Identification and matching methods of two lightning location systems for the same ground lightning return stroke event

Abstract

The present invention provides a method for identifying and matching the same ground lightning return stroke event by two lightning location systems. Belonging to the field of meteorology, the method first collects the monitoring data of the ADTD two-dimensional and VLF / LF three-dimensional lightning location systems, and performs quality control. Then, a time-space matching window is selected, and the matching rate of the two systems for the same return stroke event is calculated. Next, a relative positioning deviation calculation method is established to count the relative time deviation and positioning distance difference of the two systems for the same return stroke event. The present invention finds the time-space matching windows of the ADTD two-dimensional and VLF / LF three-dimensional lightning location systems for the same return stroke event, and analyzes the time-space positioning deviation of the positioning results of the same return stroke event by different systems. Without conducting artificial lightning induction tests or collecting lightning disaster information, it is possible to evaluate the detection performance and accuracy of the lightning location system, which provides an important technical method for improving the reliability of the business application of ground-based lightning monitoring data and realizing the supplementation and correction of different lightning monitoring data.

Description

Technical Field

[0001] The invention belongs to the field of meteorology, and more specifically relates to a method for identifying and matching two lightning location systems for the same ground lightning return stroke event. Background Art

[0002] In recent years, with the continuous development of ground-based lightning location monitoring systems, it has provided important technical support for the analysis of cloud-to-ground lightning activity changes, lightning warning and lightning disaster prevention. Since the monitoring data of the lightning location system is obtained through instrument calculation and inversion, it is not the actual ground-to-ground lightning return information, and the real ground-to-ground lightning return latitude and longitude, lightning current intensity and other information are unknown. At present, there are few studies on the detection performance of lightning location systems. In order to evaluate the detection efficiency and accuracy of lightning location systems, artificial lightning is usually used to obtain the actual location of lightning strikes and current waveforms in lightning channels, or the actual location of lightning strikes is obtained through lightning disaster surveys, and then compared with the monitoring inversion data of the lightning location system, so as to obtain the time and distance errors between the system and the actual ground-to-ground lightning return, thereby evaluating the detection performance of the lightning location system.

[0003] The sample size of actual lightning strike point information obtained through artificial lightning induction and lightning disaster investigation data is relatively small, making it difficult to evaluate the accuracy and efficiency of lightning location inversion data.

[0004] The economic investment required to obtain actual lightning strike point information by conducting artificial lightning induction tests is high, and it has strict requirements on the surrounding site environmental conditions. It must be carried out in a standardized artificial lightning induction observation field test base. Lightning induction tests also pose risks to the life safety of operators. Summary of the invention

[0005] The present invention adopts ADTD two-dimensional and VLF / LF three-dimensional lightning location system observation data to innovatively study the identification and matching methods of two different lightning location systems for the same return stroke event. On this basis, the relative spatiotemporal positioning deviations of the positioning results of the same return stroke event by different systems are analyzed. Without conducting artificial lightning induction tests or collecting lightning disaster information, the detection performance and accuracy of the lightning location system can be evaluated, which provides an important technical method for improving the reliability of the business application of ground-based lightning monitoring data and realizing the supplementation and correction of different lightning monitoring data. It provides new technical methods and means for carrying out the inspection and evaluation of the detection performance of the lightning location monitoring system, filling the gap in this field.

[0006] In order to achieve the above object, the present invention is implemented by adopting the following technical scheme: the identification and matching method comprises:

[0007] Data collection, ADTD two-dimensional lightning location data, VLF / LF three-dimensional lightning location data;

[0008] Select the time and space matching windows of the two systems for the same ground flash backstroke event;

[0009] Calculate the matching rate of the two systems for the same return strike event;

[0010] Construct a calculation method for the relative positioning deviation of the two systems for the same return strike event;

[0011] Verify the identification and matching method.

[0012] In one embodiment, the data collection collects two types of ground lightning return stroke monitoring data, namely, ADTD two-dimensional lightning location system and VLF / LF three-dimensional lightning location system, and performs quality control.

[0013] In one solution, the space-time matching window is as follows: the space window range is set to 10km, the time windows are selected to be 1ms and 50ms, and the return records of different systems are matched in the two space-time windows of 10km, 1ms and 10km, 50ms respectively.

[0014] In one embodiment, the matching rate of the same response event is calculated by calculating the probability that at least one response from the two-dimensional system in the space-time matching window successfully matches the response from the three-dimensional system, i.e., the matching rate; or the probability that at least one response from the three-dimensional system in the space-time matching window successfully matches the response from the two-dimensional system;

[0015] In the matching process, if one record matches multiple records, it is called redundancy. The record with the smallest time difference is selected to ensure one-to-one correspondence between the matching numbers.

[0016] In one solution, the relative positioning deviation method counts the matched responses of the two systems in a 10km, 1ms space-time window, and finds that the relative time deviation of the matched responses of the two systems is mainly concentrated within 0.05ms, and the relative positioning distance difference is concentrated within 1km.

[0017] In one solution, the identification and matching method is verified by analyzing the difference in current amplitudes of the matched return strokes of the two systems under a 10 km, 1 ms window.

[0018] In one embodiment, the matching rate, the best matching time and space window for the same return stroke event of two different lightning location systems, ADTD and VLF / LF, is 10km and 1ms, and the matching rate for the same return stroke obtained under this window tends to be stable.

[0019] In one solution, the data quality control includes: eliminating return stroke records obtained by the two-station positioning method; eliminating positive return stroke data with lightning current amplitudes between 0 and 10 kA; and eliminating positive and negative return stroke records with absolute values ​​greater than 200 kA.

[0020] Beneficial effects of the present invention:

[0021] 1. The ground lightning return stroke information monitored by the lightning location system is obtained by instrument inversion calculation. To understand the detection efficiency and accuracy performance of the lightning location system, it is usually necessary to conduct artificial lightning induction tests to obtain the actual lightning strike point information, and then compare it with the information inverted by the synchronous observation of the lightning location system, and analyze the time and space errors between the lightning location system monitoring and the actual lightning strike point of artificial lightning induction, so as to master the detection efficiency and accuracy of the lightning location system. However, the cost investment required for conducting artificial lightning induction tests is high, and it must be organized and carried out in specific standardized sites. At the same time, lightning induction tests pose a threat to the safety of personnel lives.

[0022] 2. In view of the fact that there are few studies on the detection error analysis and performance effect evaluation of lightning location systems at this stage, the present invention innovatively invents an identification and matching algorithm for the same return stroke event by two different lightning location systems when the actual lightning strike point information is difficult to obtain. On this basis, the relative spatiotemporal positioning deviations of the positioning results of the same return stroke event by different systems are analyzed, and it is found that the relative positioning time difference of the two systems for the same return stroke is mainly concentrated within 0.05ms, and the distance deviation is concentrated within 1km. Without conducting artificial lightning induction tests or collecting lightning disaster information, it is possible to achieve an objective evaluation of the system's detection performance, and at the same time achieve correction and supplementation between different lightning location systems, providing an important technical method for improving the reliability of business applications of ground-based lightning monitoring data and achieving supplementation and correction of different lightning monitoring data. It provides new technical methods and means for conducting detection performance inspection and evaluation of lightning location monitoring systems, filling the gap in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a flow chart of the method of the present invention;

[0024] Figure 2 The matching conditions of the two systems of the present invention for the same return strike event in different time and space windows;

[0025] Figure 3 The positive and negative return current amplitudes after matching in the present invention are fitted (a. positive return; b. negative return;

[0026] Figure 4 Matching the positive and negative return stroke current amplitude distributions for the present invention;

[0027] Figure 5It is the cumulative probability distribution of the positive and negative return stroke current amplitudes matched by the present invention. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in the present invention. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0029] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0030] The identification and matching methods of the two lightning location systems for the same ground lightning return stroke event include:

[0031] S1. Data collection: ADTD two-dimensional lightning location data, VLF / LF three-dimensional lightning location data.

[0032] The two types of ground lightning return stroke monitoring data from the ADTD two-dimensional lightning location system and the VLF / LF three-dimensional lightning location system in Yunnan Province from 2017 to 2020 were used and quality control was performed. First, the return stroke records obtained by the two-station positioning method were eliminated; second, the positive return stroke data with a lightning current amplitude of 0-10kA were eliminated to avoid interference from small-amplitude currents of cloud flashes; third, the positive and negative return stroke records with absolute values ​​greater than 200kA were eliminated.

[0033] S2. Select the time-space matching windows of the two systems for the same ground flash backstroke event.

[0034] Spatiotemporal matching method for the same ground-to-ground flash backstroke event using two different lightning location systems. In order to ensure that the detection records matched by the two systems belong to the same backstroke event and to allow as many backstrokes as possible to participate in the matching analysis to reduce the omission of backstrokes, this study selected a spatial window range of 10km to ensure that the backstrokes involved in the matching belong to the same ground-to-ground flash. Taking into account the shorter and longer backstroke time intervals, the time windows of 1ms and 50ms were selected, and the backstroke records of different systems were matched in the two spatiotemporal windows of 10km, 1ms and 10km, 50ms, respectively.

[0035] Considering the existence of bipolar ground lightning, positive and negative return strokes are not distinguished in the matching process. In the two time and space windows of 10km, 1ms and 10km, 50ms, for each two-dimensional return stroke detection record, the three-dimensional return stroke records of the same year are searched for records with a positioning distance within 10km and a time difference of 1ms and 50ms respectively.

[0036] S3. Calculate the matching rate of the two systems for the same return attack event.

[0037] Count the number of identical hits between the two systems corresponding to the two time-space windows. That is, calculate the probability (i.e., matching rate) that at least one hit of the two-dimensional system (three-dimensional system) in the window successfully matches the hit of the three-dimensional system (two-dimensional system). During the matching process, if one record of one system matches multiple records (i.e., redundancy), select the record with the smallest time difference to ensure one-to-one matching.

[0038] Calculate the proportion of the matched hitbacks in the total hitbacks of the ADTD 2D system and the VLF / LF 3D system. Figure 2 As shown in the figure, under the 10km, 1ms time-space window, the number of hits that can be matched in the four-year combined detection records of the two systems accounts for 72.1% of the total hits of the two-dimensional system and 25.3% of the total hits of the three-dimensional system. The year-by-year hit matching rate of the two-dimensional system is between 63.4% and 79.2%, and the year-by-year hit matching rate of the three-dimensional system is between 20.6% and 32.0%. When the time window is expanded to 50ms, the year-by-year matching rate of the two-dimensional system is between 66.7% and 80.7%, and the matching rate of the four-year combined hits reaches 74.2%. The four-year total hit matching rate of the three-dimensional system is 26.1%, and the year-by-year matching rate is between 21.4% and 32.5%. The matching rate of the three-dimensional system is lower because the number of hits of the three-dimensional system before matching is 2.8 times that of the two-dimensional system, and the base number is larger. It can be seen that even if the time interval is expanded to 50ms, the increase in matching rate compared with the 1ms time window is not obvious, thus finding that the best matching spatiotemporal windows for the same return stroke event for the two different lightning location systems ADTD and VLF / LF are 10km and 1ms, and the matching rate for the same return stroke obtained under this window has tended to be stable.

[0039] S4. Construct a relative positioning deviation method for the two systems for the same return strike event.

[0040] The relative positioning deviation of the two systems for the same return stroke was studied. The same return stroke records that have been matched by the two systems were counted, and the matched return strokes in the 10km and 1ms time and space windows were analyzed, as shown in Table 1. From a spatial perspective, the relative distance difference between the two systems matching the same return stroke event within 0.1km and 0.5km accounted for 1.0% and 20.4% respectively, except for the points with the same longitude and latitude (the longitude and latitude accuracy of the same matching point is defined as 10 in this study). -4), the minimum distance difference of matching responses is 1.1m, and the relative distance difference is mainly concentrated within 1km, accounting for 54.0%, 91.9% of the matching response distance difference is within 3km, and the distance difference greater than 3km accounts for 8.1%. In terms of time difference, the number of matching responses with the same time (this study defines the time to be accurate to 0.001ms) accounts for 3.6%, 71.8% of the matching response time deviation is within 0.005ms, and the response with a time deviation of ≤0.05ms accounts for 96.0%, and the matching response with a deviation of >0.1ms accounts for a small proportion (1.5%). It is concluded that the relative time deviation of the matching responses of the two systems is mainly concentrated within 0.05ms, and the relative positioning distance difference is concentrated within 1km.

[0041] Table 1 Relative positioning temporal and spatial deviations of the same return hit matching results of the two systems under 10km and 1ms windows

[0042]

[0043] Analyze the spatial distribution of the matching time and space deviations of the two systems for the same return stroke in different regions. Take the matched return stroke records of the two systems under the 10km and 1ms time and space windows as an example.

[0044] Matching responses with a relative distance difference of ≤0.5km are mainly concentrated in central and southwestern Yunnan, but are less distributed in northwestern and western Yunnan. Matching responses with a distance difference of >3km have increased significantly in northwestern Yunnan and other places. In terms of time difference, except for Diqing in northwestern Yunnan and northern Nujiang, the relative positioning time difference of the two systems for the same response in most parts of the province is within 0.05ms, and matching responses with a time difference of >0.1ms account for a relatively small proportion.

[0045] S5. Verify the identification and matching method.

[0046] Method verification. The current amplitude difference of the matched return strokes of the two systems under the 10km and 1ms window was analyzed. As shown in Table 2, from the perspective of return stroke polarity, the proportion of matched return strokes with one-to-one polarity is 98.3%, of which positive return stroke accounts for 4.6% and negative return stroke accounts for 93.7%. Since bipolar ground flashes are considered in the matching process, there are a small number of matched return stroke records with different polarities, which account for a small proportion (1.7%). The fitting effect of the positive and negative matching return stroke current amplitudes corresponding to the polarity is good. The correlation coefficient of the positive return stroke current amplitude of the two systems is 0.924, and the correlation coefficient of the negative return stroke is 0.772 ( Figure 3 ).

[0047] Table 2 Comparison of the amplitude difference of matched return strokes of the two systems

[0048]

[0049] From the distribution of current amplitude of matched return stroke ( Figure 4 ), there is no obvious difference in the distribution of positive and negative return stroke current amplitudes of the two systems, and the correspondence between the median, mean, 95% quantile and 5% quantile is good. The relative errors of the mean and median of the positive return stroke current of the two systems are only 0.5% and 3.1%, and the relative errors of the mean and median of the negative return stroke current are 2.6% and 5.0%. In addition, the amplitude ratios of the positive and negative return stroke sample currents in the three-dimensional and two-dimensional system matching are 1.03 and 1.07, respectively, indicating that the current intensity of the matched return stroke has a high consistency. From the cumulative probability distribution of lightning current amplitude ( Figure 5 ), for the same backstroke, the positive and negative backstroke current amplitude cumulative probability curves inverted by the two systems are almost the same. The current amplitude distribution trend of the same backstroke matched by the two systems is consistent, and the corresponding effect is good.

[0050] The above results verify that the inversion results of the two systems for the same return stroke current intensity are highly consistent, and also verify that the space-time window threshold selection and matching method of the present invention for the same return stroke event around the two systems is objective and reliable.

[0051] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM).

[0052] It should be understood that the detailed description of the technical solutions of the present invention by means of the preferred embodiments is illustrative rather than restrictive. A person skilled in the art may modify the technical solutions described in the embodiments, or replace some of the technical features by equivalents, based on reading the specification of the present invention; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying and matching two lightning location systems for the same ground lightning return stroke event, characterized in that: The identification and matching method comprises: Data collection, ADTD two-dimensional lightning location data, VLF / LF three-dimensional lightning location data; Select the time and space matching windows of the two systems for the same ground flash backstroke event; Calculate the matching rate of the two systems for the same return strike event; Construct a calculation method for the relative positioning deviation of the two systems for the same return strike event; Verify the identification and matching method; The data collection includes collecting two types of ground lightning return stroke monitoring data of the ADTD two-dimensional lightning location system and the VLF / LF three-dimensional lightning location system, and performing quality control; The time-space matching window is as follows: the space window range is set to 10km, the time windows are selected to be 1ms and 50ms, and the return records of different systems are matched in the two time-space windows of 10km, 1ms and 10km, 50ms respectively; The matching rate of the same response event is calculated as follows: the matching rate of at least one response from the two-dimensional system in the space-time matching window successfully matching with the response from the three-dimensional system; or the probability of at least one response from the three-dimensional system in the space-time matching window successfully matching with the response from the two-dimensional system; In the matching process, if one record matches multiple records, it is called redundancy. The record with the smallest time difference is selected to ensure that the number of matches corresponds one to one. The relative positioning deviation calculation method is to count the matched return shots of the two systems in the 10km, 1ms time-space window, and it is concluded that the relative time deviation of the matched return shots of the two systems is mainly concentrated within 0.05ms, and the relative positioning distance difference is concentrated within 1km; The identification and matching method is verified, and the current amplitude difference analysis is performed on the matched return strokes of the two systems under the 10km and 1ms window; The matching rate mentioned above, the best matching time and space window for the same return stroke event of the two different lightning location systems ADTD and VLF / LF is 10km and 1ms, and the matching rate for the same return stroke obtained under this window tends to be stable.

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