Reference fields and global views: Australian and international geomagnetic reference fields

Abstract

By the mid 1960s there was general recognition of the need for an internationally accepted mathematical model of the earth's main field and its secular variation. Such a model would provide a standard for studies of magnetic anomalies, field residuals of external origin, the external form of the main field, the location of conjugate points, the long-term behaviour of the main field, and models for its origin. It was recognized that such a global model was attainable, although there was little prospect of agreement about higher order terms, representing regional and local detail of the field (Zmuda I971).