SB PROP @ ARL $ARLP010
ARLP010 Propagation de K7RA

ZCZC AP10
QST de W1AW
Propagation Forecast Bulletin 10 ARLP010

From Tad Cook, K7RA

Seattle, WA March 8, 2024
To all radio amateurs

SB PROP ARL ARLP010
ARLP010 Propagation de K7RA

Until March 6, new sunspot groups emerged daily over the past
reporting week, February 29 through March 6.

One new sunspot group appeared every day on February 29 through
March 3, then two new groups on March 4 and another on March 5.

It seems odd, but average daily sunspot number was about the same
(changing from 106.4 to 106.7), but the average daily solar flux had
a substantial drop, from 175 to 147.4.

Average daily planetary A index was up from 8.4 to 10, while middle
latitude numbers rose from 7.4 to 8.

The March 3 planetary A index was 29. Spaceweather.com reported a G2 geomagnetic storm at 0930 UTC. On March 7 they said NOAA expects a
minor storm on March 9.

The solar flux forecast sees a short term peak at 180 on March 21-23
and another on April 17-19.

Predicted solar flux is 140 on March 8-9, 145 on March 10-12, then
140 and 135 on March 13-14, then 170 on March 15-16, then 165, 160,
170 and 175 on March 17-20, 180 on March 21-23, 175 on March 24-25,
170 on March 26-27, 160 on March 28-29, then 165 and 145 on March
30-31, then 140 on April 1-2, 135 on April 3-8, and 140, 160, 170,
170, 165 and 160 on April 9-14.

Predicted planetary A index is 8 on March 8-10, 5 on March 11-23,
then 15, 12, 12, 5, 10, and 8 on March 24-29, and 5 on March 30
through April 5, then 12 and 10 on April 6-7, and 5 on April 8
through the middle of the month and beyond.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - March 7, 2024 from F.K. Janda, OK1HH:

"Active region AR3590 which swelled to the largest of the 25th solar
cycle in February and where the largest flare was observed, was
located on the northwestern limb of the disk in early March,
whereupon it was observed by the Mars rover Perseverance from Jezero
Crater (Jezero means Lake in Czech).

"From the solar flare on February 28, the CME arrived at Earth on
March 3 - one day later than predicted. It triggered a G3 class
geomagnetic disturbance, which began by developing a positive storm
phase with a significant increase in MUF. It continued over the next
three days in a negative phase with a significant decrease in MUF
and an increase in attenuation, especially in the polar regions.

"Neither major flares nor major geomagnetic activity are expected in
the next few days. Therefore, propagation will gradually improve to
slightly above average. We expect a significant improvement around
the equinox. This time, however, the improvement will be more
pronounced as solar activity will gradually increase in the
meantime."

The Vernal Equinox occurs at 0306 UTC, March 20 and marks the
beginning of Spring in the Northern Hemisphere and the Autumnal
Equinox in the Southern Hemisphere.

Max Planck Institute for Solar System Research is looking for
volunteers:

https://bit.ly/4a43yZk

From DailyMotion, an August 2022 solar video:

https://bit.ly/3v0RARw

Space.com article about the April 8 solar eclipse:

https://bit.ly/3PdXnKl

Eclipse missions:

https://stardate.org/podcast/2024-03-07

An article about solar dynamo behavior during a Grand Solar Minima:

https://www.nature.com/articles/s41598-024-55317-w

From LiveScience, is the peak of Solar Cycle 25 already here?

https://bit.ly/3Taxe0p

A quiet Sun:

https://bit.ly/3T98PIh

Thanks to W7WKR for this article about Maritime Radio Historical
Society Station KPH:

https://bit.ly/49Fpjiz

[Station K6KPH also transmits W1AW Qualifying Run transmissions: https://www.radiomarine.org/mrhs-stations/blog-post-title-four-r3jyw
-Ed.]

Send your tips, reports, observations, questions, and comments to k7ra@arrl.net. 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 QST article about Solar Indices:

https://bit.ly/3Rc8Njt

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .

Sunspot numbers for February 29 through March 6 2024 were 107, 120,
91, 90, 113, 121, and 105, with a mean of 106.7. 10.7 cm flux was
164.1, 152.8, 152.3, 145.5, 139.9, 141.5, and 136, with a mean of
147.4. Estimated planetary A indices were 4, 9, 5, 29, 10, 7, and 6,
with a mean of 10. Middle latitude A index was 4, 9, 3, 20, 8, 7,
and 5, with a mean of 8.
NNNN
/EX


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* Origin: American Radio Relay League (3:633/280.2@fidonet)