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Interaction with the lower ionosphere of electromagnetic pulses from lightning - Heating, attachment, and ionizationA Boltzmann formulation of the electron distribution function and Maxwell's equations for the EM fields are used to simulate the interaction of lightning radiated EM pulses with the lower ionosphere. Ionization and dissociative attachment induced by the heated electrons cause significant changes in the local electron density, N(e). Due to 'slow' field changes of typical lightning EM pulses over time scales of tens of microsec, the distribution function follows the quasi-equilibrium solution of the Boltzmann equation in the altitude range of interest (70 to 100 km). The EM pulse is simulated as a planar 100 microsec long single period oscillation of a 10 kHz wave injected at 70 km. Under nighttime conditions, individual pulses of intensity 10-20 V/m (normalized to 100 km horizontal distance) produce changes in N(e) of 1-30 percent while a sequence of pulses leads to strong modification of N(e) at altitudes less than 95 km. The N(e) changes produce a 'sharpening' of the lower ionospheric boundary by causing a reduction in electron density at 75-85 km (due to attachment) and a substantial increase at 85-95 km (due to ionization) (e.g., the scale height decreases by a factor of about 2 at about 85 km for a single 20 V/m EM pulse). No substantial N(e) changes occur during daytime.
Document ID
19930069908
Document Type
Reprint (Version printed in journal)
Authors
Taranenko, Y. N. (NASA Headquarters Washington, DC United States)
Inan, U. S. (NASA Headquarters Washington, DC United States)
Bell, T. F. (Stanford Univ. CA, United States)
Date Acquired
August 16, 2013
Publication Date
August 6, 1993
Publication Information
Publication: Geophysical Research Letters
Volume: 20
Issue: 15
ISSN: 0094-8276
Subject Category
GEOPHYSICS
Funding Number(s)
CONTRACT_GRANT: NAGW-2871
Distribution Limits
Public
Copyright
Other