Message-ID: <4F1E9D6E.30409@iup.uni-heidelberg.de>
Date: Tue, 24 Jan 2012 13:00:46 +0100
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: Very special condx over the pole?
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Hello Alan,

Thanks for your comments. Most probably you are right but you know i'm a=20
Dreamer and dreams can sometimes be unrealistic (not like transmissions=20
below 9 kHz ;-) ).
DCF39 is also transmitting all the time so probably Scott or those who=20
watch his DCF plot would already know about "magic" propagation.

Have a nice day.

73, Stefan

Am 24.01.2012 01:08, schrieb Alan Melia:
> Hi Stefan increases auroral activity leads to a big increase in noise a=
t
> high latitudes, what may be more difficult is that there has been a pro=
ton
> event which have was active from about Thursday last week and was just =
dying
> away yesterday. The M9 flare this morning produced a huge proton event =
one
> of the biggest I have seen for ages. These proton events are assocated =
with
> Polar Cap Absorbtion (PCA) and as Laurence knows (and bemoans) this wil=
l
> wipe out LF polar routes for some time.
>
> The auoral curtain is always there (somewhere) and it is possible we be=
lieve
> to bounce under it. So if the path is such that the ground reflection i=
s
> under the curtain rather than in the ionosphere, signals may get throug=
h.
> This means if you are inside the curtain then you need to be about 2000=
km
> from the opposite side for the signal to get out.
>
> The so called "large" geomagnetic event isnt that large (!) it was a Kp=
=3D5
> minor storm rating and only just. Most of the activity was Kp=3D4. The =
Dst was
> depressed to -55nT but the Ring Current was quite depleted anyway and t=
he
> Dst has already risen to -28nT (above -20nT is "good" )  This is a diff=
usion
> process so is exponential. I guess propagation tonight and tomorrow wil=
l be
> depressed but I think we then have to wait to see the effect of a CME t=
hat
> was associated with this morning's M9 flare this could be much bigger a=
nd my
> be more Earthward pointing. At present the Amination suggests again we =
will
> miss and direct hit and see a glancing blow from the shock front. This =
may
> give a major storm (Kp =3D6 or 7) which would depress LF propagation fo=
r a
> further week or 10 days.
>
> Not all activity is bad because very long very quiet periods lead to
> depressed signal levels too. I tend to think of this as an increased "l=
eak"
> from an under-ionised E-layer but I could be very wrong in my
> hypothesis.....no one has taken me to task on it yet so I keep sticking=
 my
> neck out :-))
>
> Alan G3NYK
> ----- Original Message -----
> From: "Stefan Sch=E4fer"<Stefan.Schaefer@iup.uni-heidelberg.de>
> To:<rsgb_lf_group@blacksheep.org>
> Sent: Monday, January 23, 2012 8:50 PM
> Subject: LF: Very special condx over the pole?
>
>
>   =20
>> Laurence, Alan, Scott, Jack, Steve, LF-experts... :-)
>>
>> Yesterday the K indes rised to above 5 so i think we hardly can expect
>> "usual" propagation over the pole to AK or VE7.
>>
>> My question is if there have ever been unusual propagation effects bee=
n
>> observed, during very strong geomagnectic activity. Things like Aurora
>> on VHF or a duct for LF?
>>
>> The pole and what happens there in the auroral oval is an interesting
>> imagination. I think (not being a propagation expert) it is always wor=
th
>> watching and transmitting.
>>
>>
>> 73, Stefan/DK7FC
>>
>>     =20
>   =20