A Statistical Analysis of Total Lightning Flashes and Peak Current from High-Resolution ENTLN Measurements in South China during 2017

Abstract

In this study, the spatiotemporal characteristics of total lightning, including cloud-to-ground (CG) and intracloud (IC), flashes and the peak current of CG flashes are investigated using the observations from the Earth Networks Total Lightning Network (ENTLN) during 2017 over Guangdong Province and its adjacent offshore regions, where are the capital of lightning activity and convective rainfall in China. The ENTLN detects 2,825,558 IC and 569,104 CG flashes, accounting for 83.2% and 16.8% of annual-total lightning flashes, respectively, and they are distributed during 224 lightning days or 3316 lightning hours over the regions. The lightning activity peaks in June (IC) and July (CG) with a diurnal peak at 1500 LST. On average, about 70 lightning days with 20 flashes km−2yr−1 occur inland, and double offshore. High lightning days and flash density are found in the central and southwestern mountainous region, and the Guangdong-Hong Kong-Macao Greater Bay area, where convective activity is high. An analysis of the CG observations reveals that negative CG (NCG) produce an average of 1.96 strokes, with 5% of them having more than six return strokes. The peak currents of NCG strokes increase with increasing multiplicity. Results also show that the peak current and accumulated value of NCG flashes are the appropriate indicators to characterize the intensity of lightning activity in terms of spatiotemporal variations, especially in the mountainous region. It is concluded that IC observations provide more distinct spatial distribution of lightning activity than CG flashes; and those appropriate indicators should be used to represent the peak current of multi-stroke NCG flashes.