科研之友
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摘要
Gigantic jet (GJ) is a type of large-scaled transient discharge which occurs above thunderstorms. It connects the thunderstorms and ionosphere directly. Compared with the other transient luminous events (TLEs), gigantic jet is very difficult to be seen from the ground. We report a GJ event that was clearly recorded in eastern China (storm center located at 35.6A degrees N,119.8A degrees E, near the Huanghai Sea) at 20:16:22 (local time) on 12 August, 2010. It is by far the furthest from the equator ground-based GJ recorded over summer thunderstorm. The top altitude of this GJ was estimated to be about 89 km. The GJ-producing storm was a multi-cell thunderstorm and the GJ event occurred in the storm developing stage, with the lowest cloud-top brightness temperature about -73A degrees C and the maximum radar echo top around 17 km. Altitudes with reflectivity of 45 dBZ were estimated to reach 12-14 km. Different from results from other countries that positive CGs (Cloud-to-ground lightnings) dominated during a time period centered at GJ, our study shows that negative CGs dominated during a time period centered at the GJ event and during most of the storm lifetime in this study, indicating a diversity of 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 the other study that sprites and GJs were usually produced by the same storm, enriched the knowledge of GJ-producing storms. In addition, the GJ event in this study is located beyond the effective coverage area (30A degrees S-30A degrees N) of the ISUAL instruments onboard the FORMOSAT II satellite, and results of this study could be useful for GJ studies in the future.
- 出版日期2012-12
- 单位中国科学院大气物理研究所; 山东省气象科学研究所
