The Johannesburg Lightning Research Laboratory, Part 1: Characteristics of lightning currents to the Sentech Tower

摘要

? 2022This paper describes the first measurements of lightning currents from upward lightning events to a tall tower – the Sentech Tower – in Johannesburg, South Africa. The lightning activity in Johannesburg is described in context of other such sites around the world along with the high-speed camera setup and direct current measurement installation at the Sentech Tower, making up the project termed The Johannesburg Lightning Research Laboratory (JLRL). Measurements from the 2020–2021 lightning season are analysed in accordance with similar definitions used in other studies in Austria and Japan and the results are compared with the studies in these regions. A total of 42 lightning events to the tall tower are analysed. This resulted in 175 return strokes, 30 ICC fast pulses and 9 ICC Only events. The return stroke median current and median ICC fast pulse peak currents are comparable to the values seen in Austria and Japan at 7.51 kA and 3.75 kA, respectively. The median charge transfer is 41.36 C (35.51C for ICC Pulse events and 26.08C for ICC Only events) and is also similar to these studies. The return stroke multiplicity however, is higher for the Sentech Tower than elsewhere, with an average value of 6.41. Overall, the peak current distribution, charge transfer and inter-stroke time distribution showed agreement with the measurements made in Austria and Japan. However, the multiplicity of the events measured at the Sentech Tower appear to be twice as much as those seen in Austria and Japan.