Starlight refraction simulation method and device considering three-dimensional refractive index distribution characteristics

Abstract

The present application relates to a starlight refraction simulation method and device considering the characteristics of three-dimensional refractive index distribution. The method constructs a global atmospheric refractive index field through the global reanalysis data set at the current time according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system; calculates the refractive index at the interpolation points of interest in the starlight path update and the refractive index gradient at the interpolation points of interest in the starlight path update; uses a numerical calculation method to calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation; and calculates the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process. This method avoids the simplification of the starlight refraction process by a two-dimensional system and accurately simulates the starlight refraction process in three-dimensional space; considering the characteristics of three-dimensional refractive index distribution, it accurately simulates the influence of the refractive index gradient in latitude, longitude, and radial direction on the starlight refraction process, and accurately reflects the three-dimensional path geometric characteristics in the starlight refraction process.

Description

Technical Field

[0001] The present application relates to the technical field of celestial navigation, and particularly to a starlight refraction simulation method and device considering the characteristics of three-dimensional refractive index distribution. Background Technique

[0002] Starlight refraction refers to the process in which when the light from a star passes through the Earth's atmosphere, due to the change in the atmospheric refractive index in the atmosphere, the propagation direction of the light is deflected. This phenomenon makes the apparent position of the star observed by the spacecraft near the limb slightly higher than its actual position in space. In the ground simulation of the starlight atmospheric refraction navigation system, it is necessary to simulate this refraction process with high precision. The spacecraft uses the simulated high-precision starlight refraction angle information as the observation value to achieve subsequent navigation solution.

[0003] Generally, in the ground simulation of the starlight atmospheric refraction navigation system, the refraction process of starlight passing through the atmosphere is simplified, and the three-dimensional refraction process is simplified to a two-dimensional system. At the same time, only the change of meteorological data in height is considered, assuming that it is independent of time, longitude and latitude. Therefore, it is difficult to ensure high-precision starlight refraction simulation results. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a starlight refraction simulation method and device considering the characteristics of three-dimensional refractive index distribution, which can ensure that the simulation accuracy of refraction information such as starlight refraction angle meets the requirements of the starlight atmospheric refraction navigation scenario.

[0005] A starlight refraction simulation method considering the characteristics of three-dimensional refractive index distribution, the method includes:

[0006] Step S1: According to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system, construct a global atmospheric refractive index field through the global reanalysis dataset of the current time.

[0007] Step S2: Calculate the refractive index at the interpolation point of interest in the starlight path update according to the global atmospheric refractive index field.

[0008] Step S3: Calculate the refractive index gradients in the latitude, longitude and radial directions at the interpolation point of interest in the starlight path update according to the refractive index at the interpolation point of interest.

[0009] Step S4: Construct a starlight refraction path model based on the three-dimensional eikonal equation, and use a numerical calculation method to calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation.

[0010] Step S5: Calculate the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process.

[0011] A starlight refraction simulation device considering the characteristics of three-dimensional refractive index distribution, the device includes:

[0012] A global atmospheric refractive index field construction module, which is used to construct a global atmospheric refractive index field according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system through the global reanalysis dataset of the current time.

[0013] A refractive index calculation module at the interpolation point of interest, which is used to calculate the refractive index at the interpolation point of interest in the starlight path update according to the global atmospheric refractive index field.

[0014] A refractive index gradient calculation module, which is used to calculate the refractive index gradients in the latitude, longitude, and radial directions at the interpolation point of interest in the starlight path update according to the refractive index at the interpolation point of interest.

[0015] A starlight refraction model path update module based on the three-dimensional eikonal equation, which is used to construct a starlight refraction path model based on the three-dimensional eikonal equation and calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation by using numerical calculation methods.

[0016] A starlight refraction angle calculation module in the starlight path update, which is used to calculate the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process.

[0017] The above starlight refraction simulation method and device considering the characteristics of three-dimensional refractive index distribution, the method includes: constructing a global atmospheric refractive index field according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system through the global reanalysis dataset of the current time; calculating the refractive index at the interpolation point of interest in the starlight path update; then, calculating the refractive index gradient at the interpolation point of interest in the starlight path update; calculating the updated path of the starlight refraction model based on the three-dimensional eikonal equation by using numerical calculation methods; calculating the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process. This method avoids the simplification of the starlight refraction process by the two-dimensional system and can simulate the starlight refraction process in three-dimensional space with high precision; considering the characteristics of three-dimensional refractive index distribution, it can simulate the influence of the refractive index gradients in latitude, longitude, and radial directions on the starlight refraction process with high precision, and can reflect the three-dimensional path geometric characteristics in the starlight refraction process with high precision. Description of the Drawings

[0018] Figure 1 It is a schematic flowchart of a starlight refraction simulation method considering the characteristics of three-dimensional refractive index distribution in an embodiment;

[0019] Figure 2 It is a flowchart of a starlight refraction simulation method considering the characteristics of three-dimensional refractive index distribution in an embodiment;

[0020] Figure 3Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the radial distance of the starlight path from the center of the earth;

[0021] Figure 4 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the latitude of the starlight path;

[0022] Figure 5 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the longitude of the starlight path;

[0023] Figure 6 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the first partial differential component;

[0024] Figure 7 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the second partial differential component;

[0025] Figure 8 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the third partial differential component;

[0026] Figure 9 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the radial gradient of the refractive index;

[0027] Figure 10 Results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in an embodiment: Schematic diagram of the change in the refraction angle during the update of the starlight path. Detailed implementation manners

[0028] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0029] In one embodiment, as Figure 1 、 Figure 2 shown, a starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics is provided, and the method includes the following steps:

[0030] Step S1: According to the simulation scene time of the starlight atmospheric refraction navigation ground simulation system, construct a global atmospheric refractive index field through the global reanalysis dataset at the current time.

[0031] Specifically, according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system, a global atmospheric refraction index field is constructed through a global three-dimensional atmospheric data set or other measured global three-dimensional atmospheric parameters.

[0032] According to the fifth-generation global atmospheric reanalysis data set released by the European Centre for Medium-Range Weather Forecasts, meteorological data at an altitude of 18 km - 84 km is selected for processing. Its horizontal resolution is 0.75° × 0.75°, and the vertical resolution is set to 20 m, with a total of 3301 layers, so as to obtain the global atmospheric refraction index field at the current simulation moment.

[0033] Step S2: Calculate the refraction index at the interpolation points of interest in the starlight path update according to the global atmospheric refraction index field.

[0034] Step S3: Calculate the refraction index gradients in the latitude, longitude, and radial directions at the interpolation points of interest in the starlight path update according to the refraction index at the interpolation points of interest.

[0035] Step S4: Construct a starlight refraction path model based on the three-dimensional eikonal equation, and use a numerical calculation method to calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation.

[0036] Step S5: Calculate the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process.

[0037] In the above starlight refraction simulation method considering the three-dimensional refraction index distribution characteristics, the method includes: according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system, constructing a global atmospheric refraction index field through the global reanalysis data set at the current time; calculating the refraction index at the interpolation points of interest in the starlight path update; then, calculating the refraction index gradients at the interpolation points of interest in the starlight path update; using a numerical calculation method to calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation; calculating the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process. This method avoids the simplification of the starlight refraction process in the two-dimensional system, and can simulate the starlight refraction process in three-dimensional space with high precision; considering the three-dimensional refraction index distribution characteristics, it can simulate the influence of the refraction index gradients in latitude, longitude, and radial directions on the starlight refraction process with high precision, and can reflect the three-dimensional path geometric characteristics in the starlight refraction process with high precision.

[0038] In one embodiment, step S2 includes: calculating the refraction index at the interpolation points of interest in the starlight path update according to the global atmospheric refraction index field; where the expression of the refraction index at the interpolation points of interest is:

[0039] ;

[0040] The expression for the refractive index at the lower layer adjacent to the interpolation point of interest is as follows:

[0041] ;

[0042] Among them, is the refractive index at the interpolation point of interest, is the refractive index at the lower layer adjacent to the interpolation point of interest. The th layer is the lower layer adjacent to the interpolation point of interest, and are respectively the radial distances from the center of the Earth of the th layer and the th layer, is the serial number of the global atmospheric refractive index grid point near the interpolation point of interest; ; , , , are respectively the radial distance, latitude, and longitude from the center of the Earth at the interpolation point of interest, , are respectively the latitude and longitude of the global atmospheric refractive index grid point near the interpolation point of interest, , are respectively the latitude and longitude of the global atmospheric refractive index grid point near the interpolation point of interest.

[0043] Specifically, if the th layer is the lower layer adjacent to the interpolation point of interest, and the radial distance from the center of the Earth of this layer is , then the refractive index at the lower layer adjacent to the interpolation point of interest is as shown in the above expression for the refractive index at the lower layer adjacent to the interpolation point of interest.

[0044] Assume that the refractive index is in an exponential form between the th layer and the th layer. Then the refractive index at the interpolation point of interest is as shown in the above expression for the refractive index at the interpolation point of interest.

[0045] In one embodiment, step S3 includes: calculating the refractive index gradient in the latitude direction of the interpolation point of interest in the starlight path update according to the refractive index at the interpolation point of interest. The expression for the refractive index gradient in the latitude direction of the interpolation point of interest in the starlight path update is:

[0046] ;

[0047] Among them, The refractive index gradient of the interpolation point of interest in the latitude direction during the starlight path update, 、 、 are respectively the radial distance, latitude, and longitude from the center of the Earth at the interpolation point of interest, 、 are respectively the radial distances from the center of the Earth of the th layer and the th layer, and are respectively the radial distance and latitude of the starlight refraction point from the center of the Earth during the numerical update process, is the refractive index function.

[0048] Calculate the refractive index gradient of the interpolation point of interest in the longitude direction during the starlight path update according to the refractive index at the interpolation point of interest; wherein, the expression for the refractive index gradient of the interpolation point of interest in the longitude direction during the starlight path update is:

[0049] ;

[0050] wherein, is the refractive index gradient of the interpolation point of interest in the longitude direction during the starlight path update, is the longitude of the starlight refraction point from the center of the Earth during the numerical update process.

[0051] Calculate the refractive index gradient of the interpolation point of interest in the radial direction during the starlight path update according to the refractive index at the interpolation point of interest; wherein, the expression for the refractive index gradient of the interpolation point of interest in the radial direction during the starlight path update is:

[0052] ;

[0053] wherein, is the refractive index gradient of the interpolation point of interest in the radial direction during the starlight path update.

[0054] In one embodiment, step S4 includes: constructing a starlight refraction path model based on the three-dimensional eikonal equation as:

[0055] ;

[0056] wherein, is the arc length along the light ray path, 、 and are respectively the partial differential components of in the radial direction, latitude direction, and longitude direction, is the length of the light ray path, 、 and are respectively the radial distance, latitude, and longitude of the starlight refraction point from the center of the Earth during the numerical update process, is the refractive index at the starlight refraction point during the numerical update process.

[0057] Define the state vector , convert the starlight refraction path model based on the eikonal equation into the form of the first derivative of the state vector (i.e., ), and use the fourth-order Runge-Kutta method to numerically update the starlight refraction path; among them, the update of the variables related to the refractive index during the update process is calculated according to steps S2 and S3. Preferably: Given the update step size as .

[0058] In one embodiment, step S5 includes: establishing a spherical coordinate system; the tangent vector of the starlight direction in the spherical coordinate system is expressed as:

[0059] ;

[0060] where, is the tangent vector of the starlight direction in the spherical coordinate system, is the arc length along the light path, , and are respectively the radial distance, latitude, and longitude of the starlight refraction point from the center of the Earth during the numerical update process;

[0061] Convert the tangent vector of the starlight direction in the spherical coordinate system to the Cartesian rectangular coordinate system; among them, the expression of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system is:

[0062] ;

[0063] The three-dimensional component expression of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system is:

[0064] ;

[0065] where, is the tangent vector of the starlight direction in the Cartesian rectangular coordinate system, are respectively the three-dimensional components of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system, , and are respectively the radial distance, latitude, and longitude of the starlight refraction point from the center of the Earth during the numerical update process.

[0066] At the During the update process, the angle change of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system is used as the change of the starlight refraction angle; the changes of the starlight refraction angle in each starlight path update process are summed to obtain the starlight refraction angle in the starlight path update.

[0067] Specifically, the starlight refraction angle in the starlight path update , where is the number of times during the starlight path update.

[0068] In one embodiment, the expression for the change of the starlight refraction angle in the Cartesian rectangular coordinate system is:

[0069] ;

[0070] Among them, is the change of the starlight refraction angle in the Cartesian rectangular coordinate system, is the arctangent function, and are respectively the tangent vectors of the starlight direction in the Cartesian rectangular coordinate system in the th and th numerical value updates.

[0071] The starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics is as shown in Figure 2 .

[0072] It should be understood that although the steps in the flowchart of Figure 1 are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 at least a part of the steps in

[0073] In a simulation embodiment, taking the latitude of the starlight incident puncture point as 60.1° N, the longitude as 169.4° W, the azimuth angle relative to the north direction as 172.088°, and the incident zenith angle as 97.8264° as an example of the implementation scenario of the ground navigation simulation system, 31 Dec 2023 00:00:00.000 UTCG is used as the navigation simulation time. The simulation results of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics are as shown in Figures 3 to 10 , where Figure 3Schematic diagram of the change in the radial distance of the starlight path from the center of the earth Figure 4 Schematic diagram of the change in the latitude of the starlight path Figure 5 Schematic diagram of the change in the longitude of the starlight path Figure 6 Schematic diagram of the change in the first partial differential component Figure 7 Schematic diagram of the change in the second partial differential component Figure 8 Schematic diagram of the change in the third partial differential component Figure 9 Schematic diagram of the change in the radial gradient of the refractive index Figure 10 Schematic diagram of the change in the refraction angle during the update of the starlight path

[0074] In one embodiment, a starlight refraction simulation device considering the characteristics of the three-dimensional refractive index distribution is provided, including: a global atmospheric refractive index field construction module, a refractive index calculation module at an interpolation point of interest, a refractive index gradient calculation module, a starlight refraction model path update module based on the three-dimensional eikonal equation, and a starlight refraction angle calculation module during the starlight path update, where:

[0075] The global atmospheric refractive index field construction module is used to construct a global atmospheric refractive index field according to the simulation scenario time of the starlight atmospheric refraction navigation ground simulation system through the global reanalysis dataset at the current time.

[0076] The refractive index calculation module at an interpolation point of interest is used to calculate the refractive index at the interpolation point of interest during the update of the starlight path according to the global atmospheric refractive index field.

[0077] The refractive index gradient calculation module is used to calculate the refractive index gradients in the latitude, longitude, and radial directions at the interpolation point of interest during the update of the starlight path according to the refractive index at the interpolation point of interest.

[0078] The starlight refraction model path update module based on the three-dimensional eikonal equation is used to construct a starlight refraction path model based on the three-dimensional eikonal equation and calculate the updated path of the starlight refraction model based on the three-dimensional eikonal equation by using a numerical calculation method.

[0079] The starlight refraction angle calculation module during the starlight path update is used to calculate the starlight refraction angle during the starlight path update according to the tangent method in the starlight refraction process.

[0080] In one of the embodiments, the refractive index calculation module at an interpolation point of interest is further used to calculate the refractive index at the interpolation point of interest during the update of the starlight path according to the global atmospheric refractive index field by using the expression of the refractive index at the interpolation point of interest during the update of the starlight path as described above.

[0081] In one embodiment, the refractive index gradient calculation module is further configured to calculate the refractive index gradient in the latitude direction of the starlight path update at the interpolation point of interest according to the refractive index at the interpolation point of interest, using the expression of the refractive index gradient in the latitude direction of the starlight path update at the interpolation point of interest as described above; calculate the refractive index gradient in the longitude direction of the starlight path update at the interpolation point of interest according to the refractive index at the interpolation point of interest, using the expression of the refractive index gradient in the longitude direction of the starlight path update at the interpolation point of interest; calculate the refractive index gradient in the radial direction of the starlight path update at the interpolation point of interest according to the refractive index at the interpolation point of interest, using the expression of the refractive index gradient in the radial direction of the starlight path update at the interpolation point of interest as described above.

[0082] In one embodiment, the starlight refraction model path update module based on the eikonal equation in three dimensions is further configured to construct a starlight refraction path model based on the eikonal equation in three dimensions as shown in the expression of the starlight refraction path model based on the eikonal equation in three dimensions as described above; define a state vector , and convert the starlight refraction path model based on the eikonal equation in three dimensions into form, and perform numerical update of the starlight refraction path using the fourth-order Runge-Kutta method; wherein, the update of the variables related to the refractive index during the update process is calculated according to step S2 and step S3.

[0083] In one embodiment, the starlight refraction angle calculation module in the starlight path update is further configured to establish a spherical coordinate system; the tangent vector of the starlight direction in the spherical coordinate system is as shown in the expression of the tangent vector of the starlight direction in the spherical coordinate system as described above. Convert the starlight tangent t in the spherical coordinate system into the Cartesian rectangular coordinate system, wherein the tangent vector of the starlight direction in the Cartesian rectangular coordinate system and the three-dimensional components of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system are respectively as shown in the expression of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system and the three-dimensional component expression of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system as described above; in the i-th update process, use the angle change amount of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system as the starlight refraction angle change amount, and sum up the starlight refraction angle change amounts in each starlight path update process to obtain the starlight refraction angle in the starlight path update.

[0084] In one embodiment, the starlight refraction angle change amount in the starlight refraction angle calculation module in the light path update is as shown in the expression of the starlight refraction angle change amount as described above.

[0085] For the specific limitations of the starlight refraction simulation device considering the three-dimensional refractive index distribution characteristics, reference can be made to the limitations of the starlight refraction simulation method considering the three-dimensional refractive index distribution characteristics in the foregoing text, which will not be elaborated herein. Each module in the above-mentioned starlight refraction simulation device considering the three-dimensional refractive index distribution characteristics can be implemented in whole or in part by software, hardware, and their combination. The above-mentioned modules can be embedded in the processor of the computer device in hardware form or be independent of it, or can be stored in the memory of the computer device in software form, so as to facilitate the processor to call and execute the operations corresponding to each of the above modules.

[0086] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0087] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics, characterized in that: The method comprises: Step S1: constructing a global atmospheric refraction index field through a global reanalysis data set at the current time according to the simulation scene time of the starlight atmospheric refraction navigation ground simulation system; Step S2: Calculate the refractive index at the interpolation point of interest in the starlight path update according to the global atmospheric refractive index field; Step S3: Calculate the refractive index gradients at the interpolation point of interest in the latitude, longitude and radial directions in the starlight path update according to the refractive index at the interpolation point of interest; Step S4: constructing a starlight refraction path model based on the three-dimensional eikonal equation, and using a numerical calculation method to calculate an update path of the starlight refraction path model based on the three-dimensional eikonal equation; wherein, during the update process, the update of the refractive index related variables is calculated according to step S2 and step S3; Step S5: Calculate the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process.

2. The method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics according to claim 1, characterized in that: Step S2 includes: calculating the refractive index at the interpolation point of interest in the starlight path update according to the global atmospheric refractive index field as: ； ； in, is the refractive index at the interpolation point of interest, is the refractive index of the underlying layer near the interpolation point of interest, k The layer is the lower layer that is adjacent to the interpolation point of interest. and Respectively k Layer and k +1 layer radial distance from the center of the Earth, i is the global atmospheric refractive index grid number near the interpolation point of interest; ; , , and are the radial distance, latitude and longitude from the center of the earth at the interpolation point of interest, respectively. and are the grid numbers of the global atmospheric refractive index near the interpolation point of interest. i The latitude and longitude of and are the grid numbers of the global atmospheric refractive index near the interpolation point of interest. i +1 latitude and longitude, is the refractive index function.

3. The method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics according to claim 1, characterized in that: Step S3 includes: according to the refractive index at the interpolation point of interest, calculating the refractive index gradient of the interpolation point of interest in the starlight path update in the latitude direction as: ； in, is the refractive index gradient in the latitude direction of the interpolation point of interest in the starlight path update, , , are the radial distance, latitude, and longitude from the center of the earth at the interpolation point of interest, respectively. , Respectively k Layer and k +1 layer radial distance from the center of the Earth, and are the radial distance and latitude of the starlight refraction point from the center of the earth during the numerical update process, is the refractive index function; According to the refractive index at the interpolation point of interest, the refractive index gradient of the interpolation point of interest in the longitude direction in the starlight path update is calculated as: ； in, is the refractive index gradient in the longitude direction of the interpolation point of interest in the starlight path update, It is the longitude of the starlight refraction point from the center of the earth during the value update process; According to the refractive index at the interpolation point of interest, the refractive index gradient of the interpolation point of interest in the radial direction in the starlight path update is calculated as: ； in, It is the refractive index gradient in the radial direction at the interpolation point of interest in the starlight path update.

4. The method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics according to claim 1, characterized in that: Step S4 includes: constructing a starlight refraction path model based on a three-dimensional eikonal equation: ； in, s is the length of the arc along the ray path, , and They are J The partial differential components in the radial, latitudinal and longitudinal directions, J is the light path length, , and are the radial distance, latitude and longitude of the starlight refraction point from the center of the earth during the numerical update process, is the refractive index function; Define the state vector , the starlight refraction path model based on the three-dimensional eikonal equation is converted into the form of the first-order derivative of the state vector, and the starlight refraction path is numerically updated using the fourth-order Runge-Kutta method.

5. The method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics according to claim 1, characterized in that: Step S5 includes: establishing a spherical coordinate system; the tangent vector of the starlight direction in the spherical coordinate system is: ； in, t is the tangent vector of the starlight direction in the spherical coordinate system, is the length of the arc along the ray path, , and They are the radial distance, latitude and longitude of the starlight refraction point from the center of the earth during the numerical update process; Convert the tangent vector of the starlight direction in the spherical coordinate system to the Cartesian rectangular coordinate system; the tangent vector of the starlight direction in the Cartesian rectangular coordinate system is: ； ； in, is the tangent vector of the starlight direction in the Cartesian rectangular coordinate system, are the three-dimensional components of the tangent vector to the starlight direction in the Cartesian rectangular coordinate system; In the i In the first updating process, the angle change of the tangent vector of the starlight direction in the Cartesian rectangular coordinate system is taken as the change of the starlight refraction angle; The changes in the starlight refraction angle during each starlight path update are summed to obtain the starlight refraction angle in the starlight path update.

6. The method for simulating starlight refraction taking into account the three-dimensional refractive index distribution characteristics according to claim 5, characterized in that: The change in the starlight refraction angle in the Cartesian rectangular coordinate system is: ； in, is the change in the starlight refraction angle, is the inverse tangent function, and Respectively i +1 time and i The tangent vector of the starlight direction in Cartesian coordinates during the update of the timestamp.

7. A starlight refraction simulation device taking into account the three-dimensional refractive index distribution characteristics, characterized in that: The device comprises: The global atmospheric refraction index field construction module is used to construct the global atmospheric refraction index field according to the simulation scene time of the starlight atmospheric refraction navigation ground simulation system and the global reanalysis data set of the current time; A refractive index calculation module at an interpolation point of interest, used to calculate the refractive index at an interpolation point of interest in starlight path updating according to the global atmospheric refractive index field; A refractive index gradient calculation module, used to calculate the refractive index gradient at the interpolation point of interest in the starlight path update in the latitude, longitude and radial directions according to the refractive index at the interpolation point of interest; A path update module for the starlight refraction path model based on the three-dimensional Eikonal equation is used to construct a starlight refraction path model based on the three-dimensional Eikonal equation, and to calculate the update path of the starlight refraction path model based on the three-dimensional Eikonal equation by a numerical calculation method; wherein, the update of the refractive index related variables in the updating process is calculated according to the refractive index calculation module and the refractive index gradient calculation module at the interpolation point of interest; The starlight refraction angle calculation module in the starlight path update is used to calculate the starlight refraction angle in the starlight path update according to the tangent method in the starlight refraction process.

8. The starlight refraction simulation device taking into account the three-dimensional refractive index distribution characteristics according to claim 7, characterized in that: The refractive index calculation module at the interpolation point of interest is also used to calculate the refractive index at the interpolation point of interest in the starlight path update according to the global atmospheric refractive index field: ； ； in, is the refractive index at the interpolation point of interest, is the refractive index of the lower layer near the interpolation point of interest, k The layer is the lower layer that is adjacent to the interpolation point of interest. and Respectively k Layer and k +1 layer radial distance from the center of the Earth, i is the global atmospheric refractive index grid number near the interpolation point of interest; ; , , and are the radial distance, latitude and longitude from the center of the earth at the interpolation point of interest, respectively. and are the grid numbers of the global atmospheric refractive index near the interpolation point of interest. i The latitude and longitude of and are the grid numbers of the global atmospheric refractive index near the interpolation point of interest. i Latitude and longitude at +1.

9. The starlight refraction simulation device taking into account the three-dimensional refractive index distribution characteristics according to claim 7, characterized in that: The refractive index gradient calculation module is further used to calculate the refractive index gradient of the interpolation point of interest in the latitude direction in the starlight path update according to the refractive index at the interpolation point of interest: ； in, is the refractive index gradient in the latitude direction of the interpolation point of interest in the starlight path update, and Respectively k Layer and k +1 layer radial distance from the center of the Earth, , and are the radial distance, latitude and longitude from the center of the earth at the interpolation point of interest, respectively. and They are the radial distance and latitude of the starlight refraction point from the center of the earth during the numerical update process; According to the refractive index at the interpolation point of interest, the refractive index gradient of the interpolation point of interest in the longitude direction in the starlight path update is calculated as: ； in, is the refractive index gradient in the longitude direction of the interpolation point of interest in the starlight path update, and They are respectively the radial distance and longitude of the starlight refraction point from the center of the earth during the numerical update process; According to the refractive index at the interpolation point of interest, the refractive index gradient of the interpolation point of interest in the radial direction in the starlight path update is calculated as: ； in, It is the refractive index gradient in the radial direction at the interpolation point of interest in the starlight path update.

10. The starlight refraction simulation device taking into account the three-dimensional refractive index distribution characteristics according to claim 7, characterized in that: The path update module of the starlight refraction path model based on the three-dimensional Eikonal equation is also used to construct the starlight refraction path model based on the three-dimensional Eikonal equation: ； in, s is the length of the arc along the ray path; , and They are J Partial differential components in radial, latitudinal and longitudinal directions; J is the light path length, , , They are the radial distance, latitude, and longitude of the starlight refraction point from the center of the earth during the numerical update process. It is the refraction index at the starlight refraction point during the value update process; Define the state vector , the starlight refraction path model based on the three-dimensional eikonal equation is converted into the form of the first-order derivative of the state vector, and the starlight refraction path is numerically updated using the fourth-order Runge-Kutta method.

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