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SB PROP @ ARL
$ARLP037
ARLP037
Propagation de
K7RA
ZCZC
AP37
QST
de W1AW
Propagation
Forecast
Bulletin 37
ARLP037
From
Tad Cook, K7RA
Seattle,
WA September
27, 2024
To
all radio
amateurs
SB
PROP ARL
ARLP037
ARLP037
Propagation de
K7RA
Seven
sunspot groups
emerged this
week. The
first was on
September 19,
three on
September 20,
one each on
September 22
and 23, and
the last on
September 25.
Average
daily sunspot
numbers
increased from
120 to 137.2,
and average
daily solar
flux shifted
from 175.7 to
164.3.
Geomagnetic
numbers were
much quieter.
Average daily
planetary A
index changed
from 35.7 to
14.3, and
middle
latitude A
index from
23.4 to 10.7.
Predicted
solar flux is
180 September
27 to October
1, 190 on
October 2-6,
185 on October
7-9, 180 on
October 10,
175 on October
11-16, 170 on
October 17-18,
165 on October
19, 160 on
October 20-23,
165 on October
24-26, then
170 and 175 on
October 27-28,
180 on October
29-30, and 190
on October 31
through
November 2.
Predicted
planetary A
index is 5 on
September
27-28, 8 on
September
29-30, 5 on
October 1-4,
10 on October
5-6, 5 on
October 7-9,
then 10, 20
and 19 on
October 10-12,
and 5 on
October 13-21,
8 on October
22-23, 5 on
October 24-31,
and 8 on
November 1-2.
"Weekly
Commentary on
the Sun, the
Magnetosphere,
and the
Earth's
Ionosphere -
September 26,
2024 from
OK1HH:
"Solar
flare activity
is generally
lower than it
was in the
first half of
September,
when M-class
solar flares
were common
and X-class
flares also
occurred. The
last
significant
M-class flare,
including a
CME, was
observed on
September 22.
However, the
Earth's
magnetic field
activity
increased on
September
25-26,
incidentally
in good
agreement with
the forecast.
"Propagation
conditions,
especially in
the shorter
half of the
shortwave
range, have
understandably
improved, but
not as much as
we might have
expected in
the run-up to
the equinox.
This was
influenced by
a decrease in
solar activity
(compared to
August levels)
- and of
course an
increase in
geomagnetic
activity.
"Unlike
in times
relatively
recently past,
any of us can
monitor not
only total
solar
activity, but
also changes
in solar wind
parameters.
Both its speed
and the
concentration
of free
electrons and
protons
ejected by
flares.
Changes in the
ionosphere
follow
quickly, but
not always in
the same way.
It is also
always the
result of
previous
developments."
Latest
report from
Dr. Tamitha
Skov, WX6SWW:
https://youtu.be/B9jWbAVEpZw
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.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 this QST
article:
https://bit.ly/3Rc8Njt
"Understanding
Solar Indices"
from September
2002 QST.
Instructions
for starting
or ending
email
subscriptions
to
ARRL bulletins
are at www.arrl.org/bulletins.
Sunspot
numbers for
September 19
through 25
2024 were 109,
113, 117, 114,
224, 123, and
160, with a
mean of 137.1.
10.7 cm flux
was 161.2,
153.8, 158,
162.8, 167.4,
172.4, and
174.2, with a
mean of 164.3.
Estimated
planetary A
indices were
20, 7, 6, 5,
13, 17, and
32, with a
mean of 14.3.
Middle
latitude A
Index was 15,
6, 6, 3, 9,
12, and 24,
with a mean of
10.7.
NNNN
/EX
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