Södertörns Radioamatörer

SB PROP @ ARL $ARLP005
ARLP005 Propagation de K7RA

ZCZC AP05
QST de W1AW  
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7RA
Seattle, WA  February 2, 2024
To all radio amateurs 

SB PROP ARL ARLP005
ARLP005 Propagation de K7RA

"ASWFC GEOMAGNETIC DISTURBANCE WARNING ISSUED AT 0248 UTC/02
FEBRUARY 2024 BY THE AUSTRALIAN SPACE WEATHER FORECASTING CENTRE.

"A CME was observed from 01/0800 UT. This CME is expected to pass
mostly above the Earth, however a glancing blow is possible either
late UT day 03-Feb or early UT day 04-Feb to cause possible G1-G2
geomagnetic storming. A coronal hole wind stream may also contribute
to enhanced geomagnetic activity.

"INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL MASS
EJECTION FROM 04-05 FEBRUARY 2024."

Seven new sunspot groups emerged this reporting week, but solar
activity was lower. One new spot appeared on January 26, two more on
January 28, three more on January 30 and one more on January 31.

Then on February 1 five new sunspot groups emerged, and the daily
sunspot number rose to 113, far above the average for the previous
seven days.

Average daily sunspot number dropped from 130.6 to 71.6, and average
daily solar flux declined from 173.3 to 145.4.

Average planetary A index changed from 7.4 to 6.9, while middle
latitude averages shifted from 5.1 to 5.6.

What is the outlook for the next month? Looks like a modest peak in
solar flux at 175 on February 20.

Predicted solar flux is 135 on February 2, 140 on February 3-5, 145
on February 6-8, then a jump to 165 on February 9-11, 170 on
February 12, 165 on February 13-15, 170 on February 16-19, 175 on
February 20, then 170, 165, 160, 150, 140, 135 and 140 on February
21-27, 145 on February 28-29, and 150 on March 1-2, then 155 on
March 3-4, 160 on March 5, and 165 on March 6-9.

Predicted planetary A index is 5 on February 2-3, then 14, 20 and 8
on February 4-6, then 5 on February 7-16, 8 on February 17-18, 5 on
February 19-24, then 10, 12 and 10 on February 25-27, and 5 on
February 28 through March 2, then 10 on March 3-4, and 5 on March 5
through the middle of the month.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - February 1, 2024, from OK1HH:

"A week ago, it appeared that more activity would come from the
large sunspot group AR3561, but it has been quiet. Then another
larger one, AR3559, surprised us when energetic protons began to
penetrate the Earth's atmosphere in the early hours of January 29
UTC.

"Such an event is called a 'radiation storm,' denoted by the letter
S, and this one was classified as S2. The letter R denotes the
effects of solar X-ray and ultraviolet radiation, which in this case
was caused by a fairly massive M6.8 class solar flare. The Dellinger
effect with a maximum at 0632 UTC affected frequencies up to 30 MHz
in the region of Western Australia and the adjacent Indian Ocean.
Protons with an energy of 100 MeV hit the Earth's atmosphere for
almost the entire day on 29 January, and protons with lower energies
continued to hit on the following days.

"Only isolated, weaker C-class flares were observed in the following
days. However, the Earth was not affected by the CME; its magnetic
field remained calm to slightly unsettled, and so shortwave
propagation conditions were generally between average to slightly
above average.  However, the increased solar radiation caused
regular daily openings of the upper shortwave bands, including the
10-meter band."

UC Berkeley article on Sunspots:

https://bit.ly/48ThdlY

Two articles on a Solar Cycle peak this year:

https://bit.ly/48Yjcpa

https://bit.ly/3u53ZDK

Two articles about the Sun's poles reversing:

https://bit.ly/4bvvmro

https://bit.ly/42kfljC

"Times Now" article about Radio Blackout:

https://bit.ly/3HGWYfn

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 January 25 through 31 2024 were 101, 97, 52, 75,
48, 53, and 75, with a mean of 71.8. 10.7 cm flux was 160.5, 156.7,
148.1, 141.1, 140.3, 135, and 136.2, with a mean of 145.4. Estimated
planetary A indices were 6, 6, 5, 8, 9, 8, and 6, with a mean of
6.9. Middle latitude A index was 4, 4, 4, 5, 7, 8, and 7, with a
mean of 5.6.
NNNN
/EX