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Message-ID: <005501cb0e75$075f7510$4001a8c0@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <AANLkTinPlqOiLpZLGeiyD44F17WyYrA3v33ZnWN8Sft3@mail.gmail.com>, <4C1A7966.9050001@gmx.com> <4C1A828D.31781.32C8A6F@dave.davesergeant.com> <4C1A8B31.4070706@gmx.com>
Date: Fri, 18 Jun 2010 00:04:56 +0100
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Subject: LF: Re: Re: Changing solar conditions
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Hi Mike
You have found that Kp and A are not good indicators of propagation
conditions at LF. Try looking at Dst instead. Dst effectively measures the
Equatorial Ring Current which is the electrons and ions trapped in the Van
Allen Belt from the last disturbance. Thus a big geomag storm will push Kp
up to 7 and be back to 1 in a couple of days but propagation can be
depressed for 2 weeks or more. My take on the reason for this is that the
Ring Current acts as a reservoir of hot electrons which are injected
(precipitated is the usual profesional term) into the ionosphere (and
diffuse down to the D-layer) at the sunrise edge. These hot electrons act
just like the daytime photodissociated electrons in daytime....they absorb
LF signals. The problem is they persist well into the night as well and the
level is topped up again next morning.

The Dst index gives a measure of the "pressure" or concentration gradient
driving electrons into the ionosphere. When it returns close to zero
conditions start to improve. There was a CME recently and a coronal hole
flow which have topped up the ring current. The Dst is running at
about -25nT conditions will be better when it returns nearer to -10nT. The
other thing at the moment is that the subtective signal to noise ratio will
be depressed by the levels of summer noise ....static.

After saying that all my observations have been on 136kHz and I have not
been able to do systematic 24/7 recordings of  "beacons" close to 500kHz but
I see no reason for it to be much different.

I use the plots from your Colorado University site
http://lasp.colorado.edu/space_weather/dsttemerin/dsttemerin.html
I think you might find these interesting......it took me a long time to
discover why the depressions lasted so long after a geomag storm had passed,
though it is well documented in professional literature by the likes of Jack
Belrose VE2CV....it was only with the satellite measurements that it started
to become clear.

Best Wishes
Alan G3NYK

----- Original Message ----- 
From: "Mike-WE0H" <we0h@gmx.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, June 17, 2010 9:53 PM
Subject: LF: Re: Changing solar conditions


> 17-Jun-2010 at 1806 UTC
> SFI = 72   A = 19   K = 2
> Conditions during the last 24 hours
> No space weather storms were observed for the past 24 hours.
> Forecast for the next 24 hours
> No space weather storms are expected for the next 24 hours.
>
> Solar Wind Data
> Provides solar wind velocity and energetic particle intensity
> Updated at: 2033Z on June 17, 2010
>   Velocity (km/s): 502.7
>   Density (protons/cm3): 2.7
>
> OK no storms but not normal solar conditions. This will cause issues
> with 600m as we have seen in the USA many nights. I am no solar expert
> but have watched the data and signals on 600m for a bit over a year now
> and noticed differences in propagation with the density figures
> elevated, velocity elevated, and A & K changes above normal values.
> Those figures do change rapidly as seen on this site:
> http://dx.qsl.net/propagation/propagation.html
>
> Mike
> WE0H
>
>
>
> Dave S wrote:
> > Where did you hear that? Currently the sun is very quiet, zero spots,
> > and the geomagnetic field 'unsettled' but certainly not storm. K index
> > currently 2. HF bands pretty dire, but due to lack of sunspots and
> > nothing to do with magnetic storms.
> >
> > 73 Dave G3YMC
> >
> > http://www.davesergeant.com
>