John,
You ask for wisdom "does anyone know of the propagation mechanism to
explain this"
Simple answer is, living here in Scandivnavia, been on the bands from
1982, all I can tell is the Queen Aurora shakes her skirt so every now
and then there is some dust or glitter that opens up the path.
It is 'rather typical' the path is there, but it is more typical the
areas at each end are small.
That is, the opening must be from an area to an area there are
stations and then the stations must be on.
Then the most difficult part:
At least one of the stations must call CQ so the other has the rare
opportunity to answer the CQing station.
The enigma in this is how often there are stations calling CQ to a
completely empty band?
Well .. sometimes the rag-chewers reveal the opening.
Against many possible odds, we do encounter these openings every now and then.
Typical Old Timer answer at local clubs here is that this propagation
happens only during contests. This propagation does not exist outside
countest hours.
Reckon that is not the whole truth. There is more to it.
We can analyze SFI, solar wind parameters, K or A figures ...
Yeap. You guessed right.
73,
Jukka OH6LI
su 30. tammik. 2022 klo 22.28 John Geiger (af5cc2@gmail.com) kirjoitti:
>
> Something I have noticed during the ARRL DX contest, and other winter
> contests, as well as during casual DXing, maybe a LA/SM/OH contester will
> have a better explanation for this:
>
> This past Friday I worked a SM3 on 15m FT8 at 5:15pm local time (2315 UTC),
> well past the time that the path to Europe on 15 had closed. This isn't
> the first time I have had this occur. Over the past few years I have
> witnessed this before, stations from LA/SM/OH coming through on 15 and 17
> meters mid to late afternoon, several hours after the path to Europe had
> closed for that band. They haven't been coming in the whole time since the
> disappearance of the rest of Europe, it is like a new path opens up several
> hours later, but only to these regions. These areas in Europe will have
> been in darkness for several hours as well, dropping the MUF below 15 and
> 17 meters, but there they are.
>
> This is a winter phenomena I am discussing. I am very familiar with Europe
> coming in later at night on 15 and 17 during the summer months, especially
> during higher sunspot numbers.
>
> So does anyone know of the propagation mechanism to explain this-why this
> one part of Europe comes in several hours after the path to the rest of
> Europe has closed-and when it is well into darkness at their QTH? I am
> guessing it might have something to do with their location in the Auroral
> Zone and some sort of Aurora to F2 hookup, but that is just a guess.
>
> 73 John AF5CC
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