JP2519657B2 - Lightning detection method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of lightning, and more particularly to prediction of lightning strikes to ground facilities and lightning protection, or effective use of electric energy of lightning.

[0002]

2. Description of the Related Art Conventionally, as a method for predicting lightning strikes, a method of detecting a thundercloud at an early stage by a weather radar has been known and has been put to practical use at airports and the like. Other known lightning detection methods include an electric field sensing type thundercloud detection system that measures and predicts an electric field between a cloud and the ground, and a lightning detection method using an electromagnetic wave receiver.

[0003]

However, among the above-mentioned methods, the method using the weather radar can only provide information such as the cross-sectional structure of clouds, but cannot provide information about the distribution of charges. It is up to the person observing the radar image to decide whether or not. In the electric field sensing type thundercloud detection system, in the case of a normal thundercloud in which positive and negative charges are vertically distributed, it is essentially a scalar measurement just by observing the electric field on the ground. Since it is not a vector measurement to measure, it is difficult to accurately grasp the potential distribution in the upper cloud. Furthermore, since this method can only be measured directly below the thundercloud, it is extremely difficult to detect the incoming thundercloud in advance. Although it is possible by arranging sensors etc., there is currently no effective countermeasure against thunderclouds coming from the sea. Then, the electromagnetic wave receiver method is intended to capture electromagnetic waves generated during discharge in clouds and between clouds using a normal antenna and receiver. This method has an advantage that a system can be constructed by combining inexpensive commercially available parts, etc., but if an attempt is made to instantaneously detect the direction of an electromagnetic wave, a large number of antennas and receivers are arranged and their received signals are The direction cannot be calculated without the synthesis process, and the system scale tends to increase. further,
The problem is that it is essentially impossible to grasp the vector of the air discharge. In this way, in the conventional lightning detection method,
Only electric fields and electromagnetic waves associated with air discharge were used for detection. Since the electric field and electromagnetic waves are captured as a scalar quantity, it was possible to confirm the azimuth by installing an electric field sensor in a wide area or by wrapping the antenna around the entire circumference, but it was not possible to grasp the direction of current flow. It was
Therefore, even if there is data on cloud structure from meteorological radar, it was not possible to link them directly and use them for detection of lightning. The present invention has been made to solve the above problems, and an object of the present invention is to provide a lightning detection method and apparatus capable of detecting the position and direction of a lightning strike position and aerial discharge.

[0004]

In order to solve the above-mentioned problems, the lightning detection method according to the present invention comprises a first step of detecting cloud data relating to the internal structure of clouds by a weather detection means and a preceding phenomenon of lightning strike. A second step of detecting a magnetic field generated by a leak current or an aerial discharge phenomenon as magnetic field vector data by the magnetic detection means, a third step of inversely estimating the direction of the electric current of the lightning from the magnetic field vector data, and the cloud. The fourth step of calculating the charge distribution in the cloud of interest from the data and the inversely estimated current direction, and the ground current is obtained by measuring the ground potential difference or magnetism, and the change of the ground potential with respect to the thundercloud. From the fifth step of calculating the distribution, the cloud charge distribution, and the ground potential change distribution, the ground position where the probability of a lightning strike is maximum and the discharge in the cloud in that case 6 to determine the direction of the location and current
And steps. In addition, the lightning detection device according to the present invention detects the cloud data regarding the internal structure of the cloud, the weather detection means, and the magnetic field generated by the leakage current or the aerial discharge phenomenon, which is a preceding phenomenon of lightning strike, as magnetic field vector data. From the magnetic detection means, the lightning current inverse estimation means for inversely estimating the direction of the electric current of the thunderstorm from the magnetic field vector data, and the cloud data and the inversely estimated current direction, the charge distribution in the cloud of interest. A cloud charge distribution calculating means for calculating the ground potential change distribution calculating means for calculating a ground current by measuring a ground potential difference or magnetism, and calculating a ground potential change distribution for a thundercloud, and the cloud charge distribution The ground potential change distribution and the lightning strike prediction means for determining the discharge position and current direction in the cloud in that case are configured from the ground potential change distribution.

[0005]

According to the present invention having the above structure, the SQU
A magnetic detection means such as an ID sensor is provided, and a magnetic field generated by a leak current or cloud discharge, which is a preceding phenomenon of a lightning strike, can be detected as vector amount data. From this vector data, the direction of the current of lightning is reversed. The charge distribution in the cloud can be calculated by estimating and combining with the observation data such as the cloud structure, for example, the cross-sectional shape, the wind speed, etc. by the weather detection means such as the weather radar. To the above information, add the ground potential change distribution for the thundercloud, which is calculated from the ground current obtained by measuring the ground potential difference or magnetism, and make a comprehensive judgment from the above cloud charge distribution and ground potential change distribution. This makes it possible to predict the ground position where the lightning strike probability is maximum, the position of the cloud discharge destination at that time, and the direction of the discharge current.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 shows a procedure of a lightning detection method according to the first embodiment of the present invention. First, as a first step, the weather radars 1 ₁ to 1 _n are used to observe a cloud C, which is thought to be a thundercloud, and the motion data of the cloud C and the structure data inside the cloud (for example, the cross-sectional shape of the cloud C) are clouds. Detect data.

[0007] Next, as a second step, a plurality of SQUID sensors 2 ₁ to 2 _n is a magnetic detecting means, the magnetic field generated by phenomena such as leakage current and atmospheric discharge D is prior phenomenon of lightning as a vector quantity measure. In this case, 2 _{1 to} 2 _n may be of a magnetic sensor, or any other type as long as it is a highly sensitive magnetic sensor. Next, the third
As a step, the electric current of the thunderbolt in the thundercloud C is estimated in reverse from the magnetic field captured as a vector quantity by the above measurement.

[0008] and then, as a third step, from the cloud data and reverse the estimated current value, the charge e ⁺ and e of the positive and negative in the thundercloud C ^- to calculate the distribution. Next, as a fourth step, the ground current (current flowing through the ground surface G) I _G is measured by a sensor or the like that measures a potential difference or magnetism, and the distribution of changes in the ground potential with respect to the monitored thundercloud C is measured. To calculate.

Next, as a fifth step, the results of each of the above-mentioned processes are comprehensively predicted, and the position of the ground G at which the probability of a lightning strike is most likely to occur and the discharge of the thundercloud C at that time are calculated. Calculate the expected position and the expected discharge current direction. Finally, as a sixth step, the above-described lightning strike prediction calculation result is provided to other lightning protection systems and the like, and is also provided as weather information such as "lightning protection warning".

Next, the configuration of the second embodiment of the present invention is shown in FIG. As shown in the figure, this lightning strike prediction system 100, which is a lightning detection device, includes a plurality of meteorological radars 1 ₁ to 1 _n and SQUID sensors 2 arranged in a wide area on the ground G.
_{1 to} 2 _n, ground current measuring sensor 3 _{1 to} 3 _n , and analysis system 2
0, an image display device 11 and a print output device 12.

The above-mentioned analysis system 20 includes a cloud motion / cloud structure analysis device 5, a magnetic field vector analysis device 6, a lightning current inverse estimation device 7, a thundercloud charge distribution calculation device 8, and a ground potential change distribution calculation device. 9 and a lightning strike position / direction prediction processing device 10. The analysis system 20 may be a combination of individual devices, but in actuality, the whole can be constituted by one mainframe computer system, workstation, or personal computer.

Next, the operation of this system will be described. First, the weather radars 1 ₁ to 1 _n observe a cloud C which is considered to be a thundercloud, collect motion data of the cloud C and structure data inside the cloud, and output the data to the cloud motion / cloud structure analysis device 5. The cloud movement / cloud structure analysis device 5 analyzes the collected data and detects cloud data. In this case, the weather radar 1 ₁
.About.1 _n and the cloud movement / cloud structure analysis device 5 constitute meteorological detection means.

Next, the cloud movement / cloud structure analysis device 5 outputs this cloud data to the lightning strike position / direction prediction processing device 10. In this case, in order to further improve the accuracy of the motion property data of the cloud C, a measuring device for wind speed, wind direction, etc., a data processing device, etc. may be incorporated in the system 100.

Simultaneously with the cloud observation, a plurality of SQUID sensors 2 ₁ to 2 _n are used as a vector quantity to generate a magnetic field generated by a phenomenon such as a leak current or an aerial discharge D, which is a preceding phenomenon of a lightning strike, with respect to the target cloud C. The measured data is output to the magnetic field vector analysis device 6. In this case, the plurality of SQUID sensors 2 ₁ to 2 _n and the magnetic field vector analysis device 6 constitute magnetic detection means.

[0015] At this time, above the cloud observed, and co-parallel to the magnetic field measurement, the ground potential measuring sensor 3 ₁ to 3 _n, the ground surface G directly below the above-mentioned target cloud C, the measurement of such earth potential or magnetic And the obtained data is used as a ground potential change distribution calculation device 9
Output to.

Next, the above SQUID sensors 2 ₁ to 2 _n
The direction of the lightning current in the thundercloud C is estimated in reverse by the lightning current reverse estimation device 7 based on the magnetic field data measured as the vector quantity by the magnetic field vector analysis device 6.

FIG. 3 shows the method of inverse estimation of the current direction.
Will be described with reference to. First, in order to formulate the problem, we consider a method of mathematically expressing the current of the Raiden, which is the estimation target. Since the object to be obtained now is to estimate the central position of the electric current of the lightning, we will treat it as a current dipole. The current dipole is completely described by 6 parameters. That is, its position is described by x-coordinates, y-coordinates, and z-coordinates, its direction is described by an angle θ formed by the z-axis, and an angle φ formed by the x-axis, and its current value is expressed by an ampere value I.
Described by.

Regarding the magnetic field generated by the current dipole, the following equation, which is the Biot-Savart law, B (r) = (μo / 4π)  {In × (rs)} / │r −s | ³ (1)

In the above equation (1), s is the position of the current dipole, n is the unit vector representing the direction of the current dipole,
r represents a measurement position, and μo / 4π represents a proportional constant.

From the above consideration, the problem of inversely estimating the current direction of the lightning current is that the above six parameters of the current dipole are estimated from the measurement results of the N magnetic sensors with the above equation (1) as a constraint condition. (See Figure 3).

In this case, since the number of unknowns is 6 from the equation form, if there are 6 or more measurement points,
In principle, this problem can be solved. However, in practice, it is very difficult to solve this analytically, so it is advisable to use an optimization algorithm of mathematical programming.

Specifically, first, the magnetic fields in the x, y, and z directions are measured at each of the two measurement points. This gives 6 independent measurements. Next, when the error between the value of the magnetic field generated by the current dipole at the measurement point and the actual measured value is ε _i , the error sum of squares Σ
With {ε _i } ² as the objective function, the parameters are searched by using the numerical solution method so as to minimize it.

In this embodiment, the so-called "iteration method" is used.
The iterative method is a method of searching for a numerical solution by the following procedure. That is, first, "initial setting" is performed as the first procedure. The initial setting refers to, for example, giving the value of the initial point x _o at k = 0 among the variables x _k . Next, as a second procedure, when a predetermined stop condition is satisfied is considered a solution that x _k.
If there is no x _k that satisfies the predetermined stop condition, the process proceeds to the next third procedure. In the third procedure, the search direction d _k is determined. Next, in a fourth procedure, the “step width α _k ” in the d _k direction is _obtained by a “straight line search method” or the like. Next, in the fifth procedure, x _{k + 1} = x _k + α _k · d _k ............ (2). Then, as a sixth procedure, k = k + 1, and the above-described second and subsequent procedures are executed again.

The "stop condition" in the second step of the above iterative method is the magnitude of the gradient vector ‖ ▽ f (x _k ) ‖.
And the sequence of points {x _k} of variation ‖x _k -x _k-1 ‖ has converged to a solution for determining Once decreased to a certain extent, and often considered. As an example of the above iterative method, first, the “steepest descent method (Stee
pest Descent Method) ", but since the gradient vector of the objective function indicates the direction that maximizes the function locally, if you proceed in the opposite direction,
This is based on the idea that the value of f (x) could be reduced along the maximum slope. According to this steepest descent method, the k-th search vector d _k is given by the following equation: d _k = −∇f (x _k ) ... (3) However, the above search direction is not always the best search strategy when searching for a global solution, and often stagnates on the way. The steepest descent method guarantees global convergence if a straight line search is performed well, but has the drawback that the convergence speed is very slow.

As another method, "Newton method (Newton method)
Method)). Newton's method uses the objective function x
minimum of second-order approximation model function _{f (x k + d) ≒} f (x k) + ▽ f (x k) T d + (1/2) d T ▽ 2 f (x k) d ... (4) with _k The direction toward the point is selected as the search vector. That is, the k-th search direction is obtained by solving the simultaneous linear equations ∇ ² f (x _k ) d = -∇f (x _k ) ... (5). By using this search direction, local quadratic convergence is realized.

However, the Newton's method has a drawback in that a "Hesse matrix" of a function is required, and it takes a great deal of labor to analytically calculate this Hessian matrix. It also has the disadvantage that global convergence cannot be guaranteed. Therefore, a numerical solution that can make up for the shortcomings while utilizing the advantages of the steepest descent method and the Newton method has been sought. Widely used.

The position and the direction of the current dipole estimated by the above method are the position and the direction of the current of the thunderbolt to be obtained.
In this case, the lightning current reverse estimating device 7 corresponds to the lightning current reverse estimating means.

Then, from the above-mentioned reverse estimated current value and cloud data, the thundercloud electric charge distribution calculation device 8 calculates the distribution of positive and negative electric charges e ⁺ and e ⁻ in the thundercloud C, and a lightning strike position / direction prediction process is performed. Send to device 10. In this case, the in-cloud charge distribution calculation device 8 corresponds to an in-cloud charge distribution calculation means.

In parallel with the above analysis, the ground potential change distribution calculating device 9 uses the data such as the ground potential or magnetism measured and input by the ground potential measuring sensors 3 _{1 to} 3 _n to
The ground current (current flowing on the ground surface G) I _G is calculated, the distribution of changes in the ground potential with respect to the thundercloud C that is currently being monitored is captured, and sent to the lightning strike position / direction prediction processing device 10. here,
The ground potential change distribution calculating device 9 corresponds to the ground potential change distribution calculating means.

Finally, the lightning strike position / direction prediction processing device 10 collects the transmitted motion data of the thundercloud C, structural data inside the thundercloud, charge distribution data in the thundercloud, ground potential change analysis data, and the like. Based on the comprehensive prediction process,
In the currently monitored thunder cloud C, the position of the ground G where the lightning strike is most likely to occur, the expected discharge position from the thunder cloud C, the direction of the expected discharge current, and the like are determined. The lightning strike position / direction prediction processing device 10 corresponds to lightning strike prediction means.

The lightning strike position / direction prediction processing device 10
Provides the above-described lightning strike prediction calculation information to other lightning protection systems or the like, or outputs image display output from the image display device 11 or print output from the print output device 12 as “lightning protection”. "Warning" is issued.

With the above-mentioned lightning detection method or lightning detection device, it is possible to predict lightning strikes to ground facilities such as factories and chemical plants and to prevent lightning. In addition, it is also possible to predict lightning strikes and lightning strikes on aircraft at airports.

The present invention can be further developed and applied. That is, by the above lightning strike prediction system 100,
Since it becomes possible to accurately predict the location and time of a lightning strike, a laser beam, a rocket, etc. will trigger the release of the energy of the thunderstorm, and the emitted energy will be stored by energy storage technology such as a superconducting ring. A power storage system can be constructed, and it is possible to effectively utilize the electric energy of thunderbolt.

In particular, according to the present invention, if the position of the ground point G at which lightning is most likely to occur, the discharge position in the cloud C at that time, and the direction of the discharge current can be determined from the charge distribution and the ground potential distribution in the cloud, It is possible to provide control information to a lightning protection system such as a laser beam and information on the polarity of electric charge to a power storage system.

The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the claims of the present invention, and any device having the same function and effect can be realized by the present invention. It is included in the technical scope of the invention.

For example, in the lightning detection method and the lightning detection device of the above-described embodiment, an example in which a weather radar, an SQUID sensor, a current measuring sensor, etc. are installed on the ground G to predict a lightning strike on land has been described. This is based on exactly the same principle as the prediction of lightning strikes and lightning strikes on ships during navigation,
Alternatively, it is possible to perform lightning strike prediction and lightning protection for an aircraft in flight. In these cases, instead of analyzing the ground current or the ground potential, the surface current of the hull or the body or the potential of the hull or the body is analyzed.

[0037]

As described above, according to the present invention having the above-mentioned configuration, the magnetic field generated by the leakage current or the cloud discharge which is a preceding phenomenon of a lightning strike is provided by the magnetic detection means such as the SQUID sensor. It can be detected as a quantity data, and the direction of the current of the thunderbolt can be inversely estimated from this vector data and combined with the observation data such as the cloud structure, such as the cross-sectional shape and the wind speed, by the weather detection means such as the weather radar. , The charge distribution in the cloud can be calculated. To the above information, add the ground potential change distribution for the thundercloud, which is calculated from the ground current obtained by measuring the ground potential difference or magnetism, and make a comprehensive judgment from the above cloud charge distribution and ground potential change distribution. This makes it possible to predict the ground position where the lightning strike probability is maximum, the position of the cloud discharge destination at that time, and the direction of the discharge current. This has the advantage that it is possible to prevent damage from lightning strikes at airports, factories, and the like.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a procedure of a lightning detection method that is a first embodiment of the present invention.

FIG. 2 is a block diagram showing the overall configuration of a lightning strike prediction system that is a second embodiment of the present invention.

FIG. 3 is a conceptual diagram illustrating the principle of reverse current estimation in FIG. 1 or FIG.

[Explanation of symbols]

1 ₁ to 1 _n weather radar 2 ₁ to 2 _n SQUID sensor 3 ₁ to 3 _n locations amperometric sensor 5 cloud motion-cloud structure analysis apparatus 6 field vector analyzer 7 lightning current reverse estimating device 8 thundercloud the charge distribution calculation device 9 ground potential change distribution calculating device 10 lightning strike position and direction prediction processor 11 the image display device 12 print output device 20 analysis system 100 lightning forecast system C thundercloud D discharge e ^+, e ^- the charge G earth I _G land current

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takanori Komuro 2-1200 Inzai Gakuendai, Inzai-cho, Inba-gun, Chiba Inside the Superconducting Sensor Laboratory Co., Ltd. Tai 2-1200 In the superconducting sensor laboratory (72) Inventor Yasuhiro Haruta Takenishi Gakuen, Inzai-cho, Inba-gun, Chiba Tai 2-1200 Inside the superconducting sensor laboratory Examiner Shinichi Nagai

Claims (2)

(57) [Claims] 1. A first step of detecting cloud data relating to the internal structure and motion characteristics of clouds by a meteorological detection means, and a magnetic field generated by a magnetic detection means for generating a magnetic field associated with a leakage current or an aerial discharge phenomenon which is a preceding phenomenon of a lightning strike. In the cloud of interest from the second step of detecting as vector data, the third step of inversely estimating the direction of the current of the lightning from the magnetic field vector data, and the cloud data and the inversely estimated current direction. The fourth step of calculating the electric charge distribution of the ground, and the fifth step of calculating the ground current by measuring the ground potential difference or magnetism to calculate the change distribution of the ground potential with respect to the thundercloud. The cloud charge distribution and the ground potential. From the change distribution, the ground position where the probability of a lightning strike is the maximum, and the sixth step of determining the position of the discharge in the cloud and the direction of the current in that case, Lightning detection method according to claim. 2. Meteorological detection means for detecting cloud data relating to cloud internal structure and movement properties, and magnetic detection means for detecting magnetic field generated as a result of leakage current or aerial discharge phenomenon, which is a preceding phenomenon of lightning strike, as magnetic field vector data. And a charge current inverse estimation means for inversely estimating the current direction of the lightning current from the magnetic field vector data, and a charge distribution in the cloud of interest from the cloud data and the inversely estimated current direction. An electric charge distribution calculation means in the cloud, an earth potential change distribution calculation means for calculating an earth current change by measuring an electric potential difference or magnetism on the ground to calculate an electric potential change distribution with respect to a thundercloud, the in-cloud electric charge distribution and the earth potential A lightning strike characterized by having a ground position where the probability of a lightning strike is maximum based on the change distribution and a lightning strike prediction means for determining the position of discharge in the cloud and the direction of the current in that case. Detection equipment.