Publication XXX

Parkinson’s pointers’ potential perfidy!

A.G. Jones


The geomagnetic induction community often employs arrows to display, in a qualitative fashion, the effects of electromagnetic induction in a given region. It is widely accepted that the reversed real induction arrow - or ‘Parkinson’ arrow - points towards current concentrations, which are interpreted as zones of high internal electrical conductivity. In this note, the frequency characteristics of an embedded inhomogeneity are studied in detail, and it is demonstrated that the above assertion may be false, i.e. that at sufficiently high frequencies these arrows may point away from zones of high internal conductivity. This effect is small, and is shown to be the case whenever the surface observation site is at a location such that it is sensing the return current flow associated with the anomalous horizontal electric field. The use of anomalous transfer functions is


Geophysical Journal of the Royal Astronomical Society, 87, 1215-1224, 1987.

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Alan G Jones / 8 October 2007 /