Fast and Fine Location of Total Lightning from Low Frequency Signals Based on Deep-Learning Encoding Features

Self Cite

Monitoring lightning and its location is important for understanding thunderstorm activity and revealing lightning discharge mechanisms. This is often realized based on very low-frequency/low-frequency (VLF/LF) signals, very high-frequency (VHF) signals, and optical radiation signals generated during the lightning discharge process. The development of lightning monitoring and location technology worldwide has largely evolved from a single station to multiple stations, from the return strokes (RSs) of cloud-to-ground (CG) lightning flashes to total lightning flashes, from total lightning flashes to lightning discharge channels, and from ground-based lightning observations to satellite-based lightning observations, all of which have aided our understanding of atmospheric electricity. Lightning monitoring and positioning technology in China has kept up with international advances. In terms of lightning monitoring based on VLF/LF signals, single-station positioning technology has been developed, and a nationwide CG lightning detection network has been built since the end of the twentieth century. Research on total lightning flash positioning technology began at the beginning of the 21st century, and precision total lightning flash positioning technology has improved significantly over the last 10 years. In terms of positioning technology based on VHF signals, narrowband interferometers and wideband interferometers have been developed, and long-baseline radiation source positioning technology and continuous interferometers have been developed over the last ten years, significantly improving the channel characterization ability of lightning locations. In terms of lightning monitoring based on optical signals, China has for the first time developed lightning mapping imagers loaded by geosynchronous satellites, providing an important means for large-scale and all-weather lightning monitoring.

Section: Total Lightning Precision Location Technology Based On Vlf/l...mentioning

confidence: 99%

Advances in Lightning Monitoring and Location Technology Research in China

Zhang

Zou

et al. 2022

Self Cite

“…Equation ( 4) is a group of hyperbolic equations that can be solved by some iteration [23,25,26] or analytical algorithm [27,28]. Unfortunately, we cannot determine that all the observed TDOAs are due to a common discharge because there might have been flipping and superposition in the different receivers.…”

Section: Technical Notementioning

confidence: 99%

“…Li et al combined the TDOA technique and electromagnetic TR technique to image lightning channels [22]. In addition, the deep-learning technology has been introduced in the location of total lightning [23]. The ABA (A, B double time base) data acquisition system based on first input first output memory is adopted in a low frequency 3D lightning mapping network [24].…”

Section: Introductionmentioning

confidence: 99%

“…The lightning location based on the TOA technique can be roughly divided into two categories. The one works by solving a group of non-linear equations by some iteration [23,25,26] or analytical algorithm in principle [27,28], and the other adopts the numerical grid traverse algorithm (GTA), which builds a grid database first and then finds the grid point that matches the time differences [15,29]. Different from the iteration algorithm, the GTA does not need an initial value and is inherently accurate but has computing burdensome.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

3D Lightning Location Method Based on Range Difference Space Projection

Fan

Zhou

2022

Most lightning location networks obtain the position results by optimizing the goodness of fit to determine that all combinatorial time differences of arrivals (TDOAs) are due to a common discharge. This paper proposes a three-dimensional (3D) lightning location method based on range difference (RD) space projection. The proposed method projects all the measurements into the RD space, which has the space-invariant feature of the equivalence cell and can be partitioned soundly. Aiming at the problem of computational cost of the procedure of the projection, the hierarchical strategy is proposed to improve computational efficiency. The performance of the RD space projection based on the hierarchical strategy is analyzed via Monte-Carlo simulations. The results show that the proposed method can locate lightning sources in real time with high accuracy. The results also show that the location accuracy is limited by the level of the inherent time uncertainty, the layout, and the size of the receiver network. Under the fixed layout and size of the receiver network, and the fixed measurement noise uncertainty, the positioning precision cannot be improved more even if the grid step is small enough or the number of receivers is large enough.

“…Using these electromagnetic signals, which can penetrate clouds, many methods have been developed to locate the lightning sources. For example, for very-low-frequency (VLF) or low-frequency (LF) band signals, time of arrival (TOA) or time difference of arrival (TDOA) method (e.g., [2][3][4][5][6][7][8][9]) or artificial intelligence technology [10] have been applied. For electromagnetic signals in a very-high-frequency (VHF) band, lightning location methods are commonly carried out using the interferometry (INTF) or TDOA technique (e.g., [11][12][13][14][15]).…”

Section: Introductionmentioning

confidence: 99%

A New Hybrid Algorithm to Image Lightning Channels Combining the Time Difference of Arrival Technique and Electromagnetic Time Reversal Technique

Sun

Liu

et al. 2021

Very-high-frequency (VHF) electromagnetic signals have been well used to image lightning channels with high temporal and spatial resolution due to their capability to penetrate clouds. A lightning broadband VHF interferometer with three VHF antennas configured in a scalene-triangle shape has been installed in Lhasa since 2019, to detect the lightning VHF signals. Using the signals from the VHF interferometer, a new hybrid algorithm, called the TDOA-EMTR technique, combining the time difference of arrival (TDOA) and the electromagnetic time reversal (EMTR) technique is introduced to image the two-dimensional lightning channels. The TDOA technique is firstly applied to calculate the initial solutions for the whole lightning flash. According to the results by the TDOA method, the domain used for the EMTR technique is predetermined, and then the EMTR technique is operated to obtain the final positioning result. Unlike the original EMTR technique, the low-power frequency points for each time window are removed based on the FFT spectrum. Metrics used to filter noise events are adjusted. Detailed imaging results of a negative cloud-to-ground (CG) lightning flash and an intra-cloud (IC) lightning flash by the TDOA method and the TDOA-EMTR are presented. Compared with the original EMTR method, the positioning efficiency can be improved by more than a factor of 3 to 4, depending on the scope of the pre-determined domain. Results show that the new algorithm can obtain much weaker radiation sources and simultaneously occurring sources, compared with the TDOA method.