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

Download
Author
McKinley, Gary M.
Santos, Robert M.
Date
1980-12Advisor
Moose, Paul
Second Reader
Heinz, Otto
Metadata
Show full item recordAbstract
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.
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
Related items
Showing items related by title, author, creator and subject.
-
A digital analysis of internal waves at Ocean Station P.
Denham, Denny Jackson (Naval Postgraduate School, 1969);Methods of investigating internal waves from bathythermograph information are discussed. A series of 651 hourly observations taken at Ocean Station "P" is analyzed by two methods to determine the characteristics of the ... -
The Critical Richardson Number and Limits of Applicability of Local Similarity Theory in the Stable Boundary
Grachev, Andrey A.; Andreas, Edgar L.; Fairall, Christopher W.; Guest, Peter S.; Persson, P. Ola G. (2012);Measurements of atmospheric turbulence made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) are used to determine the limits of applicability of Monin-Obukhov similarity theory ... -
The diurnal cycle of high-frequency temperature variability at 0*, 140*W on seasonal and interannual time scales
Brainard, Russell E. (Monterey, California. Naval Postgraduate School, 1994-06);The diurnal cycle of high-frequency temperature fluctuations attributable to turbulence and internal waves in the upper central equatorial Pacific Ocean is found to persist over most of the period November 1983 - October ...