7 / 2019-03-27 17:58:56

Observations of Lightning Discharges to the 356 m High Shenzhen Meteorological Tower

lightning to tall tower,lightning current waveform,electric and magnetic fields

To obtain firsthand lightning stroke current waveforms, a comprehensive lightning observation platform around the 356-m-high Shenzhen Meteorological Gradient Tower (SZMGT) was established in 2016. The platform includes: a lightning current measuring system on top of the tower, atmospheric electric field mills mounted at different height along the tower, and a main observation site located at 440 m away from the tower. Since then, a number of lightning discharges to the tower have been observed and analyzed. As the preliminary results, we present here: 1) two upward positive stepped-leaders initiated from the top of SZMGT, which the step lengths, time intervals and overall speeds are in the ranges of 0.5 – 4.4 m, 13.3 - 46.7 μs and 0.24 – 2.21 ×105 m/s, respectively; 2) two current waveforms of return strokes recorded on the top of SZMGT, which the peak currents are -110.4 kA and -87.7 kA respectively; and 3) a comparison of the electric field mill records at different height during a thunderstorm, which shows the enhancement effect of the electric field at higher part of the tower and the shielding effect of the electric field at lower part of the tower.