Thundercloud estimation device

Abstract

A thundercloud estimation device (100) that estimates the position of a thundercloud comprises: three or more detectors (D1 to D3) that detect gamma rays (51) generated from a thundercloud (50); a level measurement unit (13) that measures the gamma ray levels detected by the detectors (D1 to D3); and a calculation unit (14) that estimates, on the basis of the gamma ray levels detected by the detectors (D1-D3), the position of the thundercloud which is the source of the gamma rays.

Description

Thundercloud estimation device

[0001] The present disclosure relates to a thundercloud estimation device for estimating the position of a thundercloud.

[0002] As a method for predicting the occurrence of lightning strikes, Non-Patent Document 1 discloses a method of detecting electromagnetic waves generated by intra-cloud discharges with antennas installed at a plurality of points, and calibrating the lightning strike position based on the arrival directions and time differences of the simultaneously observed electromagnetic waves.

[0003] Non-Patent Document 2 also discloses a technique of predicting a region where lightning strikes are likely to occur by numerical calculation based on the information of the calibrated lightning strike points, and flying a drone in this region to induce lightning discharges.

[0004] Franklin Japan HP, https: / / www.franklinjapan.jp / network / jldn / NTT Space Environment Energy Research Institute HP, https: / / www.rd.ntt / se / media / article / 0045.html

[0005] However, in the technique disclosed in Non-Patent Document 1 described above, since it is premised that intra-cloud discharges are occurring, it is difficult to estimate the positions of newly generated thunderclouds and at the initial stage of thundercloud generation. Further, in the method disclosed in Non-Patent Document 1, there is a problem that the deviation in the accuracy of lightning strike position estimation is about several hundred meters to several kilometers, and the detection accuracy is low.

[0006] In the technique disclosed in Non-Patent Document 2, although it is possible to predict the point where a lightning strike will occur and fly a lightning-resistant drone to this predicted point to induce a lightning discharge, there is a problem that the estimation accuracy of the lightning strike occurrence point is low and it is difficult to fly the drone to an appropriate position.

[0007] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a thundercloud estimation device capable of accurately estimating the position of a thundercloud where a lightning strike will occur.

[0008] A thundercloud estimation device according to one aspect of the present disclosure is a thundercloud estimation device for estimating the location of a thundercloud, comprising: three or more detectors for detecting gamma rays emitted from a thundercloud; a level measuring unit for measuring the gamma ray level detected by the detectors; and a calculation unit for estimating the location of the thundercloud that is the source of the gamma rays based on the gamma ray level detected by each detector.

[0009] According to this disclosure, it will be possible to estimate the location of thunderclouds where lightning strikes are likely to occur with high accuracy.

[0010] Figure 1 is an explanatory diagram showing the schematic configuration of the thundercloud estimation device according to the first embodiment. Figure 2 is a block diagram showing the configuration of the thundercloud estimation device and its peripheral equipment according to the first embodiment. Figure 3 is an explanatory diagram showing the relationship between the installation positions P1 to P3 of each detector D1 to D3 and the ground position directly below the thundercloud. Figure 4 is a flowchart showing the processing procedure of the thundercloud estimation device according to the first embodiment. Figure 5 is a flowchart showing the processing procedure of the thundercloud estimation device according to a modified example of the first embodiment. Figure 6 is an explanatory diagram showing the schematic configuration of the thundercloud estimation device according to the second embodiment. Figure 7A is a plan view of the thundercloud estimation device according to the second embodiment. Figure 7B is a side view of the thundercloud estimation device according to the second embodiment. Figure 8 is a block diagram showing the configuration of the thundercloud estimation device and its peripheral equipment according to the second embodiment. Figure 9 is a flowchart showing the processing procedure of the thundercloud estimation device according to the second embodiment. Figure 10 is a block diagram showing the hardware configuration of this embodiment.

[0011] [Description of the First Embodiment] Figure 1 is an explanatory diagram showing the schematic configuration of the thundercloud estimation device 100 according to the first embodiment. The thundercloud estimation device 100 according to the first embodiment comprises a first detector D1, a second detector D2, a third detector D3, and a control device 1. The thundercloud estimation device 100 detects the position of the thundercloud 50 based on the gamma rays 51 detected by each of the detectors D1 to D3.

[0012] Figure 2 is a block diagram showing the configuration of the thundercloud estimation device 100 and its peripheral equipment according to the first embodiment. As shown in Figure 1, the thundercloud estimation device 100 is connected to the drone operator 5.

[0013] The control device 1 includes an extraction unit 11, a time difference measurement unit 12, a level measurement unit 13, a calculation unit 14, a display unit 15, and an output unit 16.

[0014] Each detector D1 to D3 is installed at any three locations on the ground surface. Each detector D1 to D3 detects gamma rays emitted from thunderclouds. Each detector D1 to D3 can be connected to the extraction unit 11 by wireless communication such as Wi-Fi or LTE, or by wired communication.

[0015] The extraction unit 11 extracts gamma ray waveforms from the detection data of each detector D1 to D3.

[0016] The time difference measurement unit 12 measures the time difference in the detection of gamma rays generated in the same thundercloud, based on the time at which gamma rays are detected by each detector D1 to D3. For example, the time difference measurement unit 12 uses the time at which gamma rays are detected by the detector that detected gamma rays earliest among the detectors D1 to D3 (let's call this detector D1) as a reference, and measures the elapsed time until the time at which the other detectors D2 and D3 detect gamma rays as a time difference. For example, measurement results such as "0" for the time difference of detector D1, "t1" for the time difference of detector D2, and "t2" for the time difference of detector D3 can be obtained.

[0017] The level measurement unit 13 measures the gamma-ray levels detected by each detector D1 to D3. For example, measurement results such as gamma-ray levels E1, E2, and E3 are obtained for each detector D1, D2, and D3.

[0018] The calculation unit 14 calculates the two-dimensional position on the ground surface directly beneath the thundercloud that is the source of gamma rays (referred to as the "ground position") based on at least one of the time difference measured by the time difference measurement unit 12 and the gamma-ray level measured by the level measurement unit 13. That is, the calculation unit 14 calculates the distance from each detector D1 to D3 to the ground position directly beneath the thundercloud based on the gamma-ray levels detected by each detector D1 to D3. As a method for calculating the ground position, a method using time difference or a method using gamma-ray level can be adopted, as shown below.

[0019] (1) Method using time difference In this method, after gamma rays are emitted from the thundercloud, the detector that detects the gamma rays fastest among the detectors D1 to D3 (let's call this detector D1) is identified. Based on the gamma ray level measured by detector D1, the distance r1 (see Figure 3) from detector D1 to the ground position directly below the thundercloud that is the source of the gamma rays is calculated. Furthermore, based on the calculated distance r1, the time required for the gamma rays to reach detector D1 from the point of origin (let's call this t0) is calculated. The distance r1 can be calculated based on the condition that the gamma ray level is inversely proportional to the square of the distance. Alternatively, the distance r1 may be calculated by referring to a correspondence table that shows the relationship between the gamma ray level and the distance r1, which has been set in advance. The time t0 can be calculated based on the gamma ray propagation speed and the distance r1. Alternatively, the time t0 may be calculated by referring to a correspondence table that shows the relationship between the distance r1 and the time t0, which has been set in advance.

[0020] As shown in Figure 3, the locations where detectors D1 to D3 are installed are denoted as points P1, P2, and P3, respectively. A circle R1 is defined with point P1 as the center and radius r1, as described above. A circle R2 is defined with point P2 as the center and radius r2, corresponding to the time obtained by adding the time difference t1 to time t0 (t0 + t1). Furthermore, a circle R3 is defined with point P3 as the center and radius r3, corresponding to the time obtained by adding the time difference t2 to time t0 (t0 + t2). The region Q1 where circles R1 to R3 intersect is estimated to be the ground position directly beneath the thundercloud.

[0021] (2) Method using gamma-ray levels In this method, gamma-ray levels E1 to E3 detected by each detector D1 to D3 are obtained. Each gamma-ray level E1 to E3 is inversely proportional to the square of the distance to the gamma-ray level at the source. Based on this condition, the distances r1 to r3 from each point P1 to P3 shown in Figure 3 to the ground position directly below the thundercloud are calculated. Furthermore, circles R1 to R3 are defined. The gamma-ray level at the source may be a predetermined value or a predicted value. Alternatively, a correspondence table showing the relationship between gamma-ray level and distance may be set in advance, and the distances r1 to r3 may be calculated by referring to this correspondence table and the circles R1 to R3 may be defined. As with (1) above, the region Q1 where each circle R1 to R3 intersects is estimated to be the ground position of the thundercloud.

[0022] Returning to Figure 2, the display unit 15 displays the ground position of the thundercloud estimated by the calculation unit 14, for example, on a display screen.

[0023] The output unit 16 outputs the ground position information estimated by the calculation unit 14 to the drone operator 5.

[0024] Next, the process of estimating the position of a thundercloud using the control device 1 according to the first embodiment will be explained with reference to the flowchart shown in Figure 4. Here, we will explain the case in which the method using the time difference shown in (1) above is adopted. First, in step S11 of Figure 4, the extraction unit 11 extracts the gamma ray waveform from the detection data detected by each detector D1 to D3.

[0025] In step S12, the time difference measurement unit 12 calculates the time difference in the arrival of gamma rays at each detector D1 to D3 based on the time at which gamma rays were detected at each detector D1 to D3. Specifically, the time at which gamma rays were detected at the detector that detected the gamma rays earliest among the detectors D1 to D3 (let's call this detector D1) is used as the reference time, and the elapsed time until the time of gamma ray detection at detector D2 is defined as the time difference t1, and the elapsed time until the time of gamma ray detection at detector D2 is defined as the time difference t2.

[0026] In step S13, the level measurement unit 13 measures the gamma ray level detected by each detector D1 to D3.

[0027] In step S14, the calculation unit 14 calculates the distance r1 from detector D1 (the detector that detected the gamma rays first) to the ground position directly below the thundercloud that is the source of the gamma rays, based on the gamma ray level detected by detector D1. Alternatively, it calculates the distance r1 by referring to a pre-set correspondence table. Furthermore, the calculation unit 14 calculates the time it takes for the gamma rays to reach detector D1 from the source of the gamma rays (this is called t0) based on the calculated distance r1.

[0028] In step S15, the calculation unit 14 calculates the ground position directly beneath the thundercloud based on the arrival time t0 and the time differences t1 and t2 described above. Specifically, as shown in Figure 3, the calculation unit 14 defines a circle R1 with a radius that corresponds to the distance r1 corresponding to time t0 from the position P1 of the detector D1. The calculation unit 14 defines a circle R2 with a radius that corresponds to the distance r2 corresponding to time (t0 + t1) from the position P2 of the detector D2. Furthermore, the calculation unit 14 defines a circle R3 with a radius that corresponds to the distance r3 corresponding to time (t0 + t2) from the position P3 of the detector D3. The calculation unit 14 estimates the ground position at point Q1 where the circles R1 to R3 intersect.

[0029] In step S16, the display unit 15 displays information about the ground position and informs the operator of the estimated ground position.

[0030] In step S17, the output unit 16 outputs ground position information to the drone operator 5. The drone operator 5 executes control to fly the lightning-resistant drone above the ground position, reach the thundercloud, and induce a lightning discharge. In this way, by flying the lightning-resistant drone to the location where the thundercloud is forming, it becomes possible to induce a lightning strike.

[0031] As described above, the thundercloud estimation device 100 according to this embodiment is a thundercloud estimation device 100 for estimating the location of a thundercloud, and comprises detectors D1 to D3 (three or more detectors) for detecting gamma rays 51 generated from the thundercloud 50, a level measuring unit 13 for measuring the gamma ray level detected by each detector D1 to D3, and a calculation unit 14 for estimating the location of the thundercloud that is the source of the gamma rays based on the gamma ray level detected by each detector D1 to D3.

[0032] In the thundercloud estimation device 100 according to this embodiment, the ground position directly below the thundercloud, which is the source of the gamma rays, is measured based on the time difference until the gamma rays generated by the thundercloud reach each detector D1 to D3. This makes it possible to detect the location of thunderclouds that are likely to cause lightning strikes with high accuracy.

[0033] It is known that thunderclouds emit gamma rays as a precursor to lightning strikes, several tens of seconds before the strike occurs. Therefore, by accurately predicting thunderclouds that are sources of gamma rays and flying lightning-resistant drones near these thunderclouds, it becomes possible to induce lightning discharges and reduce damage caused by lightning strikes.

[0034] In the first embodiment described above, an example was described in which three detectors D1 to D3 are installed to detect gamma rays, but the number of detectors may be four or more.

[0035] [Description of Modified Examples of the First Embodiment] Next, a modified example of the first embodiment will be described. In the modified example, the method using the gamma-ray level shown in (2) above is adopted to estimate the thundercloud location. Figure 5 is a flowchart showing the processing procedure of the thundercloud location estimation device according to the modified example. First, in step S31, the extraction unit 11 extracts the gamma-ray waveform from the detection data detected by the first to third detectors D1 to D3.

[0036] In step S32, the level measurement unit measures the gamma ray levels detected by each detector D1 to D3.

[0037] In step S33, the calculation unit 14 calculates the distance from each detector D1 to D3 to the ground position directly below the thundercloud that is the source of the gamma rays, based on the gamma-ray levels detected by each detector D1 to D3. As mentioned above, the gamma-ray level has the characteristic of being inversely proportional to the square of the distance, so the distance to the ground position can be calculated based on the gamma-ray level.

[0038] In step S34, the calculation unit 14 calculates the ground position based on the distance from each detector D1 to D3 to the ground position. Specifically, the distance from detector D1 to the ground position is r1, the distance from detector D2 to the ground position is r2, and the distance from detector D3 to the ground position is r3. As shown in Figure 3 above, circles R1, R2, and R3 can be defined centered on the positions P1, P2, and P3 of detectors D1, D2, and D3. The region Q1 where these circles R1 to R3 intersect is estimated to be the ground position directly below the thundercloud.

[0039] In step S35, the display unit 15 displays information about the ground position and informs the operator of the estimated ground position.

[0040] In step S36, the output unit 16 outputs ground position information to the drone operator 5. The drone operator 5 executes control to fly the lightning-resistant drone above the ground position, reach the thundercloud, and induce a lightning discharge. In this way, by flying the lightning-resistant drone to the location where the thundercloud is forming, it becomes possible to induce a lightning strike.

[0041] In this modified thundercloud estimation device 100, gamma-ray levels are detected by three detectors D1 to D3 installed on the ground, and the ground position directly beneath the thundercloud that is the source of gamma rays is measured based on each gamma-ray level. This makes it possible to detect the location of thunderclouds that are likely to cause lightning strikes with high accuracy. By flying a lightning-resistant drone near the detected location, lightning discharges can be induced, making it possible to reduce damage caused by lightning strikes.

[0042] [Description of the Second Embodiment] Next, a second embodiment will be described. Figures 6, 7A, and 7B are explanatory diagrams showing the thundercloud estimation device 101 according to the second embodiment, with Figure 6 showing a schematic configuration, Figure 7A showing a plan view, and Figure 7B showing a side view.

[0043] As shown in each figure, the thundercloud estimation device 101 according to the second embodiment includes four detectors, namely, a first detector D1, a second detector D2, a third detector D3, and a fourth detector D4. The thundercloud estimation device 101 detects gamma rays 51 (see FIG. 6) generated by the thundercloud 50 using each detector D1 to D4, and estimates the position of the thundercloud 50 based on the detected gamma rays. Each of the detectors D1 to D4 is installed with its direction shifted by 90 degrees from each other in the horizontal plane, for example, facing the east, south, west, and north directions on the ground surface respectively.

[0044] Each of the detectors D1 to D4 has an elevation angle set at 45 degrees. As shown in FIG. 6, each of the detectors D1 to D4 detects the gamma rays 51 generated by the thundercloud 50. Each of the detectors D1 to D4 detects the incident angle of the gamma rays. Note that the elevation angle is not limited to 45 degrees and may be an angle other than 45 degrees. Also, the elevation angles of each of the detectors D1 to D4 may be variable. The number of detectors may be four or more.

[0045] FIG. 8 is a block diagram showing the configuration of the thundercloud estimation device 101 according to the second embodiment and its peripheral devices. As shown in FIG. 8, the thundercloud estimation device 101 includes four detectors D1 to D4 and a control device 2. The control device 2 is connected to a drone operator 5.

[0046] The control device 2 includes an extraction unit 21, an incident angle measurement unit 22, a level measurement unit 23, a calculation unit 24, a display unit 25, and an output unit 26.

[0047] The extraction unit 21 extracts the waveform of the gamma rays from the detection data in each of the detectors D1 to D4.

[0048] The incident angle measurement unit 22 measures the incident angle of the gamma rays incident on the detection surface of each of the detectors D1 to D4 based on the gamma rays detected by each of the detectors D1 to D4.

[0049] The level measurement unit 23 measures the gamma ray level detected by each of the detectors D1 to D4. For example, for each of the detectors D1 to D4, measurement results such as gamma ray levels E1 to E4 are obtained respectively.

[0050] The calculation unit 24 calculates the three-dimensional position of the thundercloud that is the source of the gamma rays based on the incident angle of the gamma rays measured by the incident angle measurement unit 22 and the gamma ray level measured by the level measurement unit 23. Specifically, the calculation unit 24 acquires the gamma ray level obtained from the detector with the highest gamma ray level among the four detectors D1 to D4 (let's call this detector D1). The calculation unit 24 also acquires the incident angle of the gamma rays measured by the incident angle measurement unit 22.

[0051] The calculation unit 24 calculates the distance from detector D1 to the thundercloud, which is the source of the gamma rays, based on the gamma-ray level and the angle of incidence. As mentioned above, the gamma-ray level is inversely proportional to the square of the distance from the gamma-ray source, so the distance from detector D1 to the thundercloud is measured based on this characteristic. The gamma-ray level at the source may be a predetermined value or a predicted value. That is, the calculation unit 24 identifies the detector that detected the highest level of gamma rays among the detectors D1 to D4 (for example, detector D1), and calculates the position of the thundercloud based on the gamma-ray level detected by the identified detector D1 and the angle of incidence of the gamma rays.

[0052] The display unit 25 displays the thundercloud location information estimated by the calculation unit 24, for example, on a display screen.

[0053] The output unit 26 outputs the thundercloud location information estimated by the calculation unit 24 to the drone operator 5.

[0054] Next, the process of detecting the location of a thundercloud using the control device 2 according to the second embodiment will be explained with reference to the flowchart shown in Figure 9. First, in step S51, the extraction unit 21 extracts the gamma ray waveform from the detection data detected by the first to fourth detectors D1 to D4.

[0055] In step S52, the level measurement unit 23 measures the gamma ray levels detected by each detector D1 to D4. The measurement results are output to the calculation unit 24.

[0056] In step S53, the incident angle measuring unit 22 measures the incidence of gamma rays. The measurement result is output to the calculation unit 24.

[0057] In step S54, the calculation unit 14 identifies the detector (referred to as detector D1) that measured the highest gamma-ray level among the detectors D1 to D4, and calculates the position of the thundercloud, which is the source of the gamma rays, based on the gamma-ray level and the incident angle of the gamma rays detected by detector D1. That is, the distance from detector D1 to the thundercloud can be calculated based on the gamma-ray level, and the direction of the thundercloud relative to the detection surface of detector D1 can be calculated based on the incident angle of the gamma rays. From these calculation results, the position of the thundercloud (three-dimensional coordinates) can be calculated.

[0058] In step S55, the display unit 25 displays information about the location of the thundercloud and informs the operator of the estimated location of the thundercloud.

[0059] In step S56, the output unit 26 outputs information about the thundercloud location to the drone operator 5. The drone operator 5 executes control to fly the lightning-resistant drone to or near the thundercloud location, to reach the thundercloud, and induce a lightning discharge. In this way, by flying the lightning-resistant drone to the location where the thundercloud is generated, it becomes possible to induce a lightning strike.

[0060] As described above, the thundercloud estimation device 101 according to the second embodiment measures the gamma-ray level and the angle of incidence of gamma rays using four detectors D1 to D4 installed on the ground, and determines the location of the thundercloud that is the source of gamma rays based on this information. Therefore, it becomes possible to detect the location of thunderclouds that are likely to cause lightning strikes with high accuracy. By flying a lightning-resistant drone near the detected location, it is possible to induce lightning discharges and reduce damage caused by lightning strikes.

[0061] In the second embodiment described above, an example was explained using four detectors D1 to D4 that are oriented 90 degrees apart from each other. However, the orientation of each detector is not limited to 90-degree intervals. Furthermore, five or more detectors may be installed.

[0062] As shown in Figure 10, the control devices 1 and 2 of this embodiment described above can be general-purpose computer systems that include, for example, a CPU (Central Processing Unit, processor) 901, memory 902, storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), communication device 904, input device 905, and output device 906. The memory 902 and storage 903 are storage devices. In this computer system, the CPU 901 executes a predetermined program loaded onto the memory 902, thereby realizing the functions of the control devices 1 and 2.

[0063] The control devices 1 and 2 may be implemented on a single computer, or on multiple computers. Furthermore, the control devices 1 and 2 may be virtual machines implemented on a computer.

[0064] The programs for control devices 1 and 2 can be stored on computer-readable recording media such as HDDs, SSDs, USB (Universal Serial Bus) memory, CDs (Compact Discs), and DVDs (Digital Versatile Discs), or they can be distributed via a network. Computer-readable recording media are, for example, non-transitory recording media.

[0065] This disclosure is not limited to the embodiments described above, and numerous modifications are possible within the scope of its essence.

[0066] 1, 2 Control device 5 Drone operator 11, 21 Extraction unit 12 Time difference measurement unit 13, 23 Level measurement unit 14, 24 Calculation unit 15, 25 Display unit 16, 26 Output unit 22 Incidence angle measurement unit 50 Thundercloud 51 Gamma rays 100, 101 Thundercloud estimation device D1 First detector D2 Second detector D3 Third detector D4 Fourth detector

Claims

1. A thundercloud estimation device for estimating the location of a thundercloud, comprising: three or more detectors for detecting gamma rays emitted from a thundercloud; a level measuring unit for measuring the gamma ray levels detected by the detectors; and a calculation unit for estimating the location of the thundercloud that is the source of the gamma rays based on the gamma ray levels detected by each detector.

2. The thundercloud estimation device according to claim 1, further comprising a time difference measuring unit that measures the time difference in the detection of gamma rays at each detector based on the time at which gamma rays are detected at each detector, wherein the calculation unit calculates the ground position directly below the thundercloud based on the gamma ray level and the time difference.

3. The thundercloud estimation device according to claim 1, wherein the calculation unit calculates the distance from each detector to the ground position directly below the thundercloud based on the gamma-ray level detected by each detector, and estimates the ground position directly below the thundercloud based on the distance to the ground position calculated by each detector.

4. A thundercloud estimation device according to claim 1, further comprising four or more detectors, an incidence angle measuring unit for measuring the incidence angle of gamma rays incident on each detector, wherein the calculation unit identifies the detector that has detected the highest level of gamma rays among the detectors, and estimates the location of the thundercloud based on the gamma ray level and the incidence angle of gamma rays detected by the identified detector.

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