High Production of Gigantic Jets by a Thunderstorm Over Indian Ocean

Abstract

Thirteen gigantic jets (GJ) were observed on 12 February 2020, with a sensitive video camera located at Maïdo Observatory, La Réunion Island in Indian Ocean. They were produced within 68 min by nearby cells embedded in a convective system almost 500 km from Maïdo. The video imagery combined with the lightning activity from GLD360, the cloud top temperature (CTT), the ELF radiations, and the reanalysis of several meteorological parameters allow us to analyze their characteristics and their conditions of production. The altitudes for 12 GJ events are estimated between 85 and 89 km. All jets are of negative polarity and most of them preceded by a positive stroke/pulse in the discharge event. They are produced in sequences of a few minutes, during short pulses of convection within cells in phase of development and associated with dominant positive cloud‐to‐ground lightning flashes. The most luminous GJ produced the strongest Current Moment (CM) maximum, close to 280 kA km, and the largest Charge Moment Change (CMC). The CMCs associated with the GJ events range from about 1,000 C km to close to 5,500 C km, especially thanks to the CM during the trailing phase. Several GJ events exhibit a double structure with two jets slightly shifted in space, most of them occurring within the same field of the video imagery. The environment of this exceptional storm in terms of GJ production, exhibits extreme values of various parameters known to be favorable for GJ production, especially related to the warm cloud depth.