Publication XXX
Parkinson’s pointers’ potential perfidy!
A.G. Jones
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
Source
Geophysical Journal of the Royal Astronomical Society, 87, 1215-1224, 1987.
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Alan G Jones / 8 October 2007 /
alan-at-cp.dias.ie