Message-ID: <000001c39e44$0a7c7840$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "LF-Group" <rsgb_lf_group@blacksheep.org>
Date: Wed, 29 Oct 2003 17:10:54 -0000
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Subject: LF: Propagation after the storm
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Hi all, The solar conditions at present are as high as was seen during the
solar max a couple of years ago.

Night-time conditions were somewhat depressed even before the last geomag
storm. Also the day-time conditions had reached about 10dB of enhancement
over "normal" conditions, on the CT1DRP<>DCF39 path. It would seem that the
D-layer is now "saturated" with precipitated electrons, because despite the
high flux from the flare yesterday (X17.1) there was no noticable
improvement in signal levels corresponding to the flare timing. This
suggests that the arrival of the CME will not make conditions much worse at
night, and it is unlikely that daytime conditions will improve much above
those seen at present. CFH was seen for about an hours at lunch-time
(1200-1330z) but was still 15dB at least below normal nigt-time levels. This
suggests that although the ionisation level in the D-layer is sufficient to
reflect strongly rather than absorb, the height of the "reflecting layer" is
quite low (probably 50kms) thus requiring 4 or more hops for a transatlantic
passage. This may explain the lower levels observed.

Whilst the CME may not degrade propagation conditions further it will extend
the period before conditions return to a more normal state. I estimate it
could be 30 days or more before LF propagation returns to more normal
conditions for this part of the cycle. Joe VO1NA has shown that his signal
has been able to cross the pond under almost any conditions, but it will be
interesting to see if he can be detected in daytime........I suspect not
....CFH has a lot more power and is not usually that strong in daytime. I
could be wrong but it will be interesting to find out.

Cheers de Alan G3NYK
alan.melia@btinternet.com