A study on lightning discharge precursor by taking advantages of simple structure and observation easiness of Tibetan thunderstorms

利用西藏雷暴结构简单、易观测的特点进行闪电放电前兆研究

• 批准号: 17404003
• 负责人: WANG Daohong
• 金额: $ 4.29万
• 依托单位: Gifu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17404003/
• 关键词: Lightning; Forecast of lightning; Lightning precursor; Ground discharges; Thunderstorm electricity; 雷前兆現象

We have performed a lightning observation campaign in Lhasa city, Tibet plateau region of China in the summers of 2005 and 2006. We found1. Almost all Tibetan lightning occurred from late after noon to mid night. Thunderstorms differ greatly in lightning activity with some thunderstorms producing 20 flashes within one minute and some only a few even during their whole life period.2. Many of the thunderstorms exhibit positive dominant electric fields at the ground and tend to produce smaller ratio of cloud-to-ground (CG) discharges. Among the CG discharges recorded, nearly 90% of them are negative ones. In general summer thunderstorms, the favorite condition for triggering a CG discharge may be the presence of the opposite polarity of pocket charge beneath a main charge region. For Tibeuan thunderstorms, a negative pocket charge may not exist just beneath the main positive charge which produced the dominant positive electric fields. This may account for the small number of CG discharges.3. The lightning discharges are found to be initiated mainly at two heights : one is roughly 2 km and the other is 4 km above the ground. These results strongly suggest that the initial dominant leader of an intracloud discharge could be either a negative leader or a positive leader depending on its initial height. The large microsecond scale pulses usually observed at the initial stage of an intracloud discharge appeared to be generated when a negative leader is propagating within a positive charge region.4. The CG ratio differs much during different stages of thunderstorms which suggest that favorite electrical charge structures for producing CG exist.

我们于2005年和2006年夏季在中国西藏高原地区拉萨市进行了闪电观测活动。我们找到了1。几乎所有的西藏闪电都发生在午后到午夜。雷暴的闪电活动差异很大，有的雷暴在一分钟内产生20次闪电，有的雷暴在其整个生命周期内也只有几次.许多雷暴在地面上表现出正的主导电场，并倾向于产生较小的云地（CG）放电比。在所记录的CG放电中，近90%为负性放电。在一般的夏季雷暴中，触发CG放电的最佳条件可能是在主电荷区域下方存在相反极性的口袋电荷。对于西藏雷暴，负口袋电荷可能不存在于产生主导正电场的主正电荷之下。这可能是CG放电数量较少的原因。闪电放电主要发生在两个高度：一个高度约为2 km，另一个高度约为4 km。这些结果强烈地表明，云内放电的初始主导先导可以是负先导或正先导，取决于其初始高度。通常在云内放电的初始阶段观察到的微秒级大脉冲似乎是当负先导在正电荷区域内传播时产生的.在雷暴的不同阶段，CG比有很大的差异，这表明存在有利于产生CG的电荷结构。

项目成果

Electrical characteristics of an isolated Tibetan thunderstorm

西藏一次孤立雷暴的电学特征

• 发表时间: 2007
• 期刊: Proceedings of 13th International Conference on Atmospheric Electricity (In print)
• 作者: D.Wang;N.Takagi;T.Watanabe;T.Yuan;X.Qie;Y.Zhang
• 通讯作者: Y.Zhang

Observed characteristics of lightning occurred in Lhasa city, Tibet region of China

西藏地区拉萨市闪电观测特征

• 发表时间: 2007
• 期刊: Journal of Atmospherics Electricity Vol.27, No.1
• 作者: D.Wang;N.Takagi;T.Watanabe;T.Yuan;X.Qie;Y.Zhang
• 通讯作者: Y.Zhang

Characterization of the lightning occurred in Lhasa city, Tibet plateau region of China

西藏高原地区拉萨市闪电特征

• 发表时间: 2006
• 期刊: Proceedings of 28th International Conference on Lightning Protection
• 作者: D.Wang;K.Minamitani;H.Horibe;N.Takagi;T.Watanabe;T.Yuan;X.Qie;Y.Zhang;D.Sang
• 通讯作者: D.Sang