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Application of dipole modeling to magnetic anomalies
Author(s) -
Schmitz Dave,
Frayser J. B.,
Cain Joseph C.
Publication year - 1982
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl009i004p00307
Subject(s) - spherical harmonics , dipole , earth's magnetic field , magnetic dipole , geophysics , declination , magnetic anomaly , geodesy , residual , physics , spherical cap , geomagnetic pole , geology , moment (physics) , ridge , position (finance) , harmonic , computational physics , magnetic field , geometry , classical mechanics , mathematics , paleontology , finance , algorithm , astronomy , economics , quantum mechanics
A least‐squares technique is developed to obtain dipoles, which, when combined with an existing global field model, represent the relatively isolated magnetic anomalies which are residual to the high order (greater than 20) spherical harmonic internal geomagnetic field model. This combination of models (global spherical harmonic and local dipole) forms an efficient and compact representation of the geomagnetic field. The technique involves simultaneously solving for all three components of moment and of position of a dipole. The technique is applied to the mega‐anomaly west of Australia in a region about Broken Ridge, using data and spherical harmonic models separately constructed from POGO and MAGSAT spacecraft. The resulting equivalent dipoles agree fairly well and may be averaged to a 1 T·km³ dipole buried at 60 to 70 km depth near 32°S, 97°E oriented horizontally with a small (3±3°) east declination. This article contains supplementary material.