(C) ARRL Letter
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The K7RA Solar Update [1]
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Date: 2024-09
Eight new sunspot groups emerged over the past week.
Two appeared on August 30, three more on August 31, another two on
September 2 and one more on September 4.
Average daily sunspot number declined from 177.1 to 155.3, while
average daily solar flux barely changed from 229 to 230.3.
Spaceweather.com reported the average daily sunspot number for
August was 200, the highest monthly average in the past two decades.
Reader David Moore sent in this link about the same thing:
https://bit.ly/4cQHwdD
Predicted solar flux is 235 on September 6, 225 on September 7-8,
230 on September 9-13, then 250, 255 and 245 on September 14-16,
then 240, 235, 240, and 245 on September 17-20, 240 on September
21-22, 245 on September 23-24, then 240, 235, 230 and 225 on
September 25-28, then 230, 240, 245, and 250 on September 29 through
October 2, then 240 on October 3-4, and 245 on October 5-6, 240
again on October 7-10, then 250 and 255 on October 11-12.
Predicted planetary A index is 10 on September 6,and 5 on September
7, 10 on September 8-9, 8 on September 10-11, 5 on September 12-16,
8 on September 17-18, 5 on September 19-25, and 25 on September
26-27, then 15 and 8 on September 28-29, and 5 on September 30
through October 4, 10 on October 5, and 5 on October 6-13.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - September 5, 2024 from OK1HH:
"September 6th was the sixth day of a continuous influx of
solar-origin protons into the Earth's atmosphere. The likely source
is on the far side of the Sun, probably in AR3792, possibly AR3796.
This influx briefly intensified on 3 September at noon UTC.
"Overall solar activity remains high. The solar flux is again close
to the values measured on August 6-13, about 27 days ago, or during
the last solar revolution. Summer in the Earth's northern hemisphere
is slowly coming to an end and shortwave propagation conditions
should improve on average. This is happening, but at a slower and
more erratic pace. The reason for this is the irregular changes in
the activity of the Earth's magnetic field and the parameters of the
solar wind. Sometimes the changes are even opposite to what we would
expect - for example, on 4 September between 1000 to 1500 UTC there
was a rather significant and unexpected increase in geomagnetic
activity, without any major changes in MUF and overall propagation
conditions.
"We are now observing only a single small coronal hole on the Sun
now. It is located near the central meridian and there is no active
region nearby. Respectively, all three larger ARs, capable of
producing eruptions of moderate magnitude, are south of the solar
equator. Accordingly, we find no change in the short-term forecasts
from the current state. More optimistic are the medium-term
forecasts, which take into account seasonal changes."
The "Solar-Terrestrial Centre of Excellence" Newsletter:
https://www.stce.be/newsletter/pdf/2024/STCEnews20240905.pdf
Latest from Dr. Tamitha Skov, WX6SWW:
https://youtu.be/S07qt59PcWI
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
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at,
http://arrl.org/propagation-of-rf-signals . For
an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere .
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation . More good
information and tutorials on propagation are at
http://k9la.us/ .
Also, check this article:
https://bit.ly/3Rc8Njt "Understanding Solar Indices" from September
2002 QST.
Instructions for starting or ending email subscriptions to ARRL
bulletins are at
http://arrl.org/bulletins .
Sunspot numbers for August 29 through September 4 2024 were 124,
143, 180, 156, 200, 133, and 151, with a mean of 155.3. 10.7 cm flux
was 204, 214.2, 232.6, 231.6, 225.5, 242.1, and 261.8, with a mean
of 230.3. Estimated planetary A indices were 5, 23, 26, 16, 8, 7,
and 13, with a mean of 14. Middle latitude A Index was 5, 16, 19,
16, 7, 10, and 16, with a mean of 12.7.
[END]
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[1] Url:
https://www.arrl.org/news/the-k7ra-solar-update-844
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