XPost: rec.radio.shortwave, rec.radio.info

SB PROP @ ARL $ARLP032
ARLP032 Propagation de K7RA

ZCZC AP32
QST de W1AW
Propagation Forecast Bulletin 32 ARLP032

From Tad Cook, K7RA

Seattle, WA August 23, 2024
To all radio amateurs

SB PROP ARL ARLP032
ARLP032 Propagation de K7RA

Ten new sunspot groups appeared over this reporting week (August
15-21), but both solar flux and sunspot numbers were lower, due to
the extraordinary numbers in the previous week.

Average daily sunspot number declined from 255 to 180.3, while
average daily solar flux went from 284.9 to 232.7.

Geomagnetic numbers were quieter. Average daily planetary A index
declined from 28.6 to 11.9, and average daily middle latitude
numbers sank from 17.8 to 12.

On August 17 the planetary A index was 31, caused by a CME around
1400 UTC. A strong G3 geomagnetic storm was the result.

One new sunspot group appeared on August 15, and two more emerged on
every day from August 16 to 19, and one more on August 21.

Predicted solar flux is 230 and 235 on August 23-24, then 240 on
August 25-26, 230 on August 27, 235 on August 28-29, 205, 210 and
215 on August 30 through September 1, 220 on September 2-3, 225 on
September 4-6, 220 on September 7, 225 on September 9, 230 on
September 10-12, and 225 on September 13-16, 215 and 210 on
September 17-18, 200 on September 19-20, then 205, 210, 205 and 200
on September 21-24, and 205 on September 25-26.

The planetary A index prediction shows 8 on August 23, and 5 on
August 24 to September 17, 18 and 12 on September 18-19, then 5 on
September 20 through the first week in October.

I get mail asking why ten meters isn't open during all of the recent
high solar activity. The reason is the season. We have to be much
closer to the autumnal equinox to see ten meters open regularly.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere for August 22, 2024 from OK1HH.

"After the solar flare X1.1 on 14 August, accompanied by a CME, we
expected a geomagnetic storm. A more accurate prediction was
provided by the NASA model - the disturbance in agreement with it
started on 17 August around 1400 UT. The geomagnetic storm was
strong (G3), probably triggered by the arrival of more than one CME.

We observe two to three sunspot groups on the solar disk that can
produce moderate flares (they have a 'beta-gamma' magnetic field).
There are usually 10 - 12 groups in total. Coronal holes are few and
relatively small, which reduces the likelihood of an increase in
solar wind speed. Semi-regularly, days with higher MUF values (until
Aug 17, Aug 19 and Aug 21) alternated with decreases (Aug 14, Aug
18, Aug 20...), which could only be predicted to a very limited
extent and only for shorter intervals based on measured
interplanetary magnetic field variations. But these are mostly
impossible to predict."

Solar activity has remained at a 20-year high for most of this
summer, and so far there is no indication of a possible decline.

20 year record: https://bit.ly/3ACRphS [ https://bit.ly/3ACRphS ]

Kepler. Thanks to David Moore for this: https://cnn.it/3Xff40v [ https://cnn.it/3Xff40v ]


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 [ http://www.arrl.org/propagation ] and the ARRL Technical Information

Service web page at, http://arrl.org/propagation-of-rf-signals [ 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 [ http://arrl.org/the-sun-the-earth-the-ionosphere ] .


An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation [ http://arrl.org/w1aw-bulletins-archive-propagation ] .


More good information and tutorials on propagation are at
http://k9la.us/ [ http://k9la.us/ ] .

Also, check this. Understanding Solar Indices from September 2002
QST: https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ] .

Instructions for starting or ending email subscriptions to ARRL
bulletins are at http://arrl.org/bulletins [ http://arrl.org/bulletins ] .

Sunspot numbers for August 15 through 21 2024 were 164, 169, 170,
170, 213, 200, and 176, with a mean of 180.3. 10.7 cm flux was
227.4, 224.9, 229.5, 231, 239.1, 238.2, and 239, with a mean of
232.7. Estimated planetary A indices were 6, 8, 31, 13, 10, 7, and
8, with a mean of 11.9. Middle latitude A Index was 6, 11, 24, 15,
11, 9, and 8, with a mean of 12.
NNNN
/EX

ARRL The National Association for Amateur Radio®
Unsubscribe [ https://home.arrl.org/action/My-Account/Opt-In-Out ]

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)