Recent observations of electric fields in the ionosphere using various measurement techniques have led to important advances in the understanding of magnetosphere-ionosphere coupling. In particular the discovery of evidence for parallel electric fields in the altitude range 2, 000-10, 000km has an important impact on the question of auroral acceleration processes. More detailed mapping of large scale field-aligned current configurations on field lines penetrating the auroral oval are leading to more complete models for the generator processes in the outer magnetosphere which are associated with energy dissipation in the near-earth environment. Recent observations of significant electric fields equatorward of the auroral oval indicate that significant interaction between the magnetosphere and ionosphere takes place outside of the auroral oval. New techniques are presently being developed for more quantitative studies of magnetosphere-ionosphere coupling.

View full abstract

A profile of seven magnetometers, extending from a sea floor magnetometer at the edge of the continental shelf to one situated 300km inland, recorded geomagnetic variations during November/December 1976. The observations show a particularly uncomplicated coast effect variation. When the in-phase amplitude of the transfer function at 1 cycle per hour is plotted against distance from the continent edge it shows a striking resemblance to the results obtained on the south-east Australian coast by BENNETT and LILLEY (1971). This demonstrates that the hypothesis that the coast effect “signature” depends on the geological history of the continental material is a valid one. It encourages us to try to reproduce EVERETT and HYNDMAN'S (1967) “shield” curve with a profile of magnetometers across a shield area on the west coast of South Australia.

View full abstract