Publication:
Power spectra of geomagnetic fluctuations between 0.4 and 40 Hz.

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Authors
Clayton, Frederick William
Subjects
Advisors
Heinz, O.
Date of Issue
1979-06
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
Power spectra of the fluctuations of the geomagnetic field were obtained for the frequency range of 0,4 - 40 Hz using an optically pumped Cesium vapor magnetometer. The measurements were made at Monterey, California in May, 1979. The spectra display a gradual decrease in slope at low frequencies with zero slope occurring between approximately 5 Hz and 15 Hz followed by a slight increase in slope. Data was collected at local midnight (0000-0200) , local morning (0800-1000) and local afternoon (1600-1800), The morning and afternoon spectra exhibit what is believed to be a Schumann resonance peak at 8.0 Hz. A peak at 2.2 Hz and its first harmonic (4.4 Hz) were also observed, but are believed to be a man-made phenomenon or a sensor related instrumentation effect. Considerable high frequency disturbances (20-40 Hz) were observed around local midnight and are believed to be ELF "Sf erics". A comparison between a magnetically disturbed day (Fredericksburg Index of 7+) and a quiet day (Fredericksburg Index of 2+) at the same time period (0800-1000) showed a difference of 7-9 dB in power spectral density.
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Thesis
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Department
Physics
Organization
Naval Postgraduate School
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Approved for public release; distribution is unlimited.
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