XIANG Zheng,
LIN XianHao,
CHEN Wei et al
.2021.Global morphology of NWC and NAA very-low-frequency transmitter signals in the inner magnetosphere: A survey using Van Allen Probes EMFISIS measurements Chinese Journal of Geophysics(in Chinese),64(11): 3860-3869,doi: 10.6038/cjg2021P0131
基于范阿伦双星EMFISIS观测数据的NWC和NAA人工甚低频台站信号的内磁层全球统计分布
项正, 林显浩, 陈薇, 王勇, 陆鹏, 龚文颖, 马文琛, 花漫, 刘阳希子
武汉大学电子信息学院空间物理系, 武汉 430072
Global morphology of NWC and NAA very-low-frequency transmitter signals in the inner magnetosphere: A survey using Van Allen Probes EMFISIS measurements
XIANG Zheng, LIN XianHao, CHEN Wei, WANG Yong, LU Peng, GONG WenYing, MA WenChen, HUA Man, LIU YangXiZi
Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, China
Abstract:Signals from ground-based artificial VLF transmitters can penetrate through the ionosphere and leak into the Earth's magnetosphere, leading to inner radiation belt electrons precipitation into the atmosphere. It is of great scientific significance to study the global spatial distribution characteristics of VLF transmitter signals for analyzing the loss of radiation belt electrons. In this study, using 6 years high-quality wave measurements from Van Allen Probes during 2013-2018, we investigate the global distribution characteristics of NWC (19.8 kHz) and NAA (24.0 kHz) transmitter signals in detail, and systematically analyze the dependences of the transmitter signals distribution on the geographic latitude and longitude, L-shell, MLT, and geomagnetic activity level. The results suggest that the VLF transmitter signals in the inner magnetosphere mainly propagate along the magnetic field line across the station position. The averaged wave power intensities peak on the nightside of the Earth, and become more intensive in the winter months. The electron density is lower in the nightside and winter due to reduced sunlight, thus more wave powers leak into the magnetosphere. Meanwhile, the geomagnetic activities have slight influences on the global distributions of VLF transmitter signals. Based on these statistical observations, we obtain the global distribution characteristics of NWC and NAA transmitter signals intensities, which provide key information for further analysis of the wave-particles interactions between the VLF signals and radiation belt electrons.
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