Analysis of a gigantic jet in southern China: morphology, meteorology, storm evolution, lightning and narrow bipolar events

<p>At about 22:43:30 BJT (Beijing Time = UTC + 8) on 13 August 2016, two amateur astronomers in Shikengkong, Guangdong province, and Jiahe County, Hunan province, respectively, fortunately captured a gigantic jet (GJ) event simultaneously and the GJ exact location could be triangulated. The parent thunderstorm was in a very humid environment [Precipitable Water (PWAT) in excess of 60 mm], featuring high convective available potential energy (CAPE) and weak 0-6 km vertical wind shear. The GJ occurred in the region with the coldest cloud top brightness temperature of −64 °C, suggesting the GJ was associated with strong vertical development of the thunderstorm. Vertical cross sections of radar reflectivity also show that the GJ occurred near the thunderstorm strong convection region as indicated by the results that a region of 25 dBZ (and 35 dBZ) in excess of the local tropopause (overshooting top in the parent thunderstorm) during a time window containing the GJ. The negative cloud-to-ground flashes dominated during the thunderstorm evolution. Three positive narrow bipolar events (NBEs) were detected within 30s before and after the GJ. It indicates that the NBEs were distributed between 11 and 13 km and occurred in the upper and middle layers of thunderstorm with radar reflectivity of 30-35 dBZ.</p>

Gigantic jet discharges evolve stepwise through the middle atmosphere

In 2002 it was discovered that a lightning discharge can rise out of the top of tropical thunderstorms and branch out spectacularly to the base of the ionosphere at 90 km altitude. Several dozens of such gigantic jets have been recorded or photographed since, but eluded capture by high-speed video cameras. Here we report on 4 gigantic jets recorded in Colombia at a temporal resolution of 200 µs to 1 ms. During the rising stage, one or more luminous steps are revealed at 32-40 km, before a continuous final jump of negative streamers to the ionosphere, starting in a bidirectional (bipolar) fashion. The subsequent trailing jet extends upward from the jump onset, with a current density well below that of lightning leaders. Magnetic field signals tracking the charge transfer and optical Geostationary Lightning Mapper data are now matched unambiguously to the precisely timed final jump process in a gigantic jet.