Parkinson's pointers’ potential perfidy!

Alan G. Jones*

*Corresponding author for this work

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

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 emphasized to aid in the qualitative assessment of induction in the region.

Original languageEnglish
Pages (from-to)1215-1224
Number of pages10
JournalGeophysical Journal of the Royal Astronomical Society
Volume87
Issue number3
DOIs
Publication statusPublished - 1986
Externally publishedYes

Keywords

  • conductivity anomalies
  • Geomagnetic Deep Sounding
  • Induction arrows
  • Parkinson arrows
  • Wiese vectors

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