Hi all, for those of you that are interested in propagation, sunspots, solar
X-ray flares and aurora (not to mention Coronal holes and CMEs ) there is an
interesting article in the April 2001 issue of the Scientific American
Journal. It does not have anything to say about disruption to radio
propagation but it does have a lot of 'new' information about CMEs and the
production of the shock-front.
(It may be available on their web site, I haven't looked)
It describes the injection and ejection of particles from the
'plasma-sphere' by the collision with the magnetic field of the CME. ( I
think the 'plasma-sphere' they refer to is what is often called the Van
Allen belts.) I believe this 'dynamo' effect could also inject energetic
particles into the ionosphere, at the poles. These would be much 'hotter'
than photo-dissociated ions, and so would take quite a long time to
recombine (decay)....maybe as much as 10 days.
The most interesting thing for me is that it 'decouples' the CME events from
the X-ray flares. The older references were not able to do this not having
access to data from the Geos and SOHO satellites. CMEs it seems can be
caused by the same mechanism that releases an X-ray flare, but they can
occur by other means without the release of X-rays. This accounts for some
'bad nights' on the CFH plots that did not seem to correlate with previous
flares.
SXV seems to be showing some signs of the effects of the recent CMEs as it
has become very weak in daytime today.
If the D-layer is heavily ionised by now it will be interesting to see if
there is enhanced range from some of the weaker eastern European stations
this weekend, due to daytime 'skywave'.
Cheers de Alan G3NYK JO02PB
[email protected]
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