Hi Jay, that is the way I read it too. What you have to remember is that I
was using the Kyoto University figures at that time and that source was
reading at least 30nT higher than it is a present. There is also a lot of
evidence that Severe Geomagnetic storms (Kp=8 or 9) can lead to depressed
conditions over periods exceeding 28 days, even if there were no further
storms during that recoverly period. We have had a couple of minor storms
during this "recovery period" which has pegged it back a bit longer. The
Dst estimates do depend on how you derive them. The final values are only
posted after about 12 months, which is not a lot of use for real-time
propagation forecasting. It is difficult to measure or estimate as it is
about a 0.1% pertubation of the normal Geomagnetic field which is around
50,000nT. Colorado Univ and Kytot use different techniques which makes the
comparision interesting and helps when one or the other "seizes up".
In a way very good conditions are "anomolous", the best results are often
not after a very long quiet period. I am not sure why this is, but I
suspect it is possible that the E-layer could become slightly more
transparent after such a period. When Steve first started logging DCF39
(Dec/Jan 2003) this was seen and the best conditions occurred after some
minor geomagnetic activity when Kyoto reached a Dst estimate of zero. The
very best conditions are often seen for relatively short periods and are due
to enhancement when multiple paths reinforce. This is very likely what
happened to give Jean-Pierre an odd good nights reception recently. My
guess is we ain't fully recovered yet. Predicting good nights is difficult,
predicted poor ones is a lot easier !! As someone one said "Forecasting is
difficult.....particularly when it involves the future !" Still it keeps
the interest alive !!
Thanks for the comments....I hope it all comes back to us soon.
Cheers de Alan G3NYK
----- Original Message -----
From: Jay Rusgrove <[email protected]>
To: <[email protected]>
Sent: 12 January 2007 16:45
Subject: Re: LF: East to West TA attempts
All
2 cents...
I'm beginning to wonder if we're not looking at this backwards...
What I mean by that is, we're focusing on the current poor conditions as
abnormal. It appears abnormal when compared to the few good nights of
propagation we had about a week ago. Perhaps the few good nights were the
anomoly and not the current poor conditions.
My reason for saying this is that I've looked over the past couple years
notes on my TA receptions. In past years, assuming DST numbers today are
equivelenet to those in past years (which may or may not be the case), I
rarely if ever had a decent TA reception when the DST was in negative
territory.
To me, last weekend's good TA propagation with a DST of -20 or -15 would be
very unusual - using the past history as a guide.
2 cents...take it for what it's worth...
Jay W1VD / WD2XNS
----- Original Message -----
From: John Andrews
To: [email protected]
Sent: Friday, January 12, 2007 10:48 AM
Subject: Re: LF: East to West TA attempts
All,
I wouldn't recommend losing sleep trying to get signals across at this
point. Conditions are quite poor, and may not get better quickly, as the
flow from a coronal hole will kick in around Monday. Jay and I will
likely be running enough over the weekend to see how things are going.
I'd be hesitant to put a timetable on the recovery, as this week's
propagation crash is not fully understood.
John A.
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