An improved ELF/VLF method for globally geolocating sprite‐producing lightning

Abstract

The majority of sprites, the most common of transient luminous events (TLEs) in the upper atmosphere, are associated with a sub‐class of positive cloud‐to‐ground lightning flashes (+CGs) whose characteristics are slowly being revealed. These +CGs produce extremely low frequency (ELF) and very low frequency (VLF) radiation detectable at great distances from the parent thunderstorm. During the STEPS field program in the United States, ELF/VLF transients associated with sprites were detected in the Negev Desert, Israel, some 11,000 km away. Within a two‐hour period on 4 July 2000, all of the sprites detected optically in the United States produced detectable ELF/VLF transients in Israel. All of these transients were of positive polarity (representing positive lightning). Using the VLF data to obtain the azimuth of the transients, and the ELF data to calculate the distance between the source and receiver, we remotely determined the position of the sprite‐forming lightning with an average locational error of 184 km (error of 1.6%).

The Severe Thunderstorm Electrification and Precipitation Study

“…Because STEPS featured a lightning mapper (the LMA) in close proximity to the Yucca Ridge Field Station, which recorded observations of TLEs, it provided an opportunity to distinguish sprite-parent +CGs (SP+CGs) from other lightning flashes. During STEPS, a half-dozen remote locations coordinated measurements of ELF transient signatures, allowing for both global-scale geolocation (Price et al 2002) and estimates of M of the SP+CGs (Hu et al 2002). LMA mapping of SP+CGs provided the height of the charge layers tapped by the CG strokes (Zg; Lyons et al 2003b).…”

ELF Electromagnetic Waves from Lightning: The Schumann Resonances

“…The physical mechanisms responsible for sprites and elves initiation are independent of the polarity of the lightning flash [127,128,[131][132][133][134]; however the vast majority of sprites are initiated by positive cloud-to-ground (CG) flashes [27,29,135,136]. These powerful positive flashes emit strong electromagnetic energy in the ELF range, indicative of continuing currents lasting over time scales of at least a few milliseconds [135], and thus can be detected in the SR band.…”

“…At a distance of 10 Mm from the source lightning (yellow curve), the electric field shows a minimum intensity at 8 and 20 Hz (n = 1, 3) while a maximum occurs at 14 and 26 Hz (n = 2, 4). Every distance has a specific spectral pattern in both the electric and magnetic fields, a characteristic often used in SR geolocation of intense lightning flashes using a single station [28,29,[36][37][38][39][40].…”

“…Finally, with the discovery of transient luminous events (TLEs) such as sprites, elves, jets, etc., it was shown that SR transient pulses are closely linked to the occurrence of transient luminous events-sprites and elves [27][28][29][30][31]. Hence, SR research is now also a major part of this new field of research related to upper atmospheric discharges.…”

“…The transients can be geolocated with SOD and/or source-bearing techniques, based on the relationship between the electric and the magnetic field components [28,29,36,39,40,94]. Source location techniques can be calibrated using the general location of flashes above continental regions [36,37], the proximity of cold cloud tops in visible and infra-red (IR) satellite images [95], global lightning measurements from space by the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) [39], and local measurements of lightning with ground networks, such as US National Lightning Detection Network in North America [29]. Geolocation of the source lightning using the single station SR methodology can be identified with an accuracy of ~1 Mm anywhere on the globe.…”