Studying lightning flashes using an autonomous multiband lightning detection system at Langmuir Lab*

Lightning flashes produce a wideband range of electromagnetic signals, going from low radio frequencies to optical and beyond. We developed a relatively mobile setup that can record lightning flashes in different spectral ranges in an autonomous manner. In radio, we record from near DC to 5 MHz (slow and fast electric field antennas). In the optical band, we record individual narrow bands centered at 337 nm (near UV), 777 nm, 844 nm, and 926 nm (near IR). We have also attached a high-speed camera running at 1000 fps to give us context, that is, to check if the flash happened in or out of the field of view. In the summer of 2024, we recorded a lightning flash containing 7 return strokes. On June 6, 2024 at 1:05:00 UTC with the new instrument, we observed that: the electric field peak happens at the same time as the optical emissions peak, the average time interval between return-strokes is 34.97 ms, and the flash had two different contact points to the ground (the first RS is out of the field of view). UV emissions happened before near IR emissions.