption of non-spherical symmetry, and finally generating the ionospheric electron density profile. Formulas (9), (10), and (11) are respectively: (9) (10) In the formula, Indicates the collision parameters of the top spherical layer; This represents the collision parameters of a spherical layer near the top. This represents the estimated electron density of the top spherical shell; This represents the absolute total electron content of a certain spherical layer near the top. and This represents the electron density at two points where the path intersects with each of the spheres; Indicates a dimensionless coefficient; (11) In the formula, express Electron density at point M at time M; express Electron density at point P at time P; Indicates actual inversion; Representation model.

2. The ionospheric occultation inversion method based on the non-spherical symmetry assumption according to claim 1, characterized in that: In step S12, under the assumption of rectilinear propagation of radio waves, the coordinates of the occultation tangent point P and the collision parameter p are calculated based on the perpendicular and collinear relationships, expressed as formulas (1) and (2): (1) (2) In the formula, The spatial vector representing the tangent point P of the occultation; Represents the spatial vector at the geocentric point O; The spatial vector representing the coordinates of navigation satellite A; The spatial vector representing the coordinates C of a low-Earth orbit satellite; the denominator of the fraction. Denotes the second norm; the numerator of a fraction. Represents the dot product; This represents the collision parameters.

3. The ionospheric occultation inversion method based on the non-spherical symmetry assumption according to claim 1, characterized in that: In step S13, the expression for the relative total electron content is formula (3): (3) In the formula, Indicates the relative total electron content along the signal path; This represents the additional phase value on carrier signal 1; This represents the additional phase value on carrier signal 2; Represents the square of the frequency of carrier signal 1; It represents the square of the frequency of carrier signal 2.

4. The ionospheric occultation inversion method based on the non-spherical symmetry assumption according to claim 1, characterized in that: In step S14, the expression for the absolute total electron content is formula (4): (4) In the formula, This represents the absolute total electron content in segment BC along the occultation observation signal path; This indicates the relative total electron content in segment AC along the occultation observation signal path; This represents the relative total electron content of segment AB along the non-occultation observation signal path.

5. The ionospheric occultation inversion method based on the non-spherical symmetry assumption according to claim 1, characterized in that: Formulas (5), (6), and (7) are respectively: (5) In the formula, Indicates the absolute total electron content along the path; Indicates a path; Indicates electron density; The infinitesimal element representing the path; (6) In the formula, Indicates the absolute total electron content of segment BC; Indicates collision parameters; This indicates the Earth's center distance at the location of a low-Earth orbit satellite; This represents the geocentric distance at the infinitesimal element. This represents the electron density at the infinitesimal element; This represents the electron density at a point symmetrical about the tangent point of the occultation. The infinitesimal element representing the path; (7) In the formula, This indicates the index of the observation after the observation sequence is sorted by collision parameter from smallest to largest; Indicates collision parameters; Indicates the absolute total electron content; The expression for is formula (8); (8)。 6. The ionospheric occultation inversion method based on the non-spherical symmetry assumption according to claim 1, characterized in that: The ionospheric occultation supplemental phase file contains position and velocity information of navigation satellites and low-Earth orbit satellites, as well as dual-frequency supplemental phase observations.

7. An ionospheric occultation inversion device based on a non-spherical symmetry assumption, employing the ionospheric occultation inversion method based on a non-spherical symmetry assumption as described in any one of claims 1 to 6, characterized in that: It includes a data processing module and a model building module; the data processing module is used to calculate the collision parameters and absolute total electron content of occultation observations; the model building module is used to construct a non-spherical symmetric assumption inversion function model.

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