Hi Roelof, yes the geomagnetic acrivity does tend to peak about 12 to 18
months after the SSN cycle peak.
The decay after activity is a diffusion process (concentration driven) so
its a bit like dischaging a big cap it takes quite a while before the charge
dies to an insignificant level. Laurie G3AQC used to reckon between 10 and
14 days after an event was best. After 14 days there is an increasing
probability of another event. This was before we tied a label on Dst
properly. I used to use Kyoto but found it a bit "wild" and the real-time
data prone to erroneous input from some of the contribiting magnetometer
sites. Colorado Univ. is a "smoother" plot and does not suffer from later
data editing (as when Kyoto reject out of line results) being based on data
from the ACE satellite.
Alan
----- Original Message -----
From: "Roelof Bakker" <[email protected]>
To: <[email protected]>
Sent: Sunday, November 16, 2014 4:16 PM
Subject: Re: LF: CW 477.7 kHz
Hello Alan,
Propagation above 200 kHz has been rather poor the last month.
As soon as the band starts to recover, another blast from the sun fills
the glass to the rim once more, so to speak.
In my experience a quiet period of at least ten days is needed for good
propagation.
When you look at the graph of the Kyoto Dst, you will find that this has
not been the case for quite a while.
It is interesting to note that the last prolonged quiet period happened to
be in last July / start of August. On July 16, I logged 35 Canadian NDB's
as far inland as Toronto.
This was probably helped by grey line propagation, but none the less it
was quite exceptional.
At the moment it is really a struggle to hear more then five!
After the end of August, propagation has gone from bad to worse.
I often found that the start of January gives good propagation.
However, on the bright site, nobody knows what is going to happen next and
prove my assumptions completely wrong!
73,
Roelof, PAoRDT
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