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Re: LF: Re: Re: Poor conditions - the return of skywave

To: <[email protected]>
Subject: Re: LF: Re: Re: Poor conditions - the return of skywave
From: "Markus Vester" <[email protected]>
Date: Tue, 24 Mar 2015 21:10:57 +0100
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Hi Laurence,
 
interesting! Like Alan, I've wondered whether your N-S polar communication could have been through a field-aligned magnetospheric duct (referenced eg. by
http://www.researchgate.net/publication/257362707_The_magnetospheric_echo_box_--_A_type_of_long-delayed_echo_explained or http://folk.uio.no/sverre/papers/2009_MagnetoDucting-QST-LA3ZA.pdf, or in an article by Peter Martinez in Radcom Oct 2007). Wonder if you happened to find an unsusual delay - it could be more than half a second, so maybe just noticable in a voice circuit.
 
Best 73,
Markus (DF6NM)
 

From: Alan Melia
Sent: Tuesday, March 24, 2015 6:16 PM
Subject: LF: Re: Re: Poor conditions - the return of skywave

Hi Laurence you dont say what frequency the pole to pole path was? I wonder whether it might have been a sort of duct (trough its sometimes called) above the D-layer. The auroral hole might even help the signals into it :-))  Top band is supposed to exhibit that mode sometimes. Otherwise maybe a similar mode to whistler transmission, though your frequency might be too high for that.....the duct seems favourite.
 
The inside the auroral ring events suggest the precipitation is occuring at the latitude of the aurora, and this spreads out as it diffuses south. Hence its not quite so bad in Vancouver. I reckon your problem is launching that first hop through that.
 
It is not over yet, the Dst has started to dip again (Kyoto has gone up) I think this is the precursor to another coronal hole flow predicted for the 25th. I doesnt look too bad on the animation but it will add some electrons to the ring current and drag out the recovery a bit.
 
Alan
G3NYK
 
----- Original Message -----
Sent: Tuesday, March 24, 2015 3:30 PM
Subject: LF: Re: Poor conditions - the return of skywave

Thanks Alan - it certainly was a kicker up here -
 
Last night I had my first decode on 475kHz from WH2XGP since 17th from the "vanished" band - so this shows a slight improvement - very slight.
 
Its amazing to me that such relatively small changes in latitude have close to a logarithmic effect in losses. Its a different world here at 61N to my friends in Seattle just a 3 hour flight South, but again, and specific to this location -  these local and not so local ragged mountain ranges are breaking up skywave reflections too to my detriment, probably for signal coming in below 10 degrees here - and that's not helping at all either. I actually think this lat/geolat is actually worse than than up near the Geo Pole -
 
Base on our Fiennes expedition comms work Im still of an opinion that LF/MF  comms between stations inside the disturbed Auroral oval are typically actually way way better than on  the South side of it or in it during a Mag/proton event -   and often we sat there pondering - and came to the conclusion it was  like being in a one way semi conductor mirror or gold fish bowl with a very low noise level able to hear the world but the world not hearing us across the Oval . During the March 13th 1989 event another North Pole expedition hadn't been able to contact their Spitzbergen base and we were asked to look out for them at Ward Hunt on 2182kHz as part of the SAR - so I put out a few calls and there they were at S7  - them using 5W to a small wire and good earth - signals were so stable with nearly no fade at some 1400Kms in a twilight period and all within this goldfish bowl - I actually had to tell them to reduce power as their batteries were so dead they were FMing..
 
The other oddity was the excellent North  Pole to South Pole HF comms during the latter half of that event - we couldnt talk to Resolute or Eureka down the road, but could swap Met and Sitreps to South Georgia and Rothera bases at huge signals on what appeared chordal hop - what an oddity that was - once the iono recovered a bit we lost this path....
 
thanks for the input - roll out the "quiet sun" please.
 
Laurence KL7L
 
 

From: [email protected]
To: [email protected]
Date: Mon, 23 Mar 2015 18:42:00 +0000
Subject: LF: Re: Poor conditions

Hi Laurence and Roelof, Yes that was a big one on the 17th. I dont remember the Dst being depressed to -230nT for some quite long time. My thumbnail estimate says that it could take at least 14 days and possibly up to 21 days to really get back to to good conditions again. The succession of shocks really loaded up the ring current, and although the Dst has risen to -35nT its rate of increase has flattened out.
Because the CME "snow-ploughed" it way though a coronal hole high speed stream the event produced a large multiple proton event which has died away now, but the PCA effects tend to linger. We are still gettting shocks (Kp 6 yesterday and Kp=5 today) which may be "sub-storms". These occur when ions and electrons trapped in the mageto-tail are "spat back" towards Earth (another glob of plasma is spat in the opposite direction to conserve momentum) The mechanism is much like he release of energy from the strained Solar magnetic field that produced the CME. The trapped hot electrons "wind up" the field in the magneto-tail until it "snaps" into a lower energy state. The lost energy is carried by the ejected particles.
 
Alan
G3NYK 
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