Abstract We analyzed in detail currents associated with upward unconnected leaders (UULs) initiated from the Kennedy Space Center (KSC) Industrial Area Tower (IAT). Current measurements of UULs in natural lightning are relatively rare and provide important insights into the development and propagation of upward leaders. Eight UULs were initiated from the KSC-IAT between August 1, 2018 and November 15, 2019. All UULs were positive as they occurred in response to downward negative leaders that attached to ground near the tower. The KSC Mesoscale Eastern Range Lightning Information System (MERLIN) located these nearby strokes at distances ranging from 185 to 783 m from the tower, with the median being 538 m. The peak current for these strokes ranged from 13 to 69.3 kA, with the median being 26.7 kA. From the perspective of charge transferred UULs can be considered to be a bipolar lightning phenomenon; they transferred negative charge to ground between the inception of their current and the current-polarity reversal, following which, they effectively transferred positive charge to ground. We labeled the former as the UUL development phase and the latter as the collapse phase. The median duration and charge transferred for the development phase were 789 μs and − 6.4 mC, respectively, and for the collapse phase were 388 μs and 4.7 mC, respectively. Overall, the net charge transferred to ground by UULs was negative. During the development phase, UUL-currents consisted of faster (total durations of the order of 10 μs) impulses overlaid on slower (millisecond-scale) “background” current. The background-to-peak UUL current-pulse amplitudes ranged from 3.4–289.2 A with the median being 30.1 A. The median pulse total duration and full-width at half-maximum (FWHM) were 14.1 μs and 4.9 μs, respectively. The median background-to-peak and 10-to-90% risetimes were 3.2 and 2.0 μs, respectively. Interpulse intervals ranged from 4.2–132.8 μs, with the median being 20 μs. Generally speaking, pulse amplitudes are larger, background currents are higher, and interpulse intervals are shorter at later times during UULs. It is likely that UULs with higher background currents at later times were closely approached by a downward leader branch versus the lower-current UULs which remained relatively stagnant.

中文翻译：

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从测得的电流推论向上的先导特性

摘要 我们详细分析了与从肯尼迪航天中心 (KSC) 工业区塔 (IAT) 发起的向上未连接领导者 (UUL) 相关的电流。目前对自然闪电中 UUL 的测量相对较少，并且为向上引导的发展和传播提供了重要的见解。2018 年 8 月 1 日至 2019 年 11 月 15 日期间，KSC-IAT 发起了 8 次 UUL。所有 UUL 都是积极的，因为它们是对附着在塔附近地面的向下负面领导者的回应。KSC 中尺度东部范围闪电信息系统 (MERLIN) 将这些附近的雷击定位在距离塔 185 到 783 m 的范围内，中位数为 538 m。这些中风的峰值电流范围为 13 至 69.3 kA，中值为 26.7 kA。从电荷转移的角度来看，UULs 可以认为是一种双极闪电现象；他们在电流开始和电流极性反转之间将负电荷转移到地面，随后，他们有效地将正电荷转移到地面。我们将前者标记为 UUL 开发阶段，将后者标记为崩溃阶段。显影阶段的中值持续时间和电荷转移分别为 789 μs 和 − 6.4 mC，塌陷阶段的中值分别为 388 μs 和 4.7 mC。总体而言，UUL 转移到地面的净电荷为负。在开发阶段，UUL 电流由覆盖在较慢（毫秒级）“背景”电流上的较快（总持续时间约为 10 微秒）脉冲组成。背景峰值 UUL 电流脉冲幅度范围为 3.4–289.2 A，中位数为 30.1 A。中位数脉冲总持续时间和半峰全宽 (FWHM) 分别为 14.1 μs 和 4.9 μs。中值背景峰值和 10% 至 90% 的上升时间分别为 3.2 和 2.0 μs。脉冲间隔范围为 4.2–132.8 μs，中位数为 20 μs。一般来说，脉冲幅度更大，背景电流更高，脉冲间隔在 UUL 后期更短。与保持相对停滞的低电流 UUL 相比，向下的先导分支可能会在稍后时间具有较高背景电流的 UUL 接近。分别。中值背景峰值和 10% 至 90% 的上升时间分别为 3.2 和 2.0 μs。脉冲间隔范围为 4.2–132.8 μs，中位数为 20 μs。一般来说，脉冲幅度更大，背景电流更高，脉冲间隔在 UUL 后期更短。与保持相对停滞的低电流 UUL 相比，向下的先导分支可能会在稍后时间具有较高背景电流的 UUL 接近。分别。中值背景峰值和 10% 至 90% 的上升时间分别为 3.2 和 2.0 μs。脉冲间隔范围为 4.2–132.8 μs，中位数为 20 μs。一般来说，脉冲幅度较大，背景电流较高，脉冲间隔在 UUL 后期更短。与保持相对停滞的低电流 UUL 相比，向下的先导分支可能会在稍后时间具有较高背景电流的 UUL 接近。