不同高度建筑物上的下行地闪回击特征

为了研究不同高度建筑物上发生的下行地闪回击特征差异，对2009—2012年广州高建筑物雷电观测试验中获取的能确认接地点高度的58次下行负极性地闪的综合同步观测资料进行对比分析。结果表明：接地点高度小于等于200m和接地点高度大于200m两类地闪的回击次数和回击间隔时间的差异不明显，但接地点高度大于200m的地闪的首次回击电流幅值、继后回击电流幅值、首次回击光强脉冲的10%~90%波前时间及10%波前~50%波后半宽时间、继后回击光强脉冲的10%~90%波前时间及10%波前~50%波后半宽时间的算术平均值 (几何平均值) 分别为接地点高度小于等于200 m地闪的1.8(2.1)，1.5(1.4)，7.4(7.4)，3.1(3.4)，4.6(4.3) 和2.4(3.6) 倍。

Characteristics of Downward Cloud to ground Lightning Return Strokes Occurring on Tall Structures with Different Heights

To study the difference between characteristics of lightning return strokes occurring on tall structures with different heights, comprehensive observations for 58 natural downward negative cloud-to-ground lightning flashes with confirmed grounding points are analyzed. When heights of grounding points are below 200 m, the arithmetic mean and geometric mean values for the number of strokes per flash, inter-stroke intervals, peak currents of the first strokes, peak currents of the subsequent strokes, 10%-90% rise times of the first stroke optical pulses, widths from 10% wave front to 50% wave tail of the first stroke optical pulses, 10%-90% rise times of the subsequent stroke optical pulses, and widths from the 10% wave front to the 50% wave tail of the subsequent stroke optical pulses are estimated to be about 3.7 and 1 (33 samples), 95 ms and 66 ms (15 flashes containing 95 strokes), -57.9 kA and-43.8 kA (30 samples), -34.1 kA and-30.8 kA (68 samples), 3.8 μs and 3.1 μs (17 samples), 38.1 μs and 32.5 μs (17 samples), 2.2 μs and 2.0 μs (19 samples), 52.9 μs and 35.0 μs (19 samples), while values are estimated to be about 2.6 and 1 (22 samples), 94 ms and 57 ms (10 flashes containing 41 strokes), -104.3 kA and-92.9 kA (24 samples), -50.1 kA and-42.6 kA (32 samples), 28.3 μs and 22.7 μs (13 samples), 119.8 μs and 110.5 μs (13 samples), 10.1 μs and 8.8 μs (4 samples), 126.5 μs and 124.8 μs (4 samples) when heights of grounding points are greater than 200 m. On the whole, the number of strokes per flash and inter-stroke intervals of flashes occurring on structures taller than 200 m and those lower than 200 m are close. But peak currents of the first strokes, peak currents of the subsequent strokes, 10%-90% rise times of the first stroke optical pulses, widths from 10% wave front to 50% wave tail of the first stroke optical pulses, 10%-90% rise times of the subsequent stroke optical pulses, widths from the 10% wave front to 50% wave tail of the subsequent stroke optical pulses for the flashes occurring on structures taller than 200 m are greater than those occurring on structures lower than 200 m, and arithmetic mean (geometric mean) values of the former are 1.8 (2.1), 1.5 (1.4), 7.4 (7.4), 3.1 (3.4), 4.6 (4.3), 2.4 (3.6) times of the latter.