Outbreak of Gigantic Jets Over an Isolated Thunderstorm in South China

Abstract

On the evening of 18 August 2022, a sequence of five gigantic jets (GJs) were recorded within 7 min over an isolated coastal thunderstorm approximately 170 km to the southwest of Luoding County, Guangdong Province of China. The thunderstorm exhibited a higher −10°C isotherm altitude (500 m above average), a significant CAPE value (∼2,158 J/kg), and a combination of weak low-level wind shear (<3 m/s) and strong upper-level shear (∼14.5 m/s), composing favorable conditions for the GJ outbreak. GJs occurred during the developing-to-mature stage of the thunderstorm, characterized by the emergence of overshooting tops and cloud-top brightness temperatures below −70°C. Lightning activity was dominated by intracloud (IC) flashes, with IC frequency peaking at 47 events per 5-min interval around 20:10 UTC. High peak-current (>−30 kA) negative cloud-to-ground (−CG) flashes, which were active prior to 19:50 UTC, disappeared approximately 10–15 min before the GJ outbreak began. Additionally, all five GJs were likely preceded by narrow bipolar events, which are typically regarded as the onset signatures of GJ parent lightning, consistent with previous observations.