Measurements of vertical electric field in a thunderstorm in a Chinese inland plateau

Abstract

A balloon-borne instrument was designed to measure the electric field in thunderstorms. One case of thunderstorm was observed in the Pingliang region (35.57° N, 106.59° E; and 1620m above sea level, a.s.l.) of a Chinese inland plateau, through penetration by the balloonborne sounding in the early period of the mature stage. Results showed that the sounding passed through seven predominant charge regions. A negative charge region with a depth of 800m located near the surface, and a positive charge region appeared in the warm cloud region; their mean charge densities were -0.44±0.136 and 0.43±0.103 nCm-3, respectively. Five charge regions existed in the region colder than 0°C, and charge polarity alternated in a vertical direction with a positive charge at the lowest region. The mean charge densities for these five regions were 0:40±0:037 nCm-3 (-9.5 to -4°C), -0:63± 0:0107 nCm-3 (-18 to -14°C), 0:35±0:063 nCm-3 (-27 to -18°C), -0:36±0:057 nCm-3 (-34 to -27°C), and 0:24±0:06 nCm-3 (-38 to -34°C). We speculated that the two independent positive charge regions in the lower portion are the same charge region with a weak charge density layer in the middle. The analysis showed that the real charge structure of the thunderstorm is more complex than the tripole model, and the lower dipole is the most intensive charge region in the thunderstorm.