A model of the earth's magnetic field suitable for regional use

Abstract

A model of the earth's magnetic field is described, which is suitable for use over a limited area of the earth's surface. Coeficients for this model are derived from local observations consisting of observatory results, field measurements and aeromagnetic data. A process of deriving the coefficients has been devised which avoids problems with the stability of the solution. Finally, a system is described which allows the automated plotting of charts, based on the model. On the charts, the resolution is independent of the projection or scale being used.