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Spectral Analysis of Vector Magnetic Field ProfilesWe investigate the power spectra and cross spectra derived from the three components of the vector magnetic field measured on a straight horizontal path above a statistically stationary source. All of these spectra, which can be estimated from the recorded time series, are related to a single two-dimensional power spectral density via integrals that run in the across-track direction in the wavenumber domain. Thus the measured spectra must obey a number of strong constraints: for example, the sum of the two power spectral densities of the two horizontal field components equals the power spectral density of the vertical component at every wavenumber and the phase spectrum between the vertical and along-track components is always pi/2. These constraints provide powerful checks on the quality of the measured data; if they are violated, measurement or environmental noise should be suspected. The noise due to errors of orientation has a clear characteristic; both the power and phase spectra of the components differ from those of crustal signals, which makes orientation noise easy to detect and to quantify. The spectra of the crustal signals can be inverted to obtain information about the cross-track structure of the field. We illustrate these ideas using a high-altitude Project Magnet profile flown in the southeastern Pacific Ocean.
Document ID
20000013934
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Parker, Robert L.
(Scripps Institution of Oceanography La Jolla, CA United States)
OBrien, Michael S.
(Scripps Institution of Oceanography La Jolla, CA United States)
Date Acquired
August 19, 2013
Publication Date
November 10, 1997
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 102
Issue: B11
ISSN: 0148-0227
Subject Category
Geophysics
Report/Patent Number
Paper-97JB02130
Funding Number(s)
CONTRACT_GRANT: NAG5-2968
Distribution Limits
Public
Copyright
Other

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