Statistical Analysis of Very Low Frequency Atmospheric Noise Caused by the Global Lightning Using Ground- Based Observations in China

摘要

Based on the very low frequency (VLF) signals observed on the ground in mid-latitude areas of China from February 2016 to February 2019, atmospheric noise in the 3-30 kHz band is investigated in detail. The statistical analysis indicates that the seasonal variations of the atmospheric noise of different bands are similar in the general trend but different in magnitude, the largest of which can reach 10 dB. According to the accuracy analysis of the atmospheric noise model by the Consultative Committee of International Radio (CCIR), despite the valid long-term variation of the atmospheric noise provided by the CCIR at the observation station, it overestimates the atmospheric noise level and thus, is unable to show the detailed characteristics of the short-term variation of the atmospheric noise. Combined with the global lightning observation, the correlation between atmospheric noise and global lightning activities is analyzed to find that the lightning within a range of 3,500 km can dominate the atmospheric noise at the observation site, along with distant lightning playing a minor role. Not only do the results deepen our understanding of the distribution of atmospheric noise in mid-latitudes in China, but they also reveal the correlation between atmospheric noise and global lightning, thereby benefiting the study of VLF signal propagation and its communication application.