Characteristics of the initial stage and return stroke currents of rocket-triggered lightning flashes in southern China
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This study investigates the initial stage (IS) and return stroke (RS) currents of 50 triggered lightning flashes (TLFs) that were conducted in southern China. The IS of the negative TLFs has a longer duration, and larger average current, charge transfer, and action integral than those reported elsewhere, with geometric means (GMs) of 347.9 ms, 132.5 A, 45.1 C, and 10.0 × 103 A2 s, respectively. Two positive TLFs containing no RS have much greater average currents, charge transfers, and action integrals in the IS when compared with the negative TLFs. The RS has a greater peak current (17.2 kA; GM, same to below), charge transfer within 1 ms (1.3 C), and action integral within 1 ms (5.8 × 103 A2 s), and shorter 10% to 90% rise time (0.4 μs) than elsewhere. The peak current is prominently correlated with the rate of rise, charge transfer within 1 ms, and action integral within 1 ms. Furthermore, when the total duration of the RS and any following continuing currents is longer than 40 ms, the peak current, charge transfer within 1 ms, and action integral within 1 ms of the RS are seldom greater than 25 kA, 2.6 C, and 15 × 103 A2 s, respectively. It is indicated that TLFs containing RSs tend to have a longer duration but a smaller charge transfer during the IS than those without RS. The peak current of the RS is weakly correlated with its preceding silence period when there was no channel base current.
本研究针对中国南部开展的50次触发闪电闪击（triggered lightning flashes, TLFs）的初始阶段（initial stage, IS）与回击（return stroke, RS）电流展开分析。负地触发闪电闪击的初始阶段相较已有报道的同类事件，具备更长持续时长、更大平均电流、电荷转移量与作用积分，其几何均值（geometric means, GMs）分别为347.9 ms、132.5 A、45.1 C及10.0×10³ A²·s。两例不含回击的正地触发闪电闪击，其初始阶段的平均电流、电荷转移量与作用积分均显著高于负地触发闪电闪击。回击的峰值电流达17.2 kA（几何均值，下同）、1 ms内电荷转移量为1.3 C、1 ms内作用积分为5.8×10³ A²·s，且10%至90%上升时长仅为0.4 μs，各项参数均优于已有公开报道结果。回击峰值电流与电流上升率、1 ms内电荷转移量及1 ms内作用积分均呈显著相关。此外，当回击及后续持续电流总时长超过40 ms时，回击的峰值电流、1 ms内电荷转移量与1 ms内作用积分通常分别不超过25 kA、2.6 C及15×10³ A²·s。研究表明，含回击的触发闪电闪击在初始阶段持续时长更长，但电荷转移量却低于不含回击的触发闪电闪击。当回击前无通道底部电流时，回击峰值电流与此前的静默期呈弱相关。
