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Detection of elliptical polarization and mode splitting in discrete Schumann resonance excitationsElliptical polarization and mode splitting have been detected in the magnetic component of discrete, well defined Schumann resonance excitations. These ELF excitations, which are large electromagnetic transients of approximately 1 s duration, are called Q-bursts and typically occur every few minutes. They are believed to be the signature of the impulsive excitation of the earth-ionosphere cavity by ultra-large lightning currents. In this paper the magnetic polarization and spectral characteristics of four large Q-bursts are examined in detail using a new analysis technique. Two events display right-hand polarization and two display left-hand polarization. The theoretical polarization properties of the central and side multiplets of the Schumann resonances are used to define a local orthogonal coordinate system in the measurement frame in which these components may be separated. Maximum entropy spectrums computed separately for what are identified to be the central and side multiplets in this coordinate system show distinctly different eigenfrequencies for the lowest mode near 7.5 Hz. For the limited number of cases examined the magnitude of the line splitting detected using this technique is roughly 1.4-1.8 Hz, larger by nearly a factor of two than theoretical or observed values of the splitting previously reported. The frequencies of the side multiplets may lie either above or below the frequency of the central multiplet.
Document ID
19900025056
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Sentman, D. D.
(California, University Los Angeles, United States)
Date Acquired
August 14, 2013
Publication Date
June 1, 1989
Publication Information
Publication: Journal of Atmospheric and Terrestrial Physics
Volume: 51
ISSN: 0021-9169
Subject Category
Geophysics
Accession Number
90A12111
Funding Number(s)
CONTRACT_GRANT: W-7405-ENG-48
CONTRACT_GRANT: W-7405-ENG-36
CONTRACT_GRANT: NGL-05-007-004
Distribution Limits
Public
Copyright
Other

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