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A prescient cartoon in a field (aurora/solar-flare analogy) that comes and goes with time. Has anybody learned anything from this kind of exercise since this paper was written? At a rough guess 99% (or more) of all solar physicists could not define Cowling conductivity, and indeed many of them happily ignore the nature of current carriers completely. This is of course not so surprising in view of the distressing lack of in-situ coronal plasma measurements, but there you are.
In any case the author of this cartoon clearly shows the strong chromospheric perpendicular currents driven by the "collapse" of the emerged flux. The only wrinkle that could be added now would be the constraint on vertical current defined by the Melrose school (q.v.).
April 21, 2007