Topband: AstroAlert: Middle Latitude Auroral Activity Watch - 14-16Sept

[Ford Peterson]

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 at cmgate.com