Meteorological and Electrical Conditions of Two Mid-latitude Thunderstorms Producing Blue Discharges
Meteorological and Electrical Conditions of Two Mid-latitude Thunderstorms Producing Blue Discharges
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两次产生蓝色放电的中纬度雷暴的气象和电力条件
DOI：
10.1029/2020jd033648
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发表时间：
2021-04-20
影响因子：
4.4
通讯作者：
Zhou, Helin
中科院分区：
文献类型：
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作者：
Liu, Feifan;Zhu, Baoyou;Zhou, Helin
蓝色放电是雷暴顶部出现的一种罕见的向上放电。产生这种奇妙现象所需的有利气象条件和电荷结构仍然知之甚少。在这项研究中，我们报告了两个中纬度雷暴产生13个蓝色放电同时观察到的成像仪的精灵和高层大气闪电（ISUAL）和地面闪电探测阵列。在这两次雷暴中，蓝色放电都发生在最冷的云顶附近（约195 K），并聚集在对流涌附近的一个有界区域内，导致雷暴云顶（约18 km）越过平流层。从窄双极事件（NBEs）的源高度推断，母雷暴通常带电的主要中层负电荷和上部正电荷层集中在约15公里处。对流层顶附近的负NBE表明它们是云顶正电荷层和负屏蔽层之间的向上正放电。此外，在从空间观测到蓝色放电的同时，还观测到了16-18公里高度范围内负核爆的爆发。这表明在雷暴的这个高度上存在一个强的上部正层和强烈的对流。本文认为，在强对流上升气流的作用下，过冲雷暴云顶可能形成一个强而高的上部正电荷层，从而为启动向上的正蓝色放电创造了有利的电荷结构。关键点蓝色放电与过冲雷暴云顶附近的对流涌有关。强烈上升气流诱导的强上部正电荷层为蓝放电创造了有利的电荷结构条件
Blue discharges are one type of rarely observed upward discharge emerging from the top of thunderstorms. The favorable meteorological conditions and charge structures needed to produce this marvelous phenomenon are still poorly understood. In this study, we report on two midlatitude thunderstorms producing 13 blue discharges observed simultaneously by the Imager of Sprites and Upper Atmospheric Lightning (ISUAL) and ground-based lightning detection array. In these two thunderstorms, blue discharges always occurred in the vicinity of the coldest cloud top (similar to 195 K) and clustered within a bounded area near the convective surge, leading to the overshooting thundercloud top (reaching about 18 km) into the stratosphere. The parent thunderstorms were normally electrified with a main midlevel negative and an upper positive charge layer centered at about 15 km as inferred from source heights of narrow bipolar events (NBEs). The associated negative NBEs near the tropopause indicated that they are upward positive discharges initiated between the upper positive charge layer and the negative screening layer at the cloud top. In addition, the outbreak of negative NBEs in the altitude range of 16-18 km was observed in conjunction with blue discharges observed from space. This suggests that there exists a strong upper positive layer with an intense convection at this altitude of the thunderstorm. It is inferred that an overshooting thundercloud top with intense convective updraft could lead to a strong and high upper positive charge layer and therefore create favorable charge structures for initiating upward positive blue discharges.Key PointsBlue discharges are produced in association with the convection surge near overshooting thundercloud topsThe outbreak of negative narrow bipolar events (NBEs) is observed during the occurrence of blue dischargesStrong upper positive charge layer induced by intense updrafts would create favorable charge structure conditions for blue discharges