Lightning monitoring methods include visual inspection, photography, electric field instrument, lightning counter spectrometer, pulse voltage recorder, satellite lightning detection, acoustic detection, and radar detection.
Ground-based detection technology:
1. Very low frequency (VLF / LF) positioning technology, features: large detection range; mainly detecting ground flashes; networking is required.
(1) Magnetic orientation method (MDF)
A pair of orthogonal loop magnetic field antennas placed vertically in the north-south direction and the east-west direction was used to measure the azimuth of lightning occurrence. The horizontal direction of the magnetic field can be obtained by comparing the amplitude and polarity of the signals induced on the two loop antennas.
(2) Time of Flight (TOA)
The time difference between the arrival of lightning electromagnetic pulses at different stations, a time difference between the two stations can form a hyperbola, and a time difference between the other two stations can also form another hyperbola. The intersection of the two hyperbola is the lightning strikeback position. .
(3) IMPACT (combination of MDF and TOA)
In view of the fact that the positioning error of the magnetic orientation method lightning positioning system is larger than that of the basic detection technology, the time difference method must have at least three detection stations to locate, and combine the two to form a time difference direction finding hybrid lightning positioning system. Its principle is: each detection The station not only detects the azimuth angle at which the return strike occurred, but also the precise time when the electromagnetic pulse waveform of the return strike arrived.
2. Very high frequency (VHF) positioning technology, features: higher positioning accuracy; higher time resolution; networking is required.
(1) Time-of-flight technology (VHF / TOA): Determine the location of the radiation source by determining the time difference between lightning radiation reaching two or several receivers that are far apart.
(2) Interference technology (VHF / IFT): The phase difference between signals arriving at different antennas is obtained by fast Fourier transform, then the phase difference is used to calculate the angle between the incident signal and the corresponding baseline, and finally the azimuth and elevation are calculated.
Spaceborne detection technology:
1. Spaceborne optical detection technology:
(1) Optical transient detector (OTD) on non-synchronous satellites in polar orbit: It is mounted on non-synchronous satellites in polar orbit, observing the intense light pulses from lightning in thunderstorm clouds vertically.
(2) Lightning imaging sensor (LIS) on a polar orbit non-synchronous satellite: It is mounted on a polar orbit non-synchronous satellite to observe the intense light pulses from lightning in a thunderstorm cloud vertically.
2. Spaceborne VHF detection technology: Use GPS satellite series, equipped with a VHF receiver similar to artificial satellite FORTE, and use DTOA (Time Difference to Achieve) technology to achieve global lightning location detection.