Electrical structure of a Qinghai–Tibet Plateau thunderstorm based on three-dimensional lightning mapping

Abstract

An isolated thunderstorm that occurred on August 6, 2009, in Datong, Qinghai province, China, was studied using a three-dimensional (3D) lightning mapping system distributed at seven stations. This thunderstorm exhibited a dominant positive electric field (corresponding to an overhead positive charge) at the ground. The 3D mapping results show that the thunderstorm took on an inverted dipole charge structure during its developing and mature stages from 09:08 UTC to 09:35 UTC when positive electric field was dominant. During the thunderstorm dissipating stage from 09:35 UTC to 09:58 UTC, the charge structure changed into four layers of positive, negative, positive and negative charges with heights of 5km (height from the ground), 4km, 3km and 1.8km, respectively. A comparison between the location of the lightning radiation sources and the radar echo shows that the radiation sources of the negative charge region corresponded to the region with radar reflectivity about 40dBZ in both the developing and mature stages, while for the positive charge radiation sources, they were located in the region with relative weak radar echo in the developing stage but in the mature stage they corresponded to the region with radar reflectivity greater than the 40dBZ.