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Early VLF perturbations caused by lightning EMP‐driven dissociative attachment
Author(s) -
Marshall R. A.,
Inan U. S.,
Chevalier T. W.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2008gl035358
Subject(s) - lightning (connector) , ionosphere , electromagnetic pulse , transmitter , amplitude , physics , signal (programming language) , very low frequency , electron density , electron , geophysics , optics , telecommunications , astronomy , computer science , power (physics) , channel (broadcasting) , quantum mechanics , programming language
We propose a new mechanism for lightning‐induced perturbations to VLF transmitter signals known as Early VLF events. This mechanism involves electron density changes due to electromagnetic pulses (EMP) from successive in‐cloud lightning discharges associated with cloud‐to‐ground discharges (CGs), which are likely the source of continuing current and much of the charge moment change in CGs. Through time‐domain modeling of the EMP we show that a sequence of pulses can produce appreciable density changes in the lower ionosphere, and that these changes are primarily electron losses through dissociative attachment to molecular oxygen. Modeling of the propagating VLF transmitter signal through the disturbed region shows that perturbed regions created by successive horizontal EMPs create measurable amplitude changes.