Topband: auroral zone

[Carl K9LA]

W4ZV wrote:

> I think we were helped by a K-index of 4 at 1200 UTC.
> If you want to see what MAY be the source of
> refraction/reflection on this path, check out the following
> Webpage........It remains to be seen if the LP correlation to
> disturbed geomagnetic conditions holds, but so far it looks
> fairly good.

W4ZV and I have been exchanging e-mails on this subject, and indeed it is 
a very interesting hypothesis.  What seems to contradict this, though, 
are the observations of this path under quiet geomagnetic conditions.  An 
excellent example is the N6FF-to-A61AJ QSO of November 29, 1999 at 1440 
UTC.  N6FF heard A61AJ best on his southwest Beverage.  The Kp index was 
2 1 1 2 1 0 0 1 for each 3-hour interval beginning with 00-03 UTC.  
Understanding how this would fit in with W4ZV's hypothesis is a critical 
issue.  Digging into all-sky photos and electron density profiles at 
these high latitudes under quiet geomagnetic conditions looks like the 
way to go to better understand this.

A comment about those maps at the sec.noaa.gov/pmap web site - when the 
satellite makes a pass over a polar area, the particle detectors count 
the influx of 300 - 20,000 eV electrons.  From that, an estimate is made 
of the total power input by auroral particles to the polar region.  Then 
this estimate is put into one of ten classes ranging from less than 10 
gigawatts to over 500 gigawatts.  From this classification, a 
predetermined auroral picture is superimposed on the map.  Just like the 
DXAID pictures of the auroral oval, this region only shows the 
statistical location of visible aurora.  It does not say if there are 
electron density gradients or how big these gradients are if they are 
happening.  Of course the higher the k-index, the more certain one can be 
in saying that gradients are happening.

All of this is a real fascinating subject, and detailed observations, as 
the ones that have been posted recently for the XZ0A operation, are a big 
help.

Carl K9LA

"160m - where getting skewed is sometimes good"



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