Optical observations of transient luminous events associated with winter thunderstorms near the coast of Israel
Optical observations of transient luminous events associated with winter thunderstorms near the coast of Israel
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DOI：
10.1016/j.atmosres.2008.06.018
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发表时间：
2009-02
影响因子：
5.5
通讯作者：
Y. Yair;C. Price;Michal Ganot;E. Greenberg;R. Yaniv;B. Ziv;Yosef Sherez;A. Devir;J. Bór;G. Sátori
中科院分区：
文献类型：
--
作者：
Y. Yair;C. Price;Michal Ganot;E. Greenberg;R. Yaniv;B. Ziv;Yosef Sherez;A. Devir;J. Bór;G. Sátori
我们报告了2005 - 2006年和2006 - 2007年在北半球冬季进行的两次观测活动的结果，旨在探测以色列和地中海东海岸附近冬季雷暴上空的瞬变发光事件（TLEs）。在31个不同的观测夜晚中的10个，我们发现了66个事件：56个精灵和10个精灵。探测距离从250公里到450公里不等。我们发现，精灵是由垂直尺寸为5-9公里、云顶温度为~ - 40°C的活跃单体产生的，这些单体嵌入在更大的层状降水云量中。这种结构与日本北陆地区冬季精灵的情况非常相似。与光学观测同步，在以色列和匈牙利的两个观测站记录了ELF数据，以确定和量化与TLEs相关的母闪电放电参数。这些台站分别位于距离东地中海500公里和2100公里的地方，而东地中海是大多数TLEs发生的地方。在光学观测到的TLE事件中，我们发现所有极低频信号都是由正的云对地闪光（+CGs）产生的，其中大部分记录在以色列（88%）和匈牙利（77%）。电荷矩变化的平均值为1400±600℃km，一些极端事件超过3500℃km，母体+CG的ELF瞬变与观测精灵的平均延迟时间为55 ms，柱精灵的延迟时间为42±34 ms，比胡萝卜精灵的延迟时间（68±34 ms）短。此外，基于ELF数据，在区域闪电活动中没有早期可识别的TLE发生前兆。从观测到的柱状精灵的空间形成来看，我们提出柱状精灵有时以三维圆形图案排列，从而映射了中间层中的瞬时电场。
We report the results of two observation campaigns conducted during the Northern Hemisphere winters of 2005–6 and 2006–7 aiming to detect transient luminous events (TLEs) above winter thunderstorms in the vicinity of Israel and the eastern coastline of the Mediterranean Sea. In 10 out of 31 different observation nights we detected 66 events: 56 sprites and 10 Elves. The detection ranges varied from 250 to 450 km. Sprites were found to be produced by active cells with a vertical dimension of 5–9 km and cloud top temperature ~−40 °C, embedded in a much larger matrix of stratiform precipitating cloudiness. This configuration closely resembles the conditions for winter sprites in the Hokuriku region of Japan. Synchronized with the optical observations, ELF data were recorded at two observation stations in Israel and Hungary in order to qualify and quantify parameters of the parent lightning discharge associated with the TLEs. These stations are located 500 km and 2100 km respectively from the Eastern Mediterranean Sea, where most TLEs occur. Among the optically observed TLE events, we found that all the ELF signals were produced solely by positive cloud-to-ground flashes (+CGs), most of which were recorded in Israel (88%) and Hungary (77%). Calculation of the Charge Moment Change showed average values of 1400±600 C km, with some extreme events exceeding 3500 C km. The average time delay between the ELF transient of the parent +CG and the observed sprites was 55 ms, with shorter delays for column sprites (42±34 ms) compared to carrot sprites (68±34). Furthermore, based on the ELF data, there were no early identifiable precursors to TLE occurrence in the regional lightning activity. From the spatial formation of the observed columniform sprites, we propose that columniform sprites are sometimes arranged in a 3-dimensional circular pattern, thus mapping the instantaneous electric field in the mesosphere.