Workshop Report and Discussion paper: Geomagnetic reference fields; base-level and diurnal corrections to aeromagnetic data

Abstract

Geomagnetic reference fields and corrections to aeromagnetic data were the subjects of a discussion workshop held in Canberra on 1st December 1987. The proceedings of the workshop that are most relevant to aeromagnetic exploration in Australia are summarized in this article and supplemented with our additional comments. An accompanying paper (Barton, this issue) provides a more detailed exposition on the derivation and applications of global and regional geomagnetic reference fields. Initial discussions centred on recent developments in global and regional (Australian) modelling of the geomagnetic field, and applications and limitations on the use of available models. Attention then turned to the aeromagnetic 'diurnal' correction problem, the use of base-station and tie-line crossovers for making 'diurnal' corrections, continental and oceanic induction effects, the relative merits of magnetic gradiometer surveys, and ramifications of the modern trend towards the use of rapid sampling (£10 second) and high sensitivity (sub-nanotesla) survey techniques. Investigations into the spatial variability of magnetic field fluctuations using magnetometer arrays are needed both on a regional scale and on a local scale. The proposed Australia-wide array of geomagnetic stations (AWAGS) experiment is an example of the former. New methods of presenting the results of such investigations are also needed, for example in the form of a set of 'base-station reliability' maps of the region.