07/25/2025
Solar activity was at low levels. The largest flare was a C7.6 from Region
4136. C-class activity was also observed from several other regions during the
highlight period. No Earth-directed CME activity was observed.
No proton events were observed at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit was at high levels
on 14-20 July in response to persistent positive polarity CH HSS influence.
Geomagnetic field activity reached Minor storm levels on 14, 15, and 17 July
due to positive polarity CH HSS influence. Solar wind speeds were elevated to
as high as 700 km/s on 15 and 17 July. The remaining days were at quiet to
active levels despite enhanced solar wind parameters.
Forecast of Solar and Geomagnetic Activity 21 July-16 August 2025
Solar activity is expected to be at mostly low levels with a chance for
M-class, Minor to Moderate, flares for the outlook period.
No proton events are expected at geosynchronous orbit.
The greater than 2 MeV electron flux at geosynchronous orbit is expected to be
at high levels on 21-22 July, 24-30 July, 5-6 August, and 10-16 August all due
to recurrent CH HSS influences. Low to moderate levels are expected on the
remaining days.
Geomagnetic field activity is expected to be at active to Minor storm levels on
23 July, 1-4 August and, 7-14 August due to recurrent CH HSS effects. Quiet to
unsettled levels are expected on the remaining days of the outlook period.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for
July 24, 2025 by F. K. Janda, OK1HH:
Less than a year has passed since the probable peak of the 25th eleven-year
cycle, which means that we are still in a period of high solar activity. This
does not necessarily mean that there must be a high sunspot number, many
eruptions, or a high level of solar radio noise power flux (or solar flux for
short). Currently, there is mainly the high speed of the solar wind that
alternately causes high concentrations of negatively charged free electrons in
the ionosphere, which quickly recombine with positively charged protons. The
result is irregular changes in shortwave propagation conditions, accentuated in
the summer by the activity of the sporadic E layer.
From mid-July, sunspot activity initially increased, then declined
significantly in the last third of the month as a result of the setting of
larger sunspot groups. No major eruptions were observed in the setting groups.
Therefore, the Earth's magnetic field calmed down, especially on July 20-21.
The geomagnetic disturbance on July 23 was expected, as the Earth entered the
co-rotating interaction region (CIR), where it was hit by solar wind and
triggered a G1-class geomagnetic storm (CIRs are transition zones between fast
and slow solar wind streams and contain shock waves and amplified magnetic
fields similar to those in CMEs).
Forecasts of further developments from various sources now differ considerably.
If we look at the part of the far side of the Sun that is currently hidden
behind the eastern limb of the solar disk, we can first expect the current
level of solar activity and, at the beginning of August, a slight decrease,
accompanied by a slight increase in geomagnetic activity.
The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found on YouTube
at:
https://www.youtube.com/watch?v=n1N58cOnedo[1]
The Predicted Planetary A Index for July 26 to August 1 is 5, 5, 5, 5, 5, 5,
and 15, with a mean of 6.4. Predicted Planetary K Index is 2, 2, 2, 2, 2, 2,
and 4, with a mean of 2.3. 10.7 centimeter flux is 135, 135, 130, 130, 130,
130, and 130, with a mean of 131.4.
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]
[1] https://www.youtube.com/watch?v=n1N58cOnedo
[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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