Hi again,
In response to my questions:
> Interesting that the actual sunspot count reported now
> is 330 sunspots. However, the SEC reports of the
> propagation "effective" sunspot count, which relates
> to the solar flux usually, is now "only" 75 spots for the
> last six hours, and only about 55 spots for the last 24
> hours! Also the reported flux is now 266 per Penticton
> Observatory, but the effective flux is only 123.....?
I have received a detailed reply directly from Jim Secan,
at the Northwest Research Assoc, Inc, the source of the
SSNef information. He has given permission for me to
share this with the group, from him:
" I'm the source of the effective SSN plots and data (since
the USAF stopped sharing theirs with the NOAA SEC). Your
point is a very good one, and one that's missed by people
running SSN-based ionosphere models for propagation
predictions. The current F10 (Penticton flux as measured
at 10 MHz) of over 250 will seriously overestimate the
amount of ionospheric plasma (as reflected in foF2) we are
currently seeing when plugged into almost any (if not all) of
these models. Throw in the fact that these models do not
work well at all during strong geomagnetic disturbances and
you've got a classic case of GIGO [garbage in...]
" The effective SSN value and the similar T-index calculated
by the Aussies are not perfect by any means. Using a single
global value to capture the departure of the observed
ionosphere from the climatological ionosphere
models underlying HF prop codes is bold, if not foolish.
These indices do provide, however, a good starting point -
a much better one than the observed SSN or F10. This is
particularly true when the observed F10 is so far away
from the long-term mean F10 (which is around 126, or
SSN=80, right now).
" So, between the storm and the fact that the ionosphere can
be "driven" by F10 only so far, your supposition that the
Penticton flux is "useless" for Prop estimates under current
conditions is right on the money.
"I want folks who might actually use this information to
understand what it is and what it isn't. A panacea it isn't, a
sometimes-useful guide it is. This SSNe work all came from
trying to use the old NTIA propagation prediction codes to
support USAF operations back in the mid-1970s. We found
that by twiddling the SSN until the model foF2
values were close to the observed values our prop predictions
were better.
Not perfect by any means, but better.
Jim Secan"
BTW, his work is also impacted by the potential budget
cuts of support of NOAA's Solar Environment Center and
all the reports produced each day.
The only band where signals from the US mainland can be
heard out here (Hawaii) just now is 17 meters.
73, Jim KH7M
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