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The ARRL Solar Report

02/21/2025

Solar activity is expected to range from low to moderate levels
through March 15.  There is a varying chance for R1 or R2 (Minor or
Moderate) events, and a slight chance for R3 or greater events.

Geomagnetic field activity is likely to reach G1 (Minor) levels on
February 28, March 9, and March 12 to 14.  Active levels are
predicted for March 1. Quiet, and quiet to unsettled conditions are
expected to prevail throughout the remainder of the period.

The NOAA Ap Index Forecast is 5 for February 21 and 22.

The NOAA Space Weather Prediction Center reports no space weather
storms predicted for the next 24 hours.

For the last 24 hours, solar flare activity has been at low levels
with only a C-Class observed.  The largest flare was a C8.1 on
February 19.

This flare was accompanied by a Type II radio emission and
associated CME off the Southwest edge of the solar disk. Modelling
efforts determined the bulk of the CME to miss ahead of Earth's
orbit.  However, a weak glancing influence cannot be ruled out late
on February 24.
 
Region AR3996 is the largest and most complex region on the disk but
was responsible for only one C-Class flare. Flux emergence and an
increase in interior spots can be seen in Region AR3998 but overall
the region has been fairly quiet.

Spaceweather.com has an article link from the "Advancing Earth And
Space Sciences" website concerning an extreme compression of Earth's
magnetic field that was caused by the May 2024 solar superstorm.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - February 20, 2025, by F. K. Janda, OK1HH:

"The increase in geomagnetic activity following the decrease in
solar activity is a simple phenomenon to explain: systems of
magnetic field lines over active regions in the Sun open up and
charged particles (both free electrons and the nuclei of hydrogen
atoms, or protons themselves) slip through them more easily into
space.

"In Earth's orbit, we see an increase in the solar wind and,
consequently, an increase in geomagnetic activity. At the same time,
the ionization rate of the ionosphere is increasing, while the
shortwave propagation conditions may not only worsen (due to
scattering on inhomogeneities) but also improve as the MUF may grow.
This was well known, for example, on Saturday 15 February on the
Europe-North America route.

"The only geomagnetically quiet days in the first half of the month
were 3-7 February. Then the solar wind, blowing from the long
canyon-shaped coronal hole, intensified and geomagnetic activity was
elevated for most of the second third of February. A calm trend can
be expected on most days of the last third of the month. Although
there does not appear to be a significant increase in solar
activity, it is sufficiently high. In addition, spring is
approaching, which is good news for the state of the ionosphere."

The predicted Planetary A Index is 5 for February 21 to 26, and 10
on February 27.  The predicted Planetary K Index is 2 on February 22
to 26, and 3 on February 27.  Predicted 10.7 cm solar flux is 170
for February 22 to 23, 190 on February 24, 195 on February 25, 200
on February 26, and 195 on February 27.

Sunspot numbers for February 16 to 20, 2025 were 271, 218, 187, 119,
and 123, with a mean of 183.6.

 



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