Three-dimensional propagation characteristics of the upward connecting leaders in six negative tall-object flashes in Guangzhou
Three-dimensional propagation characteristics of the upward connecting leaders in six negative tall-object flashes in Guangzhou
复制标题
广州6个负高物体闪光向上连接先导的三维传播特性
DOI：
10.1016/j.atmosres.2014.06.008
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发表时间：
2014-11-01
影响因子：
5.5
通讯作者：
Zhang, Yijun
中科院分区：
文献类型：
--
作者：
Gao, Yan;Lu, Weitao;Zhang, Yijun
分析了广州地区高层建筑发生的6次向下负闪光现象。根据双站光学观测重建了三维闪电通道。对于每个重建的三维上行导流(UCL)通道，计算了其三维长度和速度。6个正UCL的三维长度值在180~818m之间，有38个三维速度值是结合三维UCL通道和高速图像计算出来的。三维速度值在0.8到143x10(5)米S(-1)之间，其中4个速度值(11%，4/38)在10(6)米S(-1)数量级。为了进行比较，使用单站高速图像计算了相应的二维(2-D)参数。二维长度和二维速度的取值范围分别为14 7~610 m和0.3~10.6×10(5)m S(-1)。通过统计分析，我们确定三维速度的平均值是二维速度的1.3倍。当时间接近回程(RS)时，UCL的传播速度增加。S(-1)在10(6)m量级的四个三维速度值都出现在RS之前不到0.2ms。当三维长度小于300m时，77%(20/26)的相应三维速度值小于5×10(5)m S(-1)。当三维长度大于300m或UCL尖端高度大于650m时，相应的三维速度值均大于5×10(5)m S(-1)。(C)2014爱思唯尔B.V.保留所有权利。
Six downward negative flashes terminated on tall structures in Guangzhou are analyzed. The three-dimensional (3-D) lightning channels are reconstructed from dual-station optical observations. For each reconstructed 3-D upward connecting leader (UCL) channel, its 3-D length and speed are calculated. The 3-D length values of the six positive UCLs range from 180 to 818 m. There are 38 3-D speed values which are calculated combining the 3-D UCL channel and the high-speed images for the six UCLs. The 3-D speed values range from 0.8 to 143 x 10(5) m s(-1) and four of them (11%, 4/38) are on the order of 10(6) m s(-1). For comparison, the corresponding two-dimensional (2-D) parameters are calculated using the single-station high-speed images. The values of the 2-D length and 2-D speed range from 147 to 610 m and 0.3 to 10.6 x 10(5) m s(-1), respectively. From the statistical analysis, we determine that the average value of the 3-D speed is 1.3 times that of the 2-D speed. When the time is approaching the return stroke (RS), the propagation speed of the UCL is increasing. All of the four 3-D speed values on the order of 10(6) m s(-1) occur less than 0.2 ms prior to the RS. When the 3-D length is shorter than 300 m, 77% (20/26) of the corresponding 3-D speed values are smaller than 5 x 10(5) m s(-1). When the 3-D length is longer than 300 m or the UCL tip height is higher than 650 m, all of the corresponding 3-D speed values are faster than 5 x 10(5) m s(-1). (C) 2014 Elsevier B.V. All rights reserved.