Analysis of the geomagnetic field by means of Cartesian components

Abstract

A method is presented for the determination of estimates of spherical harmonic coefficients of the internal and external components of the geomagnetic potential and also for the so-called non-potential field. Cartesian field components are employed in place of the usual local cartesian field components X, Y, Z. The functions P n m (cos θ) only need to be evaluated, and three sets of coefficients, i.e. non-potential, internal and external potential, are computed independently.