SB PROP @ ARL $ARLP035
ARLP035 Propagation de K7RA
ZCZC AP35
QST de W1AW
Propagation Forecast Bulletin 35 ARLP035
From Tad Cook, K7RA
Seattle, WA September 13, 2024
To all radio amateurs
SB PROP ARL ARLP035
ARLP035 Propagation de K7RA
With sunspot numbers up and solar flux decreasing, we saw ten new sunspot
groups this week; two on September 6, three on September 7, two on September
8, one on September 9, and two on September 11.
Average daily sunspot numbers increased from 155.3 to 178.4, while average
daily solar flux declined from 230.3 to 223.7.
Geomagnetic indicators were quiet, with average daily planetary A index
dropping from 14 to 7.9 and middle latitude numbers from 12.7 to 11.7.
The solar flux forecast calls for 10.7 cm numbers at 210 on September 13-14,
205 on September 15-20, then 225 and 220 on September 21-22, then 225 on
September 23-24, then 230, 235, 230 and 225 on September 25-28, and 240 on
September 29-30, then 240, 245 and 230 on October 1-3, 220 on October 4-5,
225 on October 6-7, 220 on October 8-9, 225 on October 10-11, 220 and 215 on
October 12-13, 210 on October 14-15, then back up to 240 at the end of the
month.
Predicted planetary A index is 35 and 25 on September 13-14, then 15 on
September 15-16, then 12, 15, 12 and 12 on September 17-20, 5 on September
21-25, then 25, 25, 15 and 10 on September 26-29, then 5 on September 30
through October 4, 10 on October 5-6, then 30, 22 and 8 on October 7-9, 5 on
October 10-13, 8 on October 14-15, and 5 on October 16-22, then 25 on October
23-24.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere -
September 11, 2024 from OK1HH.
"The solar wind speed, as measured in geostationary orbit, increased in two
jumps on 12 September - first shortly after midnight UTC from 360 km/s to 430
km/s, then to 520 km/s after 0818 UTC. Meanwhile, the polarity of the
longitudinal (north-south) component of the IMF (Bz) was negative. The
consequence was a significant deterioration of shortwave propagation
conditions.
"The development continued on 12 September as the X1.3 solar flare was
detected at 0943 UTC. The source was a new AR turning into view off the
southeast limb (former AR 3792, whose high activity during the parade on the
Sun's far side was well known thanks to helioseismological observations).
"However, the strong (G3) Geomagnetic Storm followed, while threshold was
reached at 14:43 UTC. Values of critical frequencies f0F2 in the
mid-latitudes of the northern hemisphere of the earth were 2 MHz lower
compared to the previous days. Now it can be expected geomagnetic disturbance
around September 14 (possible arrival of particles from the September 11
CME). We may wait until September 18 for quiet days."
WP3GW wrote:
"After a 4 month hiatus, just began again on FT8. I have noted that the SFI
has been more than 200, and have worked European stations at about 2200 UTC,
three hours after propagation normally closes to the Caribbean.
"And have seen signals late night and in mornings before the Sun comes up in
10 meters, making it a twenty plus hours open band. Have made 7 new countries
on FT8 in almost 3 weeks.
"Hope these conditions keep good for this contest season.
"Cheers, Angel Santana WP3GW."
Jeff, N8II wrote:
"There have been somewhat limited openings to Europe on 10 meters for about 2
weeks. On Monday September 2 I worked several Southern EU and several UK
stations, some with good signals. Today, the 8th was exceptionally good. Not
only was the 10 meter band open to all but possibly NE Europe, but stations
in the Middle East were S9 to S9+20 dB. On SSB I worked A42K, Oman, and
4K6FO, Azerbaijan. Also, UA9CTT, Asiatic Russia was S9+20 dB and UN4L,
Kazakhstan was peaking S8 all of them working the All Asia Contest. I called
CQ with the majority of my callers from the UK all with good signals, many
over S9. The only somewhat weak Brit was a mobile running 5W who was peaking
S5. OH6TS, Finland answered my CQ, and I heard SM5CAK, Sweden over S9. I was
also called by Hungary and Romania. It was like the middle of October on a
good day, very surprising 2 weeks before the equinox. All of my QSOs were
between 1400-1520Z. I also worked JE6RFM on 15M SSB during that time and
heard a JA5 about S7. T
here was an Indonesian also on 15M working the Asian contest who was S9+.
"The Summer has been frustrating with very limited activity except in
contests above 20M. 20M was open through most of the night to Europe
throughout the June-August period.
"The sporadic-E was poor this year, fewer openings and mostly single hop.
Every day 10M was open to Central and South America. Around the middle of
August, we started getting daily openings to the West Coast. Since then, most
days were open to AF and OC. Hawaii has been loud on several occasions
including the NAQP Phone test 2nd weekend of August and was also briefly loud
during the Hawaii QP last weekend of August.
"Today September 12 there was a good F2 opening to EU; I worked two R4s (next
to Asia), several SP, DL, I, HB9, F. YL3BF called and was about S4-6. The UK
was not part of the opening. One of the Germans was running 15W to a 5M long
indoor wire and was peaking S9!"
The latest from Dr. Tamitha Skov, WX6SWW, Space Weather Woman:
https://youtu.be/RHphr4iloHs [
https://youtu.be/RHphr4iloHs ]
Impressive sunspots:
https://bit.ly/3zjgI8o [
https://bit.ly/3zjgI8o ]
Send your tips, reports, observations, questions and comments to
k7ra@arrl.net [ mailto:
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 September 5 through 11 2024 were 167, 188, 179, 176, 213,
147, and 179, with a mean of 178.4. 10.7 cm flux was 240.7, 248.9, 221.7,
227.6, 214.8, 205.2, and 207, with a mean of 223.7. Estimated planetary A
indices were 7, 8, 7, 9, 9, 7, and 8, with a mean of 7.9. Middle latitude A
Index was 8, 8, 9, 19, 9, 7, and 18, with a mean of 11.1.
NNNN
/EX
ARRL The National Association for Amateur Radio®
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ARLP035 Propagation de K7RA