Open AccessReply [to “Comment on ‘Error made in reports of main field decay’”]
Author(s) -
Campbell Wallace H.
Publication year - 2004
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2004eo370005
Subject(s) - earth's magnetic field , spherical coordinate system , spherical harmonics , radius , longitude , field (mathematics) , center (category theory) , physics , surface (topology) , geographic coordinate system , gauss , prolate spheroidal coordinates , geodesy , latitude , mathematical analysis , magnetic field , geometry , orthogonal coordinates , mathematics , geology , computer science , astronomy , quantum mechanics , chemistry , computer security , pure mathematics , crystallography
I thank Maus et al. for providing this opportunity to explain spherical harmonic analysis (SHA) methods to our Eos readers. Gauss devised the SHA as a means for separating the external and internal geomagnetic field contributions at an analysis spherical surface. The SHA starts with the selection of an analysis center and axis through that center defining the study coordinates of longitude Φ, latitude θ, and radius r of the analysis sphere. Using Maxwell's equations, the three orthogonal geomagnetic field components at the analysis spherical surface are converted to equivalent potential function values to which two special series of terms are then fitted.