Every day, about one thousand thunderstorms occur around the world, producing about 45 lightning flashes per second. One prominent infrasound station of the International Monitoring System infrasound network of the Comprehensive Nuclear-Test-Ban Treaty Organization for studying lightning activity is in Ivory Coast, where the lightning rate of this region is relatively high. Infrasound defines acoustic waves with frequencies below 20 Hz, the lower limit of human hearing. Statistical results are presented in this paper based on infrasound measurements from 2004 to 2019. One-to-one association between infrasound detections from 0.5 to 5 Hz and lightning flashes detected by the World Wide Lightning Location Network within 500 km from the infrasound station is systematically investigated. Most of the infrasound signals detected at IS17 in this frequency band are due to thunder, even if the thunderstorms are located up to 500 km away from the station. A decay of the thunder amplitude with the flash distance, d, is found to scale as d^−0.717 for flashes within 100 km from the station, which holds for direct propagation. Interestingly, the stratospheric detections reflect a pattern in the annual azimuth variation, which is consistent with the equatorial stratospheric semi-annual oscillation.

中文翻译：

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科特迪瓦 15 年来的次声雷探测：定位、传播以及与平流层半年振荡的联系

每天，全世界大约会发生一千次雷暴，每秒产生大约 45 次闪电。全面禁止核试验条约组织国际监测系统次声网络中一个用于研究闪电活动的著名次声站位于象牙海岸，该地区的闪电率相对较高。次声定义了频率低于 20 Hz（人类听力下限）的声波。本文基于 2004 年至 2019 年的次声测量结果提供了统计结果。 系统地系统地系统地分析了 0.5 至 5 Hz 次声探测与全球闪电定位网络在距次声站 500 公里范围内探测到的闪电之间的一对一关联调查。在 IS17 在该频段检测到的大部分次声信号是由雷声引起的，即使雷暴位于距该站最远 500 公里的地方。发现雷电振幅随闪光距离 d 的衰减按 d 缩放距台站 100 公里范围内的^闪光为^−0.717，这适用于直接传播。有趣的是，平流层探测反映了年方位角变化的模式，这与赤道平流层半年振荡一致。