A method for measuring near-space weather data based on an expanding falling ball

Abstract

The present invention provides a near-space meteorological data measurement method based on an expanding falling ball, which relates to the field of data measurement technology. The method comprises the following steps: S1, obtaining initial position point data of the falling ball in a station-centered coordinate system, and preprocessing the initial position point data to obtain standard position point data; S2, fitting the standard position point data to obtain initial fitting position point data, and obtaining falling ball velocity data based on the initial fitting position point data; S3, obtaining a vortex street period based on the falling ball velocity data; S4, judging the vortex street period and determining a final fitting time length; S5, obtaining the final fitting position point data and obtaining wind speed data, wind direction data, air pressure data, and temperature data. The present invention reduces the sideslip deviation caused by the vortex street in the airflow behind the falling ball, thereby improving the quality of meteorological data.

Description

Technical Field

[0001] The present invention relates to the field of data measurement technology, and in particular to a near-space weather data measurement method based on an expanding falling sphere. Background Art

[0002] The expansion falling ball technology is an intuitive and low-cost means of measuring near-space meteorological elements. Based on the principle of mechanical equilibrium, the atmospheric density, wind speed, and wind direction are analyzed by the time and space coordinates of the falling ball, and the ideal gas state equation is used to obtain the air pressure and temperature.

[0003] The existing method of obtaining meteorological data by the falling ball method is to release a sounding ball from a high altitude, record its time and space coordinates, analyze the atmospheric density, wind speed and wind direction, and then use the ideal gas state equation to obtain the air pressure and temperature. However, this method often ignores the influence of the vortex street phenomenon. The vortex street phenomenon refers to the vortices generated alternately on both sides of the object when the fluid flows around a non-streamlined object. These vortices will cause the flow field around the ball to be uneven, thereby causing velocity measurement errors and trajectory deviations. Specifically, the lateral force generated by the vortex street will cause the trajectory of the ball to deviate, causing the judgment of wind speed and wind direction. The vortex street will reduce the signal-to-noise ratio of the data, affecting the reliability and accuracy of the data. Summary of the Invention

[0004] The purpose of the present invention is to provide a near-space meteorological data measurement method based on an expanding falling ball, which weakens the sideslip deviation caused by the vortex street of the airflow behind the falling ball.

[0005] A method for measuring near-space weather data based on an expanding falling ball comprises the following steps:

[0006] S1. Obtain the initial position point data of the falling ball in the station center coordinate system, and pre-process the initial position point data to obtain standard position point data;

[0007] S2. Obtaining an initial number of fitting points based on the initial fitting time length and the sampling frequency; fitting the standard position point data using the least squares method to obtain initial fitting position point data, and obtaining falling ball velocity data based on the initial fitting position point data;

[0008] S3. Obtain vortex cycle based on falling ball velocity data:

[0009] ;

[0010] Where: is the diameter of the falling ball; is the initial falling ball velocity; , is the initial X-axis fitting coordinate, obtained based on the initial X-axis fitting coordinate point data; is the initial Y-axis fitting coordinate, obtained based on the initial Y-axis fitting coordinate point data; is the initial Z-axis fitting coordinate, obtained based on the initial Z-axis fitting coordinate point data; represents the derivative; is the vortex period; is the Reynolds number;

[0011] S4. Determine the vortex cycle and determine the final fitting time length. If , then As the final fitting time length; if , then As the final fitting time length, is the length of initial fitting time, n is a positive integer greater than or equal to 2;

[0012] S5. Based on the final fitting time length and the sampling frequency, a final number of fitting points is obtained, and the standard position point data is fitted based on the final number of fitting points to obtain the final fitting position point data. Wind speed data, wind direction data, air pressure data, and temperature data are obtained according to the final fitting position point data.

[0013] Preferably, in S1, the standard position point data includes standard X-axis coordinate point data, standard Y-axis coordinate point data and standard Z-axis coordinate point data; the origin O of the station center coordinate system is the intersection of the horizontal rotation axis and the vertical rotation axis of the observation instrument, the X-axis points to due north, the Y-axis points to due east, and the Z-axis passes through the origin and is perpendicular to the XOY plane and points to the zenith.

[0014] Preferably, in S2, the initial fitting position point data includes initial X-axis fitting coordinate point data, initial Y-axis fitting coordinate point data and initial Z-axis fitting coordinate point data, and the final fitting position point data in S5 includes final X-axis fitting coordinate point data, final Y-axis fitting coordinate point data and final Z-axis fitting coordinate point data.

[0015] Preferably, S1 includes:

[0016] S11, obtaining the initial position point data of the falling ball in the station center coordinate system and performing interpolation processing to obtain the initial standard position point data;

[0017] S12, obtaining a correction fitting time length according to the initial standard Z-axis coordinate point data, obtaining a correction fitting point number based on the correction fitting time length and the sampling frequency, and obtaining initial fitting coordinate point data after fitting;

[0018] S13. Based on the initial fitting coordinate point data, the 3σ method is used to remove abnormal values ​​in the initial fitting coordinate point data and then interpolation processing is performed to obtain standard position point data.

[0019] Preferably, the initial fitting time length and the initial fitting point number in S2 are expressed as:

[0020] ;

[0021] ;

[0022] in, is the resolution of the height of the falling ball, is the theoretical average falling speed of the falling ball at the height, is the initial fitting time length, is the number of initial fitting points, is the sampling frequency, Indicates rounding up to the nearest odd number.

[0023] Preferably, obtaining wind speed data, wind direction data, air pressure data and temperature data according to the final fitting position point data in S5 includes the following steps:

[0024] S51, obtaining X-axis velocity data, X-axis acceleration data, Y-axis velocity data, Y-axis acceleration data, Z-axis velocity data, and Z-axis acceleration data according to the final fitting position point data;

[0025] S52, based on S51, obtain atmospheric density data, X-axis wind speed data, and Y-axis wind speed data, and calculate a judgment coefficient;

[0026] S53, obtaining wind speed data and wind direction data based on the X-axis wind speed data and the Y-axis wind speed data;

[0027] S54. Obtain air pressure data based on the atmospheric density data, and obtain temperature data based on the air pressure data and the atmospheric density data.

[0028] Preferably, the atmospheric density data, X-axis wind speed data, and Y-axis wind speed data in S52 are expressed as follows:

[0029] ;

[0030] Where, is the atmospheric density data, is the X-axis wind speed data, is the Y-axis wind speed data, is the Z-axis wind speed data, , is the average radius of the earth, m is the mass of the falling ball, is the acceleration due to gravity at zero altitude, is the altitude of the origin of the station center coordinate system, is the Z-axis acceleration, is the X-axis speed, is the Y-axis speed, is the Z-axis speed, is the X-axis acceleration, is the Y-axis acceleration, is the X-axis angular velocity, is the Y-axis angular velocity, is the Z-axis angular velocity, is the air resistance coefficient, is the cross-sectional area of ​​the falling ball, is the volume of the falling ball, x is the final X-axis fitting coordinate, which is obtained by the final X-axis fitting coordinate point data, and y is the final Y-axis fitting coordinate, which is obtained by the final Y-axis fitting coordinate point data.

[0031] Preferably, the judgment coefficient in S52 The expression is:

[0032] ;

[0033] Where, is the judgment coefficient, z is the final Z-axis fitting coordinate, The atmospheric density corresponding to the final Z-axis fitting coordinate;

[0034] To judge the judgment coefficient, ≤ ≤ When , return to S1, when or When S53 is executed, The distance that the Z-axis speed corresponding to the final Z-axis fitting coordinate moves in 1s.

[0035] Preferably, the wind speed data expression in S53 is:

[0036] ;

[0037] The wind direction data expression is:

[0038] ;

[0039] Where, Indicates wind speed data, G indicates wind direction data, is the X-axis wind speed data, Y-axis wind speed data.

[0040] Preferably, the expressions of the air pressure data and temperature data in S54 are respectively:

[0041] ;

[0042] ;

[0043] Where, The altitude is Atmospheric pressure data at is the air pressure data of the origin of the station center coordinate system, is the atmospheric density data, is the gravitational acceleration of the origin of the station center coordinate system, is the altitude of the origin of the station center coordinate system, is the altitude of the i-th ball landing position, The altitude is Atmospheric density data at time is the atmospheric density data of the origin of the station center coordinate system, is the average radius of the Earth, , is the sea level gravity acceleration at the station center, is the final Z-axis fitting coordinate of the i-th ball falling position, is the calibration value of the earth radius at sea level at the station center, is the standard acceleration due to gravity; The altitude is Temperature data at is the gas constant for clean dry air.

[0044] The effects of the present invention are as follows:

[0045] The present invention is based on a near-space meteorological data measurement method of an expanding falling ball, obtains the vortex street period, regards the data segment of one period as a whole, fits the data within one period to extract the main trend, and filters out the high-frequency fluctuations caused by the vortex street, thereby improving the accuracy and reliability of data processing, thereby reducing the impact of the vortex street, and can effectively reduce the impact of the vortex street on velocity measurement and trajectory deviation, thereby improving the quality of meteorological data.

[0046] The present invention is based on the near-space meteorological data measurement method of the expanding falling ball, and adds a data validity check. By comparing the actual falling speed corresponding to the coordinates of the inflection point with the theoretical average falling speed, it can preliminarily determine whether the sphere is broken or collapsed, thereby preliminarily obtaining the validity of the data and avoiding the subsequent calculation process caused by huge defects in the data. Further, by introducing the judgment coefficient , to finally determine whether the sphere is broken or collapsed, and thus actually determine the validity of the data. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of the method for measuring near-space weather data based on an expanding falling ball according to the present invention;

[0048] Figure 2 This is a schematic diagram of the drag coefficient of the ROBIN ball. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0050] like Figure 1 As shown, the present invention provides a method for measuring near-space weather data based on an expanding falling ball, which includes:

[0051] S1. Obtain the initial position data of the falling ball in the station-centered coordinate system and preprocess the initial position data to obtain standard position data. The standard position data includes standard X-axis coordinate data, standard Y-axis coordinate data, and standard Z-axis coordinate data. The origin O of the station-centered coordinate system is the intersection of the horizontal and vertical rotation axes of the observation instrument. The X-axis points due north, the Y-axis points due east, and the Z-axis passes through the origin and is perpendicular to the XOY plane and points to the zenith.

[0052] Specifically, S1 includes:

[0053] S11. Obtain the initial position point data of the falling ball in the station center coordinate system and perform interpolation processing to obtain the initial standard position point data.

[0054] The initial position point data includes initial X-axis coordinate point data, initial Y-axis coordinate point data, and initial Z-axis coordinate point data.

[0055] Interpolation processing is performed on the missing data in the initial position point data to obtain interpolated data; the interpolated data includes X-axis coordinate point interpolation data, Y-axis coordinate point interpolation data and Z-axis coordinate point interpolation data.

[0056] After removing the error data in the interpolation data, interpolation processing is performed to obtain initial standard position point data; the initial standard position point data includes initial standard X-axis coordinate point data, initial standard Y-axis coordinate point data and initial standard Z-axis coordinate point data.

[0057] The sounding code output by the observation instrument will perform a check code calculation on the sounding meteorological data bytes and output a check code field. When this field is 1, it means that a byte has changed during the transmission process and interference has occurred during the sending process, resulting in inconsistency between the actual received data and the sent data. For this set of data, the method is to eliminate it and then interpolate and fill in the points.

[0058] For example, the sounding code bytes 9-24 contain sounding data, including time, longitude, latitude, and altitude. The checksum is generated by summing these bytes and running them through CRC-16. This checksum is then output to the end of the sounding code. This method can be used to determine the validity of normal sounding data, but when it is subject to interference from the receiving environment or during transmission, further validation can be performed.

[0059] S12. Obtain a correction fitting time length according to the initial standard Z-axis coordinate point data, obtain a correction fitting point number based on the correction fitting time length and the sampling frequency, and obtain initial fitting coordinate point data after fitting.

[0060] The initial standard X-axis coordinate point data, the initial standard Y-axis coordinate point data and the initial standard Z-axis coordinate point data are fitted based on the corrected fitting point number to obtain the initial fitting coordinate point data, namely the initial X-axis fitting coordinate point data, the initial Y-axis fitting coordinate point data and the initial Z-axis fitting coordinate point data.

[0061] S13. Based on the initial X-axis fitting coordinate point data, the initial Y-axis fitting coordinate point data, and the initial Z-axis fitting coordinate point data, the 3σ method is used to remove outliers in the initial fitting coordinate point data and then interpolation processing is performed to obtain standard position point data, namely, standard X-axis coordinate point data, standard Y-axis coordinate point data, and standard Z-axis coordinate point data.

[0062] The 3σ method expression is:

[0063] ;

[0064] Where: is the standard deviation, n is the number of correction fitting points, is the i-th initial standard X-axis coordinate point among the n initial standard X-axis coordinate point data, for After fitting, the value <3 and >-3 = ,otherwise = .

[0065] Preferably, after S11, the method further includes:

[0066] The coordinates of the inflection point of the falling ball and the Z-axis falling speed data are obtained based on the initial Z-axis coordinate point data. The inflection point of the falling ball is the point where the Z-axis acceleration of the falling ball is zero.

[0067] When the Z-axis coordinate corresponding to the Z-axis falling speed is greater than or equal to the coordinate of the inflection point, the Z-axis falling speed is judged. When the difference between the Z-axis falling speed and the theoretical average falling speed corresponding to the Z-axis coordinate is greater than the first set threshold, the initial position point data is discarded and returned to S11. When the difference between the Z-axis falling speed and the theoretical average falling speed corresponding to the Z-axis coordinate is less than or equal to the first set threshold, S12 is executed.

[0068] When the Z-axis coordinate corresponding to the Z-axis falling speed is less than the coordinate of the inflection point, the Z-axis falling speed is judged. When the difference between the Z-axis falling speed and the theoretical average falling speed corresponding to the Z-axis coordinate is greater than the second set threshold, the initial position point data is discarded and returned to S11. When the difference between the Z-axis falling speed and the theoretical average falling speed corresponding to the Z-axis coordinate is less than or equal to the second set threshold, S12 is executed; the first set threshold is greater than the second set threshold.

[0069] S2. Obtain an initial fitting point number based on the initial fitting time length and the sampling frequency; use the least squares method to fit the standard position point data to obtain initial fitting position point data, and obtain falling ball velocity data based on the initial fitting position point data.

[0070] According to the standard Z-axis coordinate point data, the initial fitting time length is obtained, and the initial fitting point number is obtained based on the initial fitting time length and the sampling frequency.

[0071] Preferably, the initial fitting time length expression is:

[0072] ;

[0073] Where: is the resolution of the height of the falling ball, is the theoretical average falling speed of the falling ball at the height, is the initial fitting time length.

[0074] The expression for the initial fitting points is:

[0075] ;

[0076] Where: is the number of initial fitting points, is the sampling frequency, Indicates rounding up to the nearest odd number.

[0077] Based on the initial fitting point number, the least squares method is used to fit the standard X-axis coordinate point data, the standard Y-axis coordinate point data, and the standard Z-axis coordinate point data to obtain the initial fitting position point data, namely the initial X-axis fitting coordinate point data, the initial Y-axis fitting coordinate point data, and the initial Z-axis fitting coordinate point data.

[0078] The falling ball velocity data is obtained based on the initial X-axis fitting coordinate point data, the initial Y-axis fitting coordinate point data, and the initial Z-axis fitting coordinate point data.

[0079] S3. Obtain the vortex period based on the falling ball velocity data. The expression is:

[0080] ;

[0081] Where: is the diameter of the falling ball, is the initial falling ball velocity, , is the initial X-axis fitting coordinate, obtained based on the initial X-axis fitting coordinate point data, is the initial Y-axis fitting coordinate, obtained based on the initial Y-axis fitting coordinate point data, is the initial Z-axis fitting coordinate, obtained based on the initial Z-axis fitting coordinate point data, represents the derivation, is the vortex period, is the Reynolds number, when or When , there is no vortex street.

[0082] S4. Determine the vortex cycle and determine the final fitting time length. , then As the final fitting time length; if , then As the final fitting time length, is the length of the initial fitting time, and n is a positive integer greater than or equal to 2.

[0083] S5. Based on the final fitting time length and the sampling frequency, a final number of fitting points is obtained. Based on the final number of fitting points, the standard position point data, i.e., the standard X-axis coordinate point data, the standard Y-axis coordinate point data, and the standard Z-axis coordinate point data, are fitted to obtain final fitting position point data. The final fitting position point data is the final X-axis fitting coordinate point data, the final Y-axis fitting coordinate point data, and the final Z-axis fitting coordinate point data. In a specific embodiment, the specific fitting process is as follows:

[0084] First, the final number of fitting points is obtained based on the final fitting time length and sampling frequency. Then, the standard position point data, namely the standard X-axis coordinate point data, the standard Y-axis coordinate point data, and the standard Z-axis coordinate point data, are fitted based on the final number of fitting points.

[0085] During the fitting process, the standard X-axis coordinate point data, the standard Y-axis coordinate point data, and the standard Z-axis coordinate point data are first smoothed to obtain the smoothed data of the standard X-axis coordinate point data, the standard Y-axis coordinate point data, and the standard Z-axis coordinate point data. Then, based on the final number of fitting points, the smoothed data of the standard X-axis coordinate point data and the standard Y-axis coordinate point data are fitted to obtain the final X-axis fitting coordinate point data and the final Y-axis fitting coordinate point data.

[0086] When fitting the standard Z-axis coordinate point data, the least squares method is used to fit the standard Z-axis coordinate point data based on the final number of fitting points to obtain preliminary final Z-axis fitting coordinate point data. After obtaining the preliminary final Z-axis fitting coordinate point data, the preliminary final Z-axis fitting coordinate point data is judged. If the difference between the preliminary final Z-axis fitting coordinate point data and the smoothed data of the standard Z-axis coordinate point data is greater than a set threshold, the final Z-axis fitting coordinate point data is discarded and the standard Z-axis coordinate point data is re-processed with moving average smoothing. If the difference between the final Z-axis fitting coordinate point data and the smoothed data of the standard Z-axis coordinate point data is less than or equal to the set threshold, the final Z-axis fitting coordinate point data is used as the final Z-axis fitting coordinate point data.

[0087] Then, wind speed data, wind direction data, air pressure data and temperature data are obtained according to the final fitting position point data. The specific steps are as follows:

[0088] S51 . Obtain X-axis velocity data, X-axis acceleration data, Y-axis velocity data, Y-axis acceleration data, Z-axis velocity data, and Z-axis acceleration data according to the final fitting position point data.

[0089] The X-axis velocity data and X-axis acceleration data are obtained based on the final X-axis fitting coordinate point data, the Y-axis velocity data and Y-axis acceleration data are obtained based on the final Y-axis fitting coordinate point data, and the Z-axis velocity data and Z-axis acceleration data are obtained based on the final Z-axis fitting coordinate point data.

[0090] Specifically, the final X-axis fitting coordinate point data is first-order differentiated to obtain X-axis velocity data, and the X-axis velocity data is first-order differentiated after cubic fitting to obtain X-axis acceleration data.

[0091] The final Y-axis fitting coordinate point data is first-order differentiated to obtain the Y-axis velocity data. The Y-axis velocity data is fitted with a cubic term and then first-order differentiated to obtain the Y-axis acceleration data.

[0092] The Z-axis velocity data is obtained by performing a first-order derivative on the final Z-axis fitting coordinate point data. The Z-axis velocity data is fitted with a cubic term and then first-order differentiated to obtain the Z-axis acceleration data.

[0093] S52. Based on S51, obtain atmospheric density data, X-axis wind speed data, and Y-axis wind speed data, and calculate a judgment coefficient.

[0094] Based on the X-axis velocity data, X-axis acceleration data, Y-axis velocity data, Y-axis acceleration data, Z-axis velocity data, and Z-axis acceleration data, the atmospheric density data, X-axis wind speed data, and Y-axis wind speed data are obtained. The expression is:

[0095] ;

[0096] Where: is the atmospheric density data, is the X-axis wind speed data, is the Y-axis wind speed data, is the Z-axis wind speed data, , is the average radius of the earth, m is the mass of the falling ball, is the acceleration due to gravity at zero altitude, is the altitude of the origin of the station center coordinate system, is the Z-axis acceleration, is the X-axis speed, is the Y-axis speed, is the Z-axis speed, is the X-axis acceleration, is the Y-axis acceleration, is the X-axis angular velocity, is the Y-axis angular velocity, is the Z-axis angular velocity, is the air resistance coefficient, is the cross-sectional area of ​​the falling ball, is the volume of the falling ball, x is the final X-axis fitting coordinate, obtained by the final X-axis fitting coordinate point data, y is the final Y-axis fitting coordinate, obtained by the final Y-axis fitting coordinate point data, and the drag coefficient It is the key parameter for falling ball detection. Currently, the main parameters available are Figure 2 As shown in the ROBIN ball drag curve, when the ball falls to a lower height, the falling ball speed becomes subsonic, and its drag coefficient is Figure 2 The subsonic data shown has good consistency. However, the change of the drag coefficient in the transonic section is more complicated. The drag coefficient in the low altitude section below 2.5M is adopted. To calculate.

[0097] Calculate the judgment coefficient based on the atmospheric density data and the final Z-axis fitting coordinate point data , the expression is:

[0098] ;

[0099] Where, is the judgment coefficient, z is the final Z-axis fitting coordinate, The atmospheric density corresponding to the final Z-axis fitting coordinate;

[0100] To judge the judgment coefficient, ≤ ≤ When , return to S1, when or When S53 is executed, The distance that the Z-axis speed corresponding to the final Z-axis fitting coordinate moves in 1s.

[0101] S53 . Obtain wind speed data and wind direction data based on the X-axis wind speed data and the Y-axis wind speed data.

[0102] The wind speed data expression is:

[0103] .

[0104] The wind direction data expression is:

[0105] .

[0106] Where: Indicates wind speed data, G indicates wind direction data, is the X-axis wind speed data, Y-axis wind speed data.

[0107] Since the X-axis of the station center coordinate system points to due north, the Y-axis points to due east, and the Z-axis passes through the origin and is perpendicular to the XOY plane and points to the zenith, the X-axis wind speed is the longitudinal wind speed, the Y-axis wind speed is the latitudinal wind speed, and the Z-axis wind speed is the vertical wind speed. W is the synthetic wind speed data.

[0108] S54: Obtain air pressure data based on the atmospheric density data, and obtain temperature data based on the air pressure data and the atmospheric density data. Specific expressions for the air pressure data and the temperature data are shown below.

[0109] The air pressure data expression is:

[0110] .

[0111] Where: The altitude is Atmospheric pressure data at is the air pressure data of the origin of the station center coordinate system, is the atmospheric density data, is the gravitational acceleration of the origin of the station center coordinate system, is the altitude of the origin of the station center coordinate system, is the altitude of the i-th ball landing position, obtained according to the final Z-axis fitting coordinate point data, The altitude is Atmospheric density data at time is the atmospheric density data of the origin of the station center coordinate system, is the average radius of the Earth, , is the sea level gravity acceleration at the station center, is the final Z-axis fitting coordinate of the i-th ball falling position, obtained through the final Z-axis fitting coordinate point data, is the calibration value of the earth radius at sea level at the station center, is the standard acceleration due to gravity.

[0112] The temperature data expression is:

[0113] .

[0114] Where: The altitude is Temperature data at is the gas constant for clean dry air.

[0115] The above embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for measuring near-space weather data based on an expanding falling ball, characterized in that: It includes: S1. Obtain the initial position point data of the falling ball in the station center coordinate system, and pre-process the initial position point data to obtain standard position point data; S2. Obtaining an initial number of fitting points based on the initial fitting time length and the sampling frequency; fitting the standard position point data using the least squares method to obtain initial fitting position point data, and obtaining falling ball velocity data based on the initial fitting position point data; S3. Obtain vortex cycle based on falling ball velocity data: ； Where: is the diameter of the falling ball; is the initial falling ball velocity; , is the initial X-axis fitting coordinate, obtained based on the initial X-axis fitting coordinate point data; is the initial Y-axis fitting coordinate, obtained based on the initial Y-axis fitting coordinate point data; is the initial Z-axis fitting coordinate, obtained based on the initial Z-axis fitting coordinate point data; represents the derivative; is the vortex period; is the Reynolds number; S4. Determine the vortex cycle and determine the final fitting time length. If , then As the final fitting time length; if , then As the final fitting time length, is the length of initial fitting time, n is a positive integer greater than or equal to 2; S5. Based on the final fitting time length and the sampling frequency, a final number of fitting points is obtained, and the standard position point data is fitted based on the final number of fitting points to obtain the final fitting position point data. Wind speed data, wind direction data, air pressure data, and temperature data are obtained according to the final fitting position point data.

2. The method for measuring near-space weather data based on an expanding falling ball according to claim 1, characterized in that: In S1, the standard position point data includes standard X-axis coordinate point data, standard Y-axis coordinate point data, and standard Z-axis coordinate point data; the origin O of the station center coordinate system is the intersection of the horizontal rotation axis and the vertical rotation axis of the observation instrument, the X-axis points to due north, the Y-axis points to due east, and the Z-axis passes through the origin and is perpendicular to the XOY plane and points to the zenith.

3. The method for measuring near-space weather data based on an expanding falling ball according to claim 2, characterized in that: In S2, the initial fitting position point data includes initial X-axis fitting coordinate point data, initial Y-axis fitting coordinate point data and initial Z-axis fitting coordinate point data, and the final fitting position point data in S5 includes final X-axis fitting coordinate point data, final Y-axis fitting coordinate point data and final Z-axis fitting coordinate point data.

4. The method for measuring near-space weather data based on an expanding falling ball according to claim 1, characterized in that: S1 includes: S11, obtaining the initial position point data of the falling ball in the station center coordinate system and performing interpolation processing to obtain the initial standard position point data; S12, obtaining a correction fitting time length according to the initial standard Z-axis coordinate point data, obtaining a correction fitting point number based on the correction fitting time length and the sampling frequency, and obtaining initial fitting coordinate point data after fitting; S13. Based on the initial fitting coordinate point data, the 3σ method is used to remove abnormal values ​​in the initial fitting coordinate point data and then interpolation processing is performed to obtain standard position point data.

5. The method for measuring near-space weather data based on an expanding falling ball according to claim 1, characterized in that: The expressions for the initial fitting time length and the initial fitting points in S2 are: ； ； in, is the resolution of the height of the falling ball, is the theoretical average falling speed of the falling ball at the height, is the initial fitting time length, is the number of initial fitting points, is the sampling frequency, Indicates rounding up to the nearest odd number.

6. The method for measuring near-space weather data based on an expanding falling ball according to claim 3, characterized in that: In S5, wind speed data, wind direction data, air pressure data, and temperature data are obtained based on the final fitting position point data, including the following steps: S51, obtaining X-axis velocity data, X-axis acceleration data, Y-axis velocity data, Y-axis acceleration data, Z-axis velocity data, and Z-axis acceleration data according to the final fitting position point data; S52, based on S51, obtain atmospheric density data, X-axis wind speed data, and Y-axis wind speed data, and calculate a judgment coefficient; S53, obtaining wind speed data and wind direction data based on the X-axis wind speed data and the Y-axis wind speed data; S54. Obtain air pressure data based on the atmospheric density data, and obtain temperature data based on the air pressure data and the atmospheric density data.

7. The method for measuring near-space weather data based on an expanding falling ball according to claim 6, characterized in that: The expressions of atmospheric density data, X-axis wind speed data and Y-axis wind speed data in S52 are: ； Where, is the atmospheric density data, is the X-axis wind speed data, is the Y-axis wind speed data, is the Z-axis wind speed data, , is the average radius of the earth, m is the mass of the falling ball, is the acceleration due to gravity at zero altitude, is the altitude of the origin of the station center coordinate system, is the Z-axis acceleration, is the X-axis speed, is the Y-axis speed, is the Z-axis speed, is the X-axis acceleration, is the Y-axis acceleration, is the X-axis angular velocity, is the Y-axis angular velocity, is the Z-axis angular velocity, is the air resistance coefficient, is the cross-sectional area of ​​the falling ball, is the volume of the falling ball, x is the final X-axis fitting coordinate, which is obtained by the final X-axis fitting coordinate point data, and y is the final Y-axis fitting coordinate, which is obtained by the final Y-axis fitting coordinate point data.

8. The method for measuring near-space weather data based on an expanding falling ball according to claim 7, characterized in that: Judgment coefficient in S52 The expression is: ； Where, is the judgment coefficient, z is the final Z-axis fitting coordinate, The atmospheric density corresponding to the final Z-axis fitting coordinate; To judge the judgment coefficient, ≤ ≤ When , return to S1, when or When S53 is executed, The distance that the Z-axis speed corresponding to the final Z-axis fitting coordinate moves in 1s.

9. The method for measuring near-space weather data based on an expanding falling ball according to claim 8, characterized in that: The wind speed data expression in S53 is: ； The wind direction data expression is: ； Where, represents wind speed data, G represents wind direction data, is the X-axis wind speed data, Y-axis wind speed data.

10. The method for measuring near-space weather data based on an expanding falling ball according to claim 9, characterized in that: The expressions for pressure data and temperature data in S54 are: ； ； Where, The altitude is Atmospheric pressure data at is the air pressure data of the origin of the station center coordinate system, is the atmospheric density data, is the gravitational acceleration of the origin of the station center coordinate system, is the altitude of the origin of the station center coordinate system, is the altitude of the i-th ball landing position, The altitude is Atmospheric density data at time is the atmospheric density data of the origin of the station center coordinate system, is the average radius of the Earth, , is the sea level gravity acceleration at the station center, is the final Z-axis fitting coordinate of the i-th ball falling position, is the calibration value of the earth radius at sea level at the station center, is the standard acceleration due to gravity; The altitude is Temperature data at is the gas constant for clean dry air.

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