Preliminary study on the source field mode of geomagnetic six-month-period variations |
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Authors: | P F Chen P C W Fung |
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Institution: | (1) Department of Physics, University of Hong Kong, Hong Kong |
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Abstract: | The monthly means of north component X of geomagnetic field from 16 observatories during 1984–1988 were analyzed using the
Sompi spectral analysis technique Most of these observatories are located in China. The analysis of the semiannual variations
indicates that the latitude has no apparent effect on the X component. This clearly implies that the source field mode of
semiannual variations cannot simply be described by using the p
1
0
mode. Using the p
1
0
mode to estimate the inductive scale lengthC in the semiannual period, the value ofC at each observatory would be biased significantly. The purpose of this study is to find which kind of modes is optimal for
estimating the values ofC corresponding to the semiannual variations. The results show that a composite mode, involving five terms P
n
0
(n = 1,, 5), might be a reasonable and acceptable one |
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Keywords: | geomagnetic semiannual variations Sompi spectral analysis source field mode geomagnetic inductive scale lengthC mantle conductivity |
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