阅读说明：本技术 一种计算地闪准静电场能量的方法 (Method for calculating energy of quasi-electrostatic field of ground lightning ) 是由 马仪 文刚 马御棠 曹俊 王一帆 周仿荣 刘兴涛 孙董军 于 2021-09-23 设计创作，主要内容包括：本申请涉及雷电监测系统的技术领域,特别地,涉及一种计算地闪准静电场能量的方法。所述方法包括：接收地闪的电磁信号；将所述电磁信号传输至处理器进行处理,得到处理后的电磁信号；通过时域有限差分法FDTD,计算脉冲响应函数；通过将所述处理后的电磁信号与所述脉冲响应函数进行反卷积,得到地闪电流矩波形；通过对所述地闪电流矩波形进行时间积分,得到地闪准静电场能量,能够实现提高探测效率。(The application relates to the technical field of lightning monitoring systems, in particular to a method for calculating quasi-electrostatic field energy of ground lightning. The method comprises the following steps: receiving an electromagnetic signal of the ground flash; transmitting the electromagnetic signal to a processor for processing to obtain a processed electromagnetic signal; calculating an impulse response function by a finite difference time domain method (FDTD); deconvoluting the processed electromagnetic signal and the impulse response function to obtain a ground lightning current moment waveform; the ground lightning current moment waveform is subjected to time integration to obtain the energy of the ground lightning quasi-electrostatic field, so that the detection efficiency can be improved.)

1. A method of calculating the energy of a ground flash quasi-electrostatic field, comprising:

receiving an electromagnetic signal of the ground flash;

transmitting the electromagnetic signal to a processor for processing to obtain a processed electromagnetic signal;

calculating an impulse response function by a finite difference time domain method (FDTD);

deconvoluting the processed electromagnetic signal and the impulse response function to obtain a ground lightning current moment waveform;

and obtaining the energy of the quasi-electrostatic field of the ground lightning by performing time integration on the ground lightning current moment waveform.

2. The method of claim 1, wherein said transmitting said electromagnetic signal to a processor for processing comprises: by performing digital-to-analog conversion, noise and filtering processing on the electromagnetic signal.

3. The method of claim 1, wherein the ground flashover quasi-electrostatic field energy is obtained by analyzing the ground lightning current moment waveform.

4. A method of calculating the energy of the quasi-electrostatic field of a lightning according to claim 3, wherein the processed electromagnetic signal is deconvolved with the impulse response function by the specific expression:

wherein the content of the first and second substances,for lightning long-range horizontal magnetic fields, CM (τ) is the ground strike current moment to be solved, and h (τ) is the system response function.

5. The method of claim 1, wherein said impulse response function is an impulse response function of distant magnetic field propagation within 1kHz of earth-ionosphere cavity.

6. The method of claim 1, wherein said receiving the electromagnetic signal of the ground flash is preceded by: the occurrence position of the ground flash is determined by a ground flash positioning system.

7. The method of claim 1, wherein said electromagnetic signal is transmitted to said processor via a wireless communication module.

Technical Field

The present application relates to the field of lightning monitoring systems, and in particular, to a method of calculating the energy of a ground lightning quasi-electrostatic field.

Background

Cloud-ground lightning (ground lightning for short) is a common natural lightning phenomenon, and occurs in strong convection weather. When a local lightning occurs, the cloud typically delivers a high intensity pulsed current to the ground. It has been speculated that the interior of the cloud may contain a large number of branched horizontal channels that come into contact with the end of the channel when the strike-back front of the positively-biased flash reaches the end of the channel, and a large amount of positive charge enters the discharge channel to cause a continuous increase in current, thereby creating a pulsed current.

The amplitude of the pulse current and the continuous current is far smaller than that of the back-striking current, but the duration time of the pulse current and the continuous current is far longer than that of the back-striking current, so that a large amount of charges are transferred from the cloud to the ground in the process, and the ground flash discharge charge moment is continuously increased. The charge moment of the ground flash discharge is an important factor for determining the magnitude of the quasi-electrostatic field of the middle and high layers, and is closely related to the discharge phenomenon of the middle and high layers. Meanwhile, as the discharge duration is longer, the transferred charge amount is larger, the generated thermal effect is more serious, and the caused ground flash disaster is more serious, such as: forest fires caused by lightning strikes, damage of the lightning strikes to the power transmission lines and the like.

To determine the energy of the quasi-electrostatic field, it is necessary to discharge the moment of charge by calculation. In addition, the earth flash discharge charge moment plays an important role in recognizing and researching the characteristics of the earth flash and the meteorological conditions of the thunderstorm cloud. Therefore, it is desirable to provide a method for calculating the energy of the quasi-electrostatic field of the ground flash.

Disclosure of Invention

The application provides a method for calculating quasi-electrostatic field energy of a ground flash, which is used for realizing the calculation of an impulse response function through a Finite Difference Time Domain (FDTD) method; furthermore, the time integration is carried out on the current moment waveform to obtain the energy of the ground-lightning quasi-electrostatic field, so that the detection efficiency can be improved.

The embodiment of the application is realized as follows:

the embodiment of the application provides a method for calculating energy of a ground lightning quasi-electrostatic field, which comprises the following steps:

receiving an electromagnetic signal of the ground flash;

transmitting the electromagnetic signal to a processor for processing to obtain a processed electromagnetic signal;

calculating an impulse response function by a finite difference time domain method (FDTD);

deconvoluting the processed electromagnetic signal and the impulse response function to obtain a ground lightning current moment waveform;

and obtaining the energy of the quasi-electrostatic field of the ground lightning by performing time integration on the ground lightning current moment waveform.

In some embodiments, said transmitting said electromagnetic signal to a processor for processing comprises: by performing digital-to-analog conversion, noise and filtering processing on the electromagnetic signal.

In some embodiments, the ground bounce current moment is obtained by analyzing a current moment waveform of the ground bounce.

In some embodiments, the processed electromagnetic signal is deconvolved with the impulse response function, the deconvolution being expressed by:

wherein the content of the first and second substances,for lightning long-range horizontal magnetic fields, CM (τ) is the ground strike current moment to be solved, and h (τ) is the system response function.

In some embodiments, the impulse response function is an impulse response function of distant magnetic field propagation within 1kHz of the earth-ionosphere cavity.

In some embodiments, before receiving the electromagnetic signal of the ground flash, the method further includes: the occurrence position of the ground flash is determined by a ground flash positioning system.

In some embodiments, the electromagnetic signal is transmitted to the processor through a wireless communication module.

The method has the advantages that the electromagnetic signals are transmitted to the processor to be processed, and the processed electromagnetic signals are obtained; calculating an impulse response function by a finite difference time domain method (FDTD); deconvoluting the processed electromagnetic signal and the pulse response function to obtain a current moment waveform of the ground flashover; the current moment waveform is subjected to time integration to obtain the energy of the quasi-electrostatic field of the ground flash, so that the detection efficiency can be improved; meanwhile, technical support is provided for recognizing and researching the characteristics of the lightning and the meteorological conditions of the thunderstorm cloud.

Drawings

Specifically, in order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments are briefly described below, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without any creative effort.

FIG. 1 is a flow chart of a method for calculating the energy of a quasi-electrostatic field of a ground lightning according to an embodiment of the present application;

FIG. 2 is a schematic diagram showing a lightning moment waveform used in solving an impulse response in an embodiment of the present application;

fig. 3 shows a schematic diagram of a horizontal transverse magnetic field waveform generated at 1442km by one negative ground flashover in the embodiment of the application.

Detailed Description

Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the various embodiments of the present application is defined solely by the claims. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the present application.

Reference throughout this specification to "embodiments," "some embodiments," "one embodiment," or "an embodiment," etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in at least one other embodiment," or "in an embodiment," or the like, throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics shown or described in connection with one embodiment may be combined, in whole or in part, with the features, structures, or characteristics of one or more other embodiments, without limitation. Such modifications and variations are intended to be included within the scope of the present application.

Flow charts are used herein to illustrate operations performed by systems according to some embodiments of the present application. It should be expressly understood that the operations of the flow diagrams may be performed out of order, with precision. Rather, these operations may be performed in the reverse order or simultaneously. Also, one or more other operations may be added to the flowchart. One or more operations may be removed from the flowchart.

The present application provides a method for calculating the energy of a quasi-electrostatic field of a ground flash, which is described in detail below with reference to specific embodiments.

Fig. 1 shows a flow chart of a method for calculating the energy of the quasi-electrostatic field of the ground lightning in an embodiment of the present application.

In step 101, an electromagnetic signal of a ground flash is received.

In some embodiments, before receiving the electromagnetic signal of the ground flash, the method further includes: the occurrence position of the ground flash is determined by a ground flash positioning system.

In some embodiments, the lightning location system comprises a lightning locator. The lightning locator is also called a lightning monitoring locator, and is an automatic meteorological detection device for monitoring lightning occurrence, which is used for telemetering lightning return strike discharge parameters by utilizing the characteristics of sound, light and electromagnetic fields of lightning return strike radiation, and can detect the time, position, intensity, polarity and the like of the lightning occurrence. People are continuously dedicated to research on lightning detection devices and early detection and forecast technologies and methods of thunderstorm disasters.

It should be noted that: the electromagnetic signal of a lightning usually refers to the magnetic field waveform of a lightning.

In step 102, the electromagnetic signal is transmitted to a processor for processing, so as to obtain a processed electromagnetic signal.

In some embodiments, said transmitting said electromagnetic signal to a processor for processing comprises: by performing digital-to-analog conversion, noise and filtering processing on the electromagnetic signal.

In some embodiments, the electromagnetic signal is transmitted to the processor through a wireless communication module.

Among them, filtering (Wave filtering) is an operation of filtering out specific band frequencies in a signal, and is an important measure for suppressing and preventing interference.

In step 103, an impulse response function is calculated by a finite difference time domain method FDTD.

In some embodiments, the impulse response function is an impulse response function of distant magnetic field propagation within 1kHz of the earth-ionosphere cavity.

In some embodiments, the Finite-difference time-Domain (FDTD) method is a common method in the field of electromagnetic field computation. The basic idea is to use the central difference quotient to replace the first order partial derivative quotient of the field quantity to time and space, and to simulate the wave propagation process in time domain recursion, thereby obtaining the field distribution. FDTD direct discrete time domain wave equation does not need any derivation equation, so the application range of the FDTD direct discrete time domain wave equation is not limited by a mathematical model. The differential format of the method contains parameters of the medium, and various complex structures can be simulated only by giving corresponding parameters to each grid, which is a prominent advantage of a time domain finite difference method. In addition, because the finite difference time domain method adopts a stepping method to calculate, the simulation of various complex time domain broadband signals can be easily realized, and the time domain signal waveform of a certain point in space can be very conveniently obtained.

In step 104, a ground lightning current moment waveform is obtained by deconvolving the processed electromagnetic signal with the impulse response function.

In some embodiments, the processed electromagnetic signal is deconvolved with the impulse response function, the deconvolution being expressed by:

wherein the content of the first and second substances,for lightning long-range horizontal magnetic fields, CM (τ) is the ground strike current moment to be solved, and h (τ) is the system response function.

In some embodiments, the ground bounce current moment is obtained by analyzing a current moment waveform of the ground bounce. In some embodiments, the impulse response function is an impulse response function of distant magnetic field propagation within 1kHz of the earth-ionosphere cavity.

It should be noted that: when the waveform of the received lightning magnetic field is greatly different from the waveform of the impulse response, the discharge cannot be regarded as impulse-type discharge for the frequency band to be researched, and then the current moment waveform of the lightning needs to be inverted from the observed far-field waveform by using a deconvolution technology.

The method for solving the impulse response function of the remote magnetic field propagation within 1kHz in the earth-ionosphere cavity specifically comprises the following steps:

the impulse response of the system is the output when the unit impulse function (dickstra function δ) is input. An ideal unit impulse response has a value only at zero and all 0 values at the remaining non-zero points, but in practice there is no such function, which is often replaced by a narrow pulse with an integral of 1. According to the definition of the unit impulse response, the integral of the unit impulse function over the entire domain of definition should be 1. For the purposes of this application, a unit pulse moment of current is considered when the integral of the moment of current CM (τ) (i.e. the moment of charge) is 1 C.km. Therefore, when the charge moment integrated with time of the current moment added in FDTD is 1C · km, the obtained far-field waveform is the impulse response function (or called green function) of the earth-ionosphere waveguide cavity system.

FIG. 2 shows a schematic current moment waveform of a lightning used in solving an impulse response in an embodiment of the present application.

According to the definition of the unit impulse response, the integral of the unit impulse function over the whole definition domain should be 1, and when the integral of the pulse current moment (i.e. the charge moment) is 1C · m, it can be regarded as the unit pulse current moment. Therefore, when the pulse width of the current moment waveform added to FDTD is much less than 1ms and the charge moment thereof is 1C · m, the obtained far-field waveform is the unit impulse response of the earth-ionosphere waveguide system, as shown in fig. 1. Wherein in fig. 1, the pulse width is much less than 1 ms.

The state of the ionized layer can be regarded as constant within the one-time lightning discharge scale, although strong electromagnetic pulses or quasi-electrostatic fields generated by lightning can generate ionized layer electron density disturbance and electron temperature disturbance in the middle and upper atmosphere, the disturbances are only distributed at local positions in the ionized layer, and the influence on the long-distance and large-range lightning electromagnetic field propagation in a frequency band less than 1kHz can be ignored. Thus, the entire earth-ionosphere waveguide cavity can be assumed to be a linear time-invariant system. The input of the system is the current moment of the earth flash source, and the output is the distant earth flash electromagnetic field. Thus, the ground-flashback horizontal magnetic field observed at a distance of less than 1kHz is the convolution of the ground-lightning flow moment with the system response function, i.e.:

wherein the content of the first and second substances,for lightning long-range horizontal magnetic fields, CM (τ) is the ground strike current moment to be solved, h (τ) is the system response function。

In step 105, the time integral of the current moment waveform is performed to obtain the energy of the quasi-electrostatic field of the ground flash.

In some embodiments, the ground flash quasi-electrostatic field energy is obtained by time integrating the current moment waveform. Wherein, the energy of the quasi-electrostatic field of the ground flash is generally determined according to the charge moment of the ground flash.

In some embodiments, the ground lightning current moment waveform obtained by the method provided by the application is equivalent to a low-pass filtering result of the real lightning current moment. However, according to the characteristic of low-pass filtering, the difference between the integration result of the waveform after the low-pass filtering to the time and the integration result of the original waveform is small, so that the inversion of the lightning discharge charge moment by using the QTEM wave within 1kHz is reasonable.

It should be noted that: according to the analysis of the sensitivity of the impulse response function, the waveform of the impulse response is closely related to the ionospheric electron density distribution. The state of the ionosphere changes with time during the day, and there is a certain difference between the simulated impulse response and the impulse response under actual ionosphere conditions, which is the main reason for the difference between the earth lightning moment and the true earth lightning moment obtained by the method of the present application.

Fig. 3 shows a schematic diagram of a horizontal transverse magnetic field waveform generated at 1442km by one negative ground flashover in the embodiment of the application.

In some embodiments, the reliability of the method of the present application is verified by comparing the ground-lightning pulse charge moment obtained by the method of the present application with the results given in the data set, which is obtained from the lightning magnetic field waveform data set published on the network of gapeng et al, as shown in fig. 3. The detection station is located in Duke Forest (35.971 degrees N and 79.094 degrees E), the bandwidth of the very low frequency magnetic antenna is 50Hz to 30kHz, and the blue line is a waveform obtained by performing 500Hz low-pass filtering on a waveform measured by the very low frequency magnetic antenna. The method is used for simulating the impulse response under the typical night condition when the observation distance is 1442km, the impulse response is subjected to low-pass filtering at 500Hz, and the amplitude is enlarged by 455 times to obtain a red curve. As can be seen by comparison, the simulated waveform closely matches the measured waveform at the wave head portion. Therefore, a charge moment of about-455C-km within 500Hz of the ground flash discharge can be obtained, and the discharge scale is much less than 2ms (period corresponding to 500 Hz). And the ground flash pulse charge moment obtained by inverting the ULF frequency band magnetic antenna data in the data set is-459 C.km, and the reliability of the result obtained by the method provided by the application is verified again.

It should be noted that: the difference between the result obtained by the method provided by the application and the observed result in the wave tail part is mainly caused by the difference between the electron density of the ionized layer E adopted in the simulation and the electron density of the actual ionized layer.

Additionally, the order in which elements and sequences of the processes described herein are processed, the use of alphanumeric characters, or the use of other designations, is not intended to limit the order of the processes and methods described herein, unless explicitly claimed. While various presently contemplated embodiments of the invention have been discussed in the foregoing disclosure by way of example, it is to be understood that such detail is solely for that purpose and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements that are within the spirit and scope of the embodiments herein. For example, although the system components described above may be implemented by hardware devices, they may also be implemented by software-only solutions, such as installing the described system on an existing server or mobile device.

Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the embodiments. This method of disclosure, however, is not intended to require more features than are expressly recited in the claims. Indeed, the embodiments may be characterized as having less than all of the features of a single embodiment disclosed above.

The entire contents of each patent, patent application publication, and other material cited in this application, such as articles, books, specifications, publications, documents, and the like, are hereby incorporated by reference into this application. Except where the application is filed in a manner inconsistent or contrary to the present disclosure, and except where the claim is filed in its broadest scope (whether present or later appended to the application) as well. It is noted that the descriptions, definitions and/or use of terms in this application shall control if they are inconsistent or contrary to the statements and/or uses of the present application in the material attached to this application.