Re: Propagation predictions?

[hermod@xxxxxx (Hermod Pedersen)]

This message is sent by hermod@xxxxxx (Hermod Pedersen)
to hard-core-dx@xxxxxxxxxxxxxxxx:

On Mon, 25 Mar 1996 13:59:50 +2000, you wrote:

>In the  PLAY DX  issue of 4-3-96 i have read that there were some 
>openings between  Europe and Bolivia and Peru and  was to predict that this 
>would be hapened again on 9-12 March 
>
>Is there a  'rule of tumb' for predictions of these cases ? or 10.7 cm flux and 
>A index are te only factors for making this predictions? 

A non-scientific rule of thumb would be like this:
Disturbed condition (=high A-indices) -> great reception of tropical
bands stations.
Calm conditions (=low A-indices) -> moderate to bad receptions on
tropical bands - but great on medium wave.

Normally one would think that disturbed conditions are bad for any
reception. One execpetion, though, is signals coming from tropical
station - and received in a northern (or southern) path. These signals
kind of slips under (below) the blackout of signals caused by the
higher flow of electrical particels, which is spreading out from the
polar regions.

Then there is a lot of variations:
Too disturbed conditions would block most signals.
Long periods of calm conditions is often bad for tropical band
reception, but favorable to reception in general, on both medium wave
and higher shortwave bands (especially during years of high solar
activity, when the flux flow "tightens" the reflective areas in the
jonosphere.

Though little study is made on disturbed condition<->tropical DX it is
a scientific accepted fact. As a DXer you can make good use of these
predictions, not having to listen to noise and nothing during periods
when you might be better of sleeping...
--
Redistribution of the material is not allowed without permission of
original poster or Kotanet Communications Ltd. Contributions to the
list are very welcome to hard-core-dx@xxxxxxxxxxxxxxxxx
For more information about hard-core-dx@xxxxxxxxxxxxxxxx email to
owner-hard-core-dx@xxxxxxxxxxxxxxxxx
--