ARRL

Register Account

Login Help

News

The ARRL Solar Report

03/07/2025

Spaceweather.com is reporting "A Hole In The Sun's Atmosphere" that
should reach Earth on March 9 and 10.

Solar activity has been at moderate levels for the past 24 hours.
The largest solar event of the period was a M1 event observed on
March 5 at 1150z from Region 4016. There are currently 10 numbered
sunspot regions on the disk.

Solar activity is expected to be low with a chance for M-class
flares and a slight chance for an X-class flare on March 7 and 8.

There is a chance for isolated minor solar radiation storm levels
throughout the period if any of the returning/developing
magnetically complex regions are active and produce an event.

Geomagnetic field activity is expected to be at quiet to unsettled
levels on March 7 to 9, 19 to 24, and on March 29.  Active levels
are expected on March 10 to 18, and then on March 25 to 28, with
possible G1 (Minor geomagnetic storm) conditions on March 12 to 15
associated with recurrent negative polarity Coronal Hole influences.

Quiet to unsettled conditions are expected on as weak, glancing CME
effects continue to wane with quiet conditions prevailing on March
7.  Unsettled to active levels are expected on March 8 as CIR - a
CIR is a Corotating Interaction Region, its primary effect creates
disturbances in the solar wind by interacting between fast and slow
streams of solar plasma - effects ahead of a recurrent, negative
polarity Coronal Hole become geoeffective.

The NOAA Space Weather Prediction Center with its Geomagnetic
Activity forecast for March 7 to 9 has a 40% chance of Active
activity on March 8, a 40% chance of a Minor storm on March 9, a 15%
chance of a Moderate storm on March 9, and a 1% chance of a
Strong/Extreme storm during this same reporting period.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - March 6, 2025, by F. K. Janda, OK1HH:

"The combination of relatively low total solar activity and a larger
number of geomagnetic disturbances caused a worsening of shortwave
propagation conditions in February. However, the outlook for March
is better, not least because of the approaching equinox (which
occurs on 20 March).

"Solar activity will begin to increase more rapidly after the larger
sunspot groups return to the Sun's disk (which is the half of the
Sun's surface visible from Earth). At its eastern limb we should see
their activity as early as mid-March. They will approach the centre
of the disk just around the Vernal Equinox on March 20.

"But even before that, the scenario may be somewhat different. In
the north-west of the solar disk, we see a large coronal hole, which
is likely to be the source of a strong solar wind that will probably
affect the Earth's ionosphere sooner than we expect. But this too
could be a harbinger of a further upsurge in solar activity. So -
within reason - all good news."

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 . Information and
tutorials on propagation can be found at, http://k9la.us/ .

Also, check this:

https://bit.ly/3Rc8Njt

"Understanding Solar Indices" from September 2002 QST.

The forecast 10.7 centimeter flux for March 7 to 13 is 150, 150,
150, 155, 160, 170, and 180, with a mean of 59.3.  The forecasted
Planetary A Index for March 7 to 13 is 5, 5, 8, 15, 15, 25, and 30,
with a mean of 14.7.  The forecast Planetary K Index for March 7 to
13 is 2, 2, 3, 4, 4, 5, and 5, with a mean of 3.6.
 



Back

EXPLORE ARRL

Instragram     Facebook     Twitter     YouTube     LinkedIn