An overview of the external magnetic field with regard to magnetic surveys

Abstract

Abstract : This report sponsored by the Earth Physics Program of the Office of Naval Research, is an attempt to bring together in a coherent manner, for those involved in magnetic surveys, the relevant aspects of the external geomagnetic field. Although there are several excellant introductory texts on geomagnetism that treat much of this subject (most notably, Sugiura and Heppner, 1968; and Knecht, 1972) it was thought that there was a need to condense and present this and other supportive material in a form that would be more applicable to the objectives of magnetic surveys, as there is considerable interest in correcting magnetic surveys for the effects of the external field. Such efforts must start with a sufficiently detailed understanding of the geomagnetic environment in which magnetic survey data are collected and particularly of the various external field sources. Hopefully this report will serve to provide such an understanding. (Author)