|
SB PROP @ ARL
$ARLP047
ARLP047
Propagation de
K7RA
ZCZC
AP47
QST
de W1AW
Propagation
Forecast
Bulletin 47
ARLP047
From
Tad Cook, K7RA
Seattle,
WA December 6,
2024
To
all radio
amateurs
SB
PROP ARL
ARLP047
ARLP047
Propagation de
K7RA
Solar
activity seems
to have
dropped
dramatically
from a recent
peak. Are we
over the cycle
peak and
headed down
again? Too
early to say.
Daily
average
sunspot
numbers this
week sank to
120.1.
Predicted
solar flux is
175 on
December 6 to
8, 170 on
December 9 and
10, 175 on
December 11
and 12, and
205 on
December 13 to
17.
Predicted
planetary A
index is 8 on
December 6 and
7, 5 on
December 8 to
12, 10, 8 and
5 on December
13 to 15, 8 on
December 16 to
18, 12 and 8
on December 19
and 20 and 5
on December 21
through
January 6,
2025.
Commentary
from OK1HH:
"After
the unexpected
solar proton
flare of 21
November,
which took
place beyond
the Sun's
western limb,
a rain of
higher-energy
protons hit
the Earth's
atmosphere.
This solar
radiation
storm had a
greater impact
at higher
latitudes in
the southern
hemisphere,
where it
caused a
significant
increase in
attenuation.
"Two
days later,
two new large
sunspot groups
appeared near
the
southeastern
limb of the
Sun. These
produced
moderate
eruptions
daily, which
is more or
less normal
for the
11-year
maximum. These
are AR3905 and
AR3906, which
have grown
rapidly to a
size where
they can be
observed with
the naked eye.
There is a
relatively
small coronal
hole near them
that could be
influencing
the solar wind
enhancement.
"Following
the eruption
of a plasma
filament near
AR3901, a G2
class
geomagnetic
storm is
possible on
November 28
and 29, when a
CME is
expected to
impact.
However,
around 1900 UT
on November
28, when this
information is
written as
usual, nothing
is still
happening. We
will see what
happens next.
It is quite
possible that
the plasma
cloud will
only hit the
Earth a little
and it is also
not out of the
question that
it will miss
the Earth
completely. So
any prediction
at this point
has a low
probability of
coming true."
Send
your tips,
reports,
observations,
questions and
comments to [email protected].
When reporting
observations,
don't forget
to tell us
which mode you
were
operating.
For
more
information
concerning
shortwave
radio
propagation,
see www.arrl.org/propagation
and the ARRL
Technical
Information
Service web
page at, www.arrl.org/propagation-of-rf-signals.
For
an explanation
of numbers
used in this
bulletin, see
www.arrl.org/the-sun-the-earth-the-ionosphere.
An
archive of
past
propagation
bulletins is
at www.arrl.org/w1aw-bulletins-archive-propagation.
More good information and tutorials on propagation
are at http://k9la.us.
Also,
check
"Understanding
Solar Indices"
from September
2002 QST:
https://bit.ly/3Rc8Njt.
Instructions
for starting
or ending
email
subscriptions
to ARRL
bulletins are
at www.arrl.org/bulletins.
Sunspot
numbers for
November 28
through
December 4,
2024 were 149,
162, 103, 83,
113, 126, and
105, with a
mean of 120.1.
10.7 cm flux
was 213.9,
219.8, 204,
186.3, 185.3,
174.2, and
174.7, with a
mean of 202.2.
Estimated
planetary A
indices were
4, 8, 11, 7,
6, 13, and 7,
with a mean of
8.3. Middle
latitude A
Index was 3,
6, 9, 6, 6, 6,
10, and 5,
with a mean of
6.
NNNN
/EX
|
