Hi Roelof
I dont think there is any evidence of conditions "improving" just before a
Geomag. event, though what is probably more important is that it is the
longest current period since the last event. I find the best indicator is
the level of the Dst index which measured the charge trapped in the
Equatorial Ring current (the Van Allen belts). This leaks into the D-ragion,
increasing absorption and reducing night-time long distance signal levels
every time they pass through the ionosphere. Unfortunately this is not the
only answer, there is always the possibility of multipath fading. Comparing
the responses of several stations at different locations (where the path
lengths will be different) can help help with this.
I think Kiel was a bit pessimistic the Kp only reached 5. The K index is a
measure of the magnetic shock it does not really indicated changes in the
ionisation levels in the ionosphere. The Dst doesnt do that either, but I
believe it gives a measure of the quantity of ions and electrons circulating
in a "reservoir" which exchanges charge with the ionosphere. This is why I
believe the best way is to watch a reliable source (TX) regularly so that
you spot changes from "normal". It is easy to spot what will be bad nights
but not easy to name the good ones :-))
Alan G3NYK
----- Original Message -----
From: "Roelof Bakker" <[email protected]>
To: <[email protected]>
Sent: Thursday, November 03, 2011 4:25 PM
Subject: Re: LF: Re: Over the Pole - towards Eu
> Hello Alan,
>
> Last weekend propagation of Canadian NDB's was almost non existant.
> The night from Monday to Tuesday, propagation of northern stations was
> much improved.
> Much to my surprise, I had good aural copy of NDB PVQ, Put River/Dead
> Horse which transmits on 376 kHz and is located in Alaska.
>
> Tuesday afternoon the K-index as reported by Kiel rose to 7.
>
> Now my question: I and others have often observed improved propagation in
> the NDB band just before a solar event.
> Does this also happen on 136 kHz and is there a theory that explains this
> phenomenon?
>
> 73,
> Roelof Bakker, pa0rdt
>
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