08/29/2025
Solar activity was at low levels on 18, 20, and 21 August with only C-class
flares observed. Activity increased to moderate levels on 19 August following
an M1.1 flare at 19/0439 UTC from an area beyond the Eastern limb. Moderate
levels were also observed on 22 August as Region 4191 produced a long-duration
M1.7/Sf flare. Associated with this flare was a Type II radio sweep with an
estimated shock speed of 521 km/s. The associated CME was deemed to be behind
the Sun-Earth line.
Moderate levels continued into 23 and 24 August with an M1.9 and an M1.3 flare,
both originating from beyond the NE limb. While multiple CMEs were observed in
coronagraph imagery over the period, nearly all were at or beyond the Eastern
limb and none were considered to have an Earth-directed component.
Geomagnetic field activity was at quiet to unsettled levels on 18 and 24
August, bookending a negative polarity coronal hole high speed stream.
Unsettled to active conditions were observed on 20-23 August as CH HSS activity
elevated, with active to minor storm levels observed on 19 August.
Solar activity is expected to be at low levels, with varying chances for
M-class flares (Minor-Moderate events) through 20 September.
Geomagnetic field activity is expected to be at mostly quiet levels on 29
August-3 September and again on 11-14 September. Unsettled levels are likely
on 25-28 August, 7-10 September, and 17-20 September. Active conditions are
likely on 4-9 September and 15-16 September, with possible minor storming on
4-6 September and 15 September. All increased activity levels are associated
with coronal hole high speed stream influence.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for
August 28, 2025 by F. K. Janda, OK1HH:
Given the significant decline in solar activity this spring, I expected it to
increase by the end of summer at the earliest, and more likely by the beginning
of fall. This expectation is now beginning to be fulfilled. And if the rise
in solar activity continues, we can guess whether solar activity will continue
to grow until the possible second maximum of the 25th solar cycle, let's say
this fall.
A few days ago, sunspot groups began to appear in the eastern part of the solar
disk, which we knew about thanks to helioseismological observations. And not
only thanks to them, coronal plasma ejections extending beyond the eastern limb
of the solar disk were also observable, and in recent days, an increase in the
concentration of protons in the solar wind has also affected the Earth. The
conditions for shortwave propagation have improved significantly due to
increased solar radiation and have fluctuated significantly and rapidly,
especially during the occurrence of sporadic E layers. Active regions on the
Sun will pass through the central meridian in a few days. Their activity will
therefore begin to have a much greater impact on the Earth's magnetosphere and
ionosphere. More than a few surprises are expected.
The latest report from Dr. Tamitha Skov, WX6SWW, can be found at
https://www.youtube.com/watch?v=1mVzIvfHNtc[1] .
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation[2] and the ARRL Technical Information Service
web page at, http://arrl.org/propagation-of-rf-signals[3] . For an explanation
of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere[4] . Information and tutorials
on propagation can be found at, http://k9la.us/[5] .
Also, check "Understanding Solar Indices" from September 2002 QST.
https://bit.ly/3Rc8Njt[6]
The Predicted Planetary A Index for August 30 to September 5 is 5, 5, 5, 5, 5,
20, and 35, with a mean of 11.4. Predicted Planetary K Index is 2, 2, 2, 2, 2,
5, and 6, with a mean of 3.0. 10.7 centimeter flux is 158, 158, 155, 155, 145,
145, and 140, with a mean of 150.8.
[1] https://www.youtube.com/watch?v=1mVzIvfHNtc
[2] http://www.arrl.org/propagation
[3] http://arrl.org/propagation-of-rf-signals
[4] http://arrl.org/the-sun-the-earth-the-ionosphere
[5] http://k9la.us/
[6] https://bit.ly/3Rc8Njt
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