ARRL Propagation Report
SB PROP @ ARL $ARLP021
ARLP021 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 21 ARLP021
From Tad Cook, K7RA
Seattle, WA May 26, 2023
To all radio amateurs
SB PROP ARL ARLP021
ARLP021 Propagation de K7RA
Both average daily sunspot numbers and solar flux increased this
week. Average daily sunspot numbers rose from 118.6 to 133.4, while
average solar flux went from 143.2 to 161.2.
Geomagnetic indicators were more active. Average daily planetary A
index went from 9.6 to 17.1, while average middle latitude A index
rose from 9.6 to 14.4.
Predicted solar flux is 150 on May 26, 155 on May 27 and 28, then
150, 145, 140 and 135 on May 29 through June 1, 155 on June 2 to 4,
then 160, 165, 160, 155, and 150 on June 5 to 9, 145 on June 10 and
11, 150 on June 12, 155 on June 13 and 14, 160 on June 15, 165 on
June 16 and 17, then 160, 155 and 150 on June 18 to 20, 155 on June
21 and 22, then 160, 165 and 160 on June 23 to 25, 155 on June 26
and 27, 150 on June 28, and 155 on June 29 to July 1, then 160, 165
and 160 on July 2 to 4.
Predicted planetary A index is 15, 8, 5, 12 and 10 on May 26 to 30,
5 on May 31 through June 1, then 16, 8, 10 and 8 on June 2 to 5, 5
on June 6 to 15, then 12, 10, 5, 18, 22, 15 and 10 on June 16 to 22,
5 on June 23 to 28, then 16, 8, 10 and 8 on June 29 through July 2,
and 5 through the first week of July.
"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - May 25, 2023
We've seen another seven days of turbulent developments on the Sun
and around the Earth. The large, seen even without binoculars
(e.g., eclipse glasses) visible sunspot group AR3310 in the southern
hemisphere was the source of the strongest flare on May 16 with an
X-ray event maximum of M9.6.
Another group AR3311 in the north, due to its unstable magnetic
field configuration "beta-gamma-delta", produced almost all the
other flares. The stronger ones were the cause of Dellinger events
(SWF = Shortwave fadeout, in the case of M9.6 it was registered in
the whole shortwave range in the region where the Sun was high).
Moreover, the eruptions, combined with sporadic E layer, often
significantly affected the propagation in the lower shortwave bands
by deep and irregular fadeouts.
SOHO recorded a rare conjunction on May 21, when a filament near the
Sun's north pole was ejected as a CME in direction to the Pleiades,
Seven Sisters star cluster. Coronagraph on SOHO has been operating
since 1995 and was the first to operate in real time. No one had
ever seen anything like it before.
Since May 24, we observed a new and rapidly growing group of spots,
AR3315, in which we can expect more major solar flares as time goes
on. So the turbulent evolution with changing and often worsening
shortwave propagation conditions continues.
F. K. Janda, A.R.S. OK1HH"
"I have been in the DX hobby since 1950 and seem to see an
increasing, alarming recent trend in solar and geomagnetic activity
impacting trends in radio disturbances. Tell me I am wrong and it's
just a 'blip' but solar activity seems beyond the norm and
I replied that with greater solar activity we should expect more
flares, solar wind, and disturbances. I think the disturbances are
normal and expected with the rising solar cycle.
When I suspect conditions are disturbed, this is where I check to
see what is happening in real time:
Beautiful aurora: https://tinyurl.com/2zxdmpu6
Sunspot images: https://tinyurl.com/muaakxn9
Thanks to NO6ED for this story about an undersea volcano disrupting
the ionosphere. https://bit.ly/428OAwM
This weekend is the CQ World Wide WPX CW Contest.
Send your tips, reports, observations, questions and comments to
email@example.com. 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 at http://arrl.org/propagation-of-rf-signals . For an
explanation of numbers used in this bulletin, see
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/ .
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for May 18 through 24, 2023 were 121, 155, 138, 140,
97, 130, and 153, with a mean of 133.4. 10.7 cm flux was 150.6,
164.6, 169.6, 163.4, 161.5, 154.9, and 164.1, with a mean of 161.2.
Estimated planetary A indices were 3, 9, 35, 28, 21, 12, and 12,
with a mean of 17.1. Middle latitude A index was 8, 10, 26, 19, 17,
11, and 10, with a mean of 14.4.