I live in Central Minnesota and note Visible Aurora very frequently--mostly
because there are no outside lights within 1/2 mile of me (very little light
pollution). I've seen aurora that shimmers from the northern horizon to well
south of my Zenith. I've seen aurora that stays north of me, and aurora on
either side of me (E or W). A common event makes the N-S magnetic field lines
visible with waves of light intensity shooting from the western horizon to the
eastern horizon in just under a second. Very spectacular! I find very little
correlation between visible aurora and any sort of 'enhancement' of topband
propagation. In fact, just the opposite is true. If I can see it, there is
little, if any, topband propagation to anywhere. If it is a major auroral
event, the dummy load works just as well as the antenna. Attenuation on
Topband has been known to be higher during a visible event, but the ionosphere
can become similarly choked off without any visible evidence. A similar
physical mechanism is in play, but is often not visible.
Even on VHF, near as I can figure the 'visible' aurora has little to do with
propagation enhancement. I find better auroral propagation (read: longer
paths) on evenings when there is NO 'visible' aurora. I also find that visible
aurora is no guarantee that auroral propagation is even possible. When it is
visible, it tends to create fairly short paths on VHF (e.g. 150-400 miles.)
Ford-N0FP
ford@cmgate.com
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