Message-ID: <4F5A1C82.9080608@iup.uni-heidelberg.de>
Date: Fri, 09 Mar 2012 16:06:42 +0100
From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Big solar flare - major geomagnetic storms to follow
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Hi Jay,

Yes, the sferic propagation on VLF is affected as well. I can see quite 
low noise background levels arround the dreamers band. This may even be 
an advantage for the VLF experiments since we can do it via the 
groundwave up to some 1000 km. :-)

73, Stefan/DK7FC

Am 09.03.2012 13:42, schrieb jrusgrove@comcast.net:
> Alan
>
> Thanks for the update and insight.
>
> Absolutely no trace of Stefan's signal in CT last night. A few nights 
> back he was 25+ dB s/n (in 28 mHz). Long distance VLF signal levels 
> below normal as well.
>
> Jay W1VD  WD2XNS  WE2XGR/2
>
>
> ----- Original Message ----- From: "ALAN MELIA" 
> <alan.melia@btinternet.com>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Friday, March 09, 2012 5:57 AM
> Subject: Re: LF: Big solar flare - major geomagnetic storms to follow
>
>
> Hi all more geomag storming this morning. It looks as though I might 
> have got my timing wrong. However the 56 hours to the Kp=7 event is a 
> bit slow for such a big event, and the predicted speed of that CME.
>
> I suspect this mornings event may be what I refered to yesterday as a 
> "sub-storm". This occurs when the plasma cloud sweeps past Earth and 
> some is then trapped in a "magnetic bottle" in the tail of the 
> magnetosphere. The magnetic field becomes highly distorted and twisted 
> by the extra hot charge. Just as in the Sun-spots this strain is 
> relieved as the field snaps back into a lower energy state. The excess 
> energy which is released as the field collapses is transfered to the 
> plasma "glob". The result is that two parts of the plasma are fired 
> off at very high speed. one towads Earth and one away from Earth (to 
> conserve momentum....a basic law of physics). This mornings event was 
> the shock of that plasma "bullet" arriving. I believe this mornings 
> event may have been of this nature.
>
> How does it affect LF? The charge from the "bullet" is injected into 
> the ring current so tops up the charge reservoir, and this lengthens 
> the period of excess attenuation in the night-time D-layer. There is 
> some discrepancy between the Dst estimates. The Colorado estimate is 
> running at about -50nT whilst the Kyoto value is around -150nT. Kyoto 
> is based on a number of ground located magnetometer observations and 
> is prone to rather wild fluctuations, and often "overshoots". The 
> Colorado plot is based on a calculation using the solar wind 
> parameters as observed by the ACE satellite. From my experience I find 
> the latter to be more useful/meaningful in terms of LF effects.
>
> Overall I think this indicates a mild effect. Long distance night-time 
> paths will be affected for a week or so. For a good indication of the 
> progress of of the recovery, watch the Dst as it returns to around 
> -20nT....the indication of quiet, good propagation conditions. Just 
> before the conditions settle there can be some exceptionally good 
> nights, probably caused by favourable fading/multipath. These are very 
> location dependent and do not work for everyone.
>
> However keep watching..... NOAA predict the possibility of more 
> X-Class flares from the current spots, with the associated CMEs.
>
> Good LF DXing !!
>
> Alan
> G3NYK
>
>
>