EQUIVALENT SOURCE MAGNETIC DIPOLES REVISITED

Equivalent point source inversion in the rectangular coordinate system has been widely used to reduce satellite magnetic data collected at d ifferent altitudes to a common elevation over small areas. This method is based on the expression of the magnetic anomaly caused by a magnet ic dipole. Such an expression derived in a spherical coordinate system by von Frese et al. [1981] is found erroneous. We point out the error s in von Frese et al.'s [1981] formulas and present the correct expres sion for the magnetic field of a magnetic dipole in a spherical coordi nate system.