Characteristics of geomagnetic power spectra on land and sea in the period range 0.2 to 400 seconds

Loading...
Thumbnail Image
Authors
McKinley, Gary M.
Santos, Robert M.
Subjects
low frequency geomagnetic measurements
geomagnetic fluctuations
land and sea
Advisors
Moose, Paul
Date of Issue
1980-12
Date
December 1980
Publisher
Language
en_US
Abstract
Geomagnetic field fluctuations in the 0.025-5Hz range were measured with a Cesium vapor magnetometer on the sea floor in Monterey Bay, and at a remote land site. Correlation was found between the geomagnetic activity A-index and both the slope and relative magnitude of the power spectra. More active days showed a greater fall-off as frequency increased, and a higher level of the observed power spectra. Fluctuations averaging 0.1nT²/Hz were noted at the low frequencies, dropping to 10⁻⁵nT²/Hz at 1 Hz. Comparisons were made between the land/sea and day/night data to determine the sea and diurnal effects. In addition to swell induced fluctuations, the overall power spectra for sea data is 10-15 dB higher than land data. Diurnal shifts indicate a 20 second period increase in the nighttime Pc 3 fluctuations. Daytime intensity is generally 5 dB above the nighttime data, but with a crossover at 0.05Hz, the nighttime data then running 3 to 5 dB above the day. Further observations were made to determine the applicability of the magnetometer for non-seismic detection of nuclear blast.
Type
Thesis
Description
Series/Report No
Department
Physics and Chemistry
Organization
Naval Postgraduate School (U.S.)
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.
Collections