A FORTRAN SUBROUTINE TO DETERMINE THE COMPONENTS OF THE EARTH'S MAGNETIC FIELD AS A FUNCTION OF ALTITUDE AND GEOGRAPHIC COORDINATES FROM A SPHERICAL HARMONIC EXPANSION

摘要

This program evaluates the northerly, easterly, and vertical components [both in Gauss and Amp/m (MKS)] of the Earth's Magnetic Field at a specified height above some designated point on the surface of the earth. The mathematics of the program is derived directly from the spherical harmonic analysis of the earth's magnetic field as described by Jones and Melotte and also by J. C. Adams (see references at end of paper). Here it was assumed that the magnetic field is entirely of internal origin since the external field strength is less than approximately 0.1% of the internal field strength.