CN-121995116-A - Ionosphere electron density profile abnormal fluctuation detection method, system and equipment

CN121995116ACN 121995116 ACN121995116 ACN 121995116ACN-121995116-A

Abstract

A method for detecting abnormal fluctuation of ionosphere electron density profile includes calculating relative electron density change rate between adjacent height points of each effective electron density profile, dividing height axes into a plurality of sections, counting steady percentile indexes of relative electron density change rate in each height section for each effective electron density profile, generating noise upper limit threshold, sawtooth amplitude threshold and extreme abrupt change threshold, formulating three-level progressive judging flow comprising high noise background criterion, extreme single-point jump criterion and effective sawtooth structure criterion based on the noise upper limit threshold, the extreme abrupt change threshold and the sawtooth amplitude threshold, and judging that the electron density profile is invalid if any criterion is triggered. The invention can efficiently and accurately identify the non-physical sawtooth oscillation and the extreme jump, and remarkably improve the quality control capability of data before ionosphere modeling.

Inventors

LI MIN
ZHANG WENYAO
ZHANG TING
YUAN YUNBIN
HUO XINGLIANG
SHENG CHUNCHUN
SUN WEIHONG

Assignees

中国科学院精密测量科学与技术创新研究院

Dates

Publication Date: 20260508
Application Date: 20251211

Claims (10)

1. An ionospheric electron density profile anomaly fluctuation detection method, characterized by comprising: calculating the relative electron density change rate between adjacent height points of each effective electron density profile; Dividing a height axis into a plurality of intervals, and counting a steady percentile index of a relative electron density change rate in each height interval for each effective electron density profile to generate a noise upper limit threshold, a sawtooth amplitude threshold and an extreme abrupt change threshold; And formulating a three-level progressive judging process comprising a high noise background criterion, an extreme single-point jump criterion and an effective sawtooth structure criterion based on the noise upper limit threshold, the extreme abrupt change threshold and the sawtooth amplitude threshold, and judging that the electron density profile is invalid if any one criterion is triggered.
2. The method for detecting abnormal fluctuation of ionospheric electron density profile according to claim 1, wherein the method for calculating the relative electron density change rate comprises: for each effective electron density profile, calculating the absolute value of electron density between adjacent height points: ; in the formula, Is the absolute difference of electron density; Is a height point Electron density of (a); Is a height point Electron density of (a); Based on the normalization of the electron density smaller values in the two adjacent points, the relative electron density change rate is obtained: ; in the formula, Is the rate of change of the relative electron density.
3. The method of claim 1, wherein the step of generating noise upper threshold, saw tooth amplitude threshold and extreme abrupt threshold by counting a robust percentile indicator of a rate of change of relative electron density in each altitude interval comprises: And counting 75 th percentile, 95 th percentile and maximum value of the relative electron density change rate in each altitude interval to respectively obtain first statistics, second statistics and third statistics, summarizing the first statistics, the second statistics and the third statistics of all electron density profiles in the same altitude interval, obtaining a sawtooth amplitude threshold value by taking the 75 th percentile of the first statistics, obtaining a noise upper limit threshold value by taking the 75 th percentile of the second statistics, and obtaining an extreme mutation threshold value by multiplying the 75 th percentile of the third statistics by 1.2.
4. The method for detecting abnormal fluctuation of ionospheric electron density profile according to claim 1, wherein the high noise background criterion is: statistics of the ratio of the relative electron density change rate to the noise upper threshold : ; In the formula, Is the relative electron density change rate; Is a height point A noise upper threshold of (2); The total number of data points in the electron density profile data; if the ratio exceeds the preset threshold, the whole electron density profile is polluted by high-frequency noise, and the electron density profile is judged to be invalid.
5. The method for detecting abnormal fluctuation of ionospheric electron density profile according to claim 1, wherein the extreme single-point jump criterion is: if more than two height points exist in the effective height interval, the following conditions are satisfied: ; in the formula, Is the relative electron density change rate; Is a height point Is a threshold for extreme mutation; it is indicated that the electron density profile contains a non-physical abrupt change and the electron density profile is determined to be ineffective.
6. The method for detecting abnormal fluctuation of ionospheric electron density profile according to claim 1, wherein the effective sawtooth structure criterion is: Calculating the sign change of the electron density difference sequence, and positioning potential sawtooth vertexes; for each symbol turning point, if at least one of two adjacent relative electron density change rates in front and back is not lower than a sawtooth amplitude threshold value, the symbol turning point is an effective sawtooth vertex; And counting the maximum continuous length of the effective sawtooth peak, and if the maximum continuous length is greater than or equal to a set threshold value, indicating that the electron density profile has systematic and non-physical periodic oscillation, and judging that the electron density profile has sawtooth abnormality.
7. The method for detecting abnormal fluctuation of ionospheric electron density profile according to claim 6, wherein the method for determining potential zigzag vertices is as follows: given electron density profile Corresponding height The first-order difference between adjacent height points is calculated as: ; in the formula, Is the electron density variation between two adjacent height points; Is a height point Electron density of (a); Is a height point Electron density of (a); extracting differential symbol sequences : ; Calculating the difference of the symbol sequences : ; If it is Then describe at the height point Here, the trend of change in electron density is reversed: If the differential symbol sequence is from +1 to-1, the altitude point is described Is a local maximum point; If the differential symbol sequence is from-1 to +1, the altitude point is described Is a local minimum point; The positions of the local maximum value points and the local minimum value points are potential saw-tooth vertexes.
8. An ionospheric electron density profile anomaly fluctuation detection system for implementing the method of any of claims 1 to 7, the system comprising: the relative electron density change rate acquisition module is used for calculating the relative electron density change rate between adjacent height points of each effective electron density profile; The dynamic threshold value acquisition module is used for dividing the height axis into a plurality of sections, counting a steady percentile index of a relative electron density change rate in each height section aiming at each effective electron density profile, and generating a noise upper limit threshold value, a sawtooth amplitude threshold value and an extreme abrupt change threshold value; the profile abnormality judging module is used for making a three-level progressive judging process comprising a high noise background criterion, an extreme single-point jump criterion and an effective sawtooth structure criterion based on the noise upper limit threshold value, the extreme abrupt change threshold value and the sawtooth amplitude threshold value, and judging that the electron density profile is invalid if any one of the criteria is triggered.
9. An ionosphere electron density profile abnormal fluctuation detection device is characterized in that, Comprising a memory and a processor; the memory is used for storing computer program codes and transmitting the computer program codes to the processor; The processor being configured to perform the method of any of claims 1 to 7 according to instructions in the computer program code.
10. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the method according to any of claims 1 to 7.

Description

Ionosphere electron density profile abnormal fluctuation detection method, system and equipment Technical Field The invention belongs to the technical field of space environment monitoring and data quality control, and particularly relates to a method, a system and equipment for detecting abnormal fluctuation of an ionosphere electron density profile. Background The ionosphere is used as a region with remarkable electromagnetic properties in the earth atmosphere, and the electron density distribution of the ionosphere has important influence on the application of radio wave propagation, satellite navigation, space weather monitoring and the like. Thus, accurate ionospheric electron density modeling has been a key element in spatial environment research and application. At present, ionosphere modeling mainly depends on fusion processing of various data sources such as ground observation (e.g. ionosphere altimeter, GNSS inversion) and space observation (e.g. radio occultation and satellite in-situ measurement). In theory, the true ionosphere electron density profile presents a smooth layered structure (e.g., E layer, F1 layer, F2 layer), and there is a large gradient near the peak region of the F2 layer, but the overall change is continuous and free of high frequency oscillations. However, in the actual observation or inversion process, due to factors such as instrument noise, signal multipath effect, unstable inversion algorithm value, etc., a non-physical "saw-tooth-like" abnormal profile, i.e. the electron density rises and falls rapidly and alternately with the height, is often generated, and a pseudo structure similar to saw teeth is formed. Such anomalies are not reflective of ionosphere real state, and if not effectively rejected and directly used for modeling, local ionosphere parameter distortion will result, and navigation positioning accuracy and space weather product reliability are significantly reduced. The existing quality control method mostly adopts global fixed threshold, smooth filtering or consistency check, and mainly aims at obvious outliers or overall trend deviation, and lacks a special recognition mechanism for the specific morphological abnormality of 'saw tooth shape'. In particular, in the F layer high gradient region, the fixed threshold value is easy to misjudge the normal physical structure as abnormal, and in the low density high layer region, weak detection but system oscillation noise may be missed. In the technical scheme disclosed at present, no special method for systematically identifying and eliminating the saw-tooth-shaped electron density profile exists. Therefore, a dynamic discrimination technique capable of adapting to physical characteristics of regions with different heights is needed to improve the intelligentization level and modeling robustness of ionosphere data preprocessing. Disclosure of Invention The invention aims to overcome the defects and problems in the prior art and provide a method, a system and equipment for detecting abnormal fluctuation of an ionosphere electron density profile, which can efficiently and accurately identify non-physical sawtooth oscillation and extreme jump and remarkably improve the quality control capability of data before ionosphere modeling. In order to achieve the above object, the technical solution of the present invention is: in a first aspect, the present invention provides a method for detecting abnormal fluctuation of ionosphere electron density profile, comprising: calculating the relative electron density change rate between adjacent height points of each effective electron density profile; Dividing a height axis into a plurality of intervals, and counting a steady percentile index of a relative electron density change rate in each height interval for each effective electron density profile to generate a noise upper limit threshold, a sawtooth amplitude threshold and an extreme abrupt change threshold; And formulating a three-level progressive judging process comprising a high noise background criterion, an extreme single-point jump criterion and an effective sawtooth structure criterion based on the noise upper limit threshold, the extreme abrupt change threshold and the sawtooth amplitude threshold, and judging that the electron density profile is invalid if any one criterion is triggered. Preferably, the method for calculating the relative electron density change rate comprises the following steps: for each effective electron density profile, calculating the absolute value of electron density between adjacent height points: ; in the formula, Is the absolute difference of electron density; Is a height point Electron density of (a); Is a height point Electron density of (a); Based on the normalization of the electron density smaller values in the two adjacent points, the relative electron density change rate is obtained: ; in the formula, Is the rate of change of the relative electron density. Preferably, the genera