February 11, 2013
Is There Gigantic Jet Event In Middle Latitude Region In Mainland China?
When talking about lightning, appearances of different lightning which occur along with thunderstorms will emerge in the minds of the people and these lightning occur in the troposphere. However, in addition to lightning in the troposphere, there are kinds of lightning discharges which occur above the thunderstorms. Up to now, lightning discharges above storms include sprite, elves (Emissions of Light and VLF perturbation due to EMP Sources, elves), Blue jet and Gigantic jet etc, and all of these discharges are totally named as Transient Luminous Events (TLEs). Gigantic jets were observed in America, Taiwan and Europe regions. Gigantic jet is sporadic compared with sprite, elves etc. Is there gigantic jet in middle latitude region in mainland China?
A recent study entitled "A gigantic jet event observed over a thunderstorm in mainland China", has been published in Chinese Science Bulletin, 2012, Vol 57(36). Detailed analysis of the observed gigantic jet and its associated storm were analyzed by using multiple data sets including low-light level observation, lightning location network, Doppler radar data and infrared weather images. This report was accomplished by the corresponding author Jing Yangï¼a research associate from Key Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences.Gigantic jet is a kind of large transient discharge which occurs above thunderstorms. It initiates from the thundercloud top and develops upward to the ionosphere, and connects the thunderstorm and ionosphere directly. Previous studies show that gigantic jet is often observed in tropical or subtropical regions, sometimes over winter thunderstorms. Is there gigantic jet in middle latitude region in mainland China? In addition, previous studies show that gigantic jet and sprites often occurred over the same storm. Is there any special case except this?
A gigantic jet event observed in middle latitude region in mainland China was first reported. The results show that the gigantic jet has tree-like shape, and the gigantic jet producing storm center located at about 35.6°N, 119.8°E. Different from other study that sprites and gigantic jets were produced by the same storm, two different storms produced two types of TLEs, that is, the gigantic jet producing storm produced only one gigantic jet event during its lifetime and five sprites were produced over another storm in this study. Also different from results in other studies that positive CGs dominated during a time period centered at gigantic jet, negative CGs dominated during a time period centered at the gigantic jet event and during most of the time in storm life in this study.
Gigantic jet starts from the thundercloud top and propagates upwards to the ionosphere, and it has a direct influence on the ionosphere potential and the electrical environment in the near space. Studies on this kind of discharge will provide an important protection for the space environment.
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