Hi Jim, I can confirm your suspicions of a very much lower noise level on
136kHz over the last two nights. It is the first time I think I can remember
CFH being "washed out" by conditions when I knew it was active. My
night-time noise is about 8 to 10 dB lower than normal.
I think the CMEs have precipitated so many electrons into the D-layer that
it is permanently in a condition like normal daytime. No signals are getting
through to the E-layer at night. I have suggested previously that the noise
increase at night is due to the increase in distant noise conducted to the
receiver by skywave. Thus at present we have a "noise collection area" about
equal to normal daytime conditions. This skywave "noise collection"
explained the differences in noise profile between the western edge of
Europe and the eastern coast of the USA and Canada. Present conditions would
seem to confirm this idea.
Brian's plots of DCF39 show much enhanced daytime levels which are almost,
but not quite, equal to the lower night-time levels.
It will probably take around 30 days for these levels of ionisation to
decay, but the big sun-spots will rotate round and face Earth again in 27
days time, so, if they have any energy left, we could see quite a period of
the present disturbed conditions.
Plus point ....short (1000 to 2000kms) daytime (and possibly night-time)
contacts should be enhanced, so it is a chnace for the lower powered staions
to make contacts.
Cheers de Alan G3NYK
[email protected]
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