A gigantic jet event over a summer storm in China

摘要

Gigantic jet (GJ) is a kind of large transient discharge which occurs above thunderstorms, connecting the thunderstorms and ionosphere directly. Compared with other transient luminous events (TLEs), gigantic jet is very difficult to be recorded on the ground. One GJ event was clearly recorded over eastern China (storm center located at 35.6°N,119.8°E) in Chinese mainland near the Huanghai Sea at 20:16:22 on 12 August in 2010 (Beijing time). It is the first ground-based recorded GJ that is the most distant from the equator documented over summer thunderstorm so far. The top of the GJ on image were estimated to be about 89 km. The GJ-producing storm was a muti-cell thunderstorm and the GJ event occurred in the storm developing stage with lowest cloud-top brightness temperature of about -73 °C and maximum radar echo top of 17 km. Altitudes with reflectivity of 45 dBZ were estimated to reach 12~14 km. Different from results in other countries that positive CGs dominated during a time period centered at GJ, negative CGs dominated during a time period centered at the GJ event and during most of the time in storm life in this study, indicating a diversity in the lightning activity in the GJ-producing storms. It is interesting that two different storms produced two types of TLEs, that is, the GJ-producing storm only produced one GJ event during its lifetime and five sprites were produced over another storm, different from other study that sprites and GJs were produced by the same storm, enriched the knowledge of GJ-producing storms. In addition, the GJ event in this study located beyond the effective coverage area (30°S~30°N) of the ISUAL instruments onboard the FORMOSAT II satellite, and results of this study could be considered as a useful additional reference for GJ studies.