On the Accuracy of Ray-Theory Methods to Determine the Altitudes of Intracloud Electric Discharges and Ionospheric Reflections: Application to Narrow Bipolar Events

DOI: 
10.1029/2019JD032099
Publication date: 
02/06/2020
Main author: 
Li D.
IAA authors: 
Li, D.;Pérez-Invernón, F.J.;Luque, A.
Authors: 
Li D., Liu F., Pérez-Invernón F.J., Lu G., Qin Z., Zhu B., Luque A.
Journal: 
Journal of Geophysical Research: Atmospheres
Publication type: 
Article
Volume: 
125.0
Number: 
e2019JD032099
Abstract: 
Narrow bipolar events (NBEs) (also called narrow bipolar pulses [NBPs] or compact intracloud discharges [CIDs]) are energetic intracloud discharges characterized by narrow bipolar electromagnetic waveforms identified from ground-based very low frequency (VLF)/low-frequency (LF) observations. The simplified ray-theory method proposed by Smith et al. (1999, https://doi.org/10.1029/1998JD200045; 2004, https://doi.org/10.1029/2002RS002790) is widely used to infer the altitude of intracloud lightning and the effective (or virtual) reflection height of the ionosphere from VLF/LF signals. However, due to the large amount of high-frequency components in NBEs, the propagation effect of the electromagnetic fields for NBEs at large distance depends nontrivially on the geometry and the effective conductivity of the Earth-ionosphere waveguide (EIWG). In this study, we investigate the propagation of NBEs by using a full-wave Finite-Difference Time-Domain (FDTD) approach. The simulated results are compared with ground-based measurements at different distances in Southern China, and we assess the accuracy of the simplified ray-theory method in estimating the altitude of the NBE source and the effective reflection height of the ionosphere. It is noted that the evaluated NBE altitudes have a slight difference of about ±1 km when compared with the full-wave FDTD results, while the evaluated ionospheric reflection heights are found to be bigger than those obtained from FDTD model by about 5 km. ©2020. The Authors.
Database: 
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85084502598&doi=10.1029%2f2019JD032099&partnerID=40&md5=f1c5186914e3e3db16d77cd45ce0462f
Keywords: 
Earth-Ionosphere WaveGuide (EIWG); finite-difference time domain (FDTD); narrow bipolar events (NBEs); VLF/LF