Register Account

Login Help

ARRL Propagation Bulletin ARLP011 (2023)

ARLP011 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 11  ARLP011
From Tad Cook, K7RA
Seattle, WA  March 17, 2023
To all radio amateurs 

ARLP011 Propagation de K7RA

Six new sunspot groups emerged over the past week, two on March 9,
another on March 10, one more on March 12, and another two on March

Sunspot numbers and solar flux declined this week.

Average daily sunspot numbers softened from 143.6 to 118.7, and
average daily solar flux from 181.6 to 153.6.

Predicted solar flux is 135, 140, 138, and 135 on March 17-20, then
132, 132 and 130 on March 21-23, 155 on March 24-26, 150 on March
27-28, 145 on March 29-30, then 140, 145, 150, 155, and 160 on March
31 through April 4, 165 on April 5-8, 170 on April 9-11, then 175,
180, 180, 175, 170 and 165 on April 12-17, 160 on April 18-19, 155
on April 20-21, then 140, 150, 150 and 145 on April 22-25.

Predicted planetary A index is 8, 5, 5, 12 and 8 on March 17-21,
then 5, 5, 12, 16 and 26 on March 22-26, then 18, 10, 8, 24 and 22
on March 27-31, then 16 on April 1-2, then 14, 12, 8 and 10 on April
3-6, 8 on April 7-8, then 5, 8, 22 and 8 on April 9-12, 5 on April
13-14, then 8 and 16 on April 15-16, 5 on April 17-19, then 12, 16,
26 and 18 on April 20-23.

Check out this propagation modeling site, sent from WB6MPH.

Jon, N0JK wrote:

"On March 15 there was a CME impact. The Kp peaked at 6. 6 meters
opened to South America. I logged HK3O in FJ24 at 2042 UTC on FT8.
Decoded many stations in Argentina and Ecuador."

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - March 16, 2023 from OK1HH, F.K. Janda.

"The level of solar activity is only slightly lower than during the
last solar rotation, but this is especially true below the Sun's
equator. There is higher activity on the far side of the Sun.

"There was exceptional phenomenon recorded by coronagraphs on
satellites on March 13. It was a 'halo CME' that apparently left the
Sun at more than 3,000 km/s. Although the plasma cloud was not
heading towards Earth, it still touched it. We can't pinpoint its
source, but helioseismic maps show a pair of large active regions on
the far side of the Sun. Both will emerge within days on the eastern
limb of the solar disk.

"The greater than 10 MeV proton flux was recorded from the morning
of the 13th and ended on the 15th. In the next two days, the CME
impact triggered a geomagnetic storm at G1 and G2 levels. In doing
so, the attenuation in the polar cap - PCA - increased

"Geomagnetic observatories recorded a high K index value of 6 on 15
March at 2322 UTC. Note: this CME was ejected into space by the
eruption of a magnetic filament on the Sun almost 4 days earlier.

"Shortwave propagation conditions were above average until 14 March
and deteriorated significantly on 15 March. However, due to
sufficiently high solar activity there was an improvement from 16
March onwards."

KM0T wrote:

"Finally got VP8 on 6M - Wednesday March 15.

"Been getting at least one and maybe two decodes from VP8NO and
VP8LP almost every day over the last week, but not enough to work,
seems always east coast, SE and Texas, some 6 land.

"Today, waiting in the wings, decoded a VP8 around 1700 UTC, kept
the beam that way and VP8LP came in at 1856 with -04 sigs.  I got a
-20 report. I missed his initial CQ at 1854 which was +18!  He
dropped down to -15 right after I worked him and then was gone. He
was in from 1854 to 1858, 4-minute window. Then one more single
decode him calling CQ at 1900 at -10, then gone.

"Anyway, it was short lived, then a few minutes later at 1909 UTC
VP8NO came in with +4 to -10 sigs till about 1918 UTC. I apparently
got his attention as Greg, W0LGQ in Council Bluffs EN21, south of me
told me on the phone that VP8NO was calling me back with a -12
report for a number of sequences, but I was getting no decodes by
then from him.

"Greg indicated as we compared notes, that WSJT FT8 signal reports
from VP8NO were consistently +10 dB better at EN21 then EN13 - 167
miles as the crow flies.  We both run 6 over 6 so it's somewhat a
good comparison.

"Definitely short lived F2.  From here, seems that TEP always ends
up dropping off mid country LU or CE, CX.  Never that far south to

"Well, now that I look at the DX Maps snapshot, it appears there may
have been an Es to TEP link on my side."

Tony, WA4JQS sent a message about working some New Zealand stations
on 29.6 MHz FM.

"Rich, N8UX and I have talked about this ever since FT8 came out. We
are seeing a lot of skewed path QSOs over the past few years. Today
the SFI was 157. I am thinking we have some prop paths or types we
did not know about until FT8. Of course, I could be wrong, but I
have seen some really strange paths the past few years with FT8. I
listened for 10 mins after I signed with the ZL2, and I was the only
one to hear and work him other than the VK3 and they were having
trouble getting the calls correct. While I had a pipeline, into the
South Island but then I find it strange that I heard no other VK or

WB6MPH sent this very interesting link, providing an animated visual
rendering of predicted propagation:

He also is interested in possible effects of planetary positions on
the Sun. Years ago I heard about J.H. Nelson of RCA and his work on
this subject, but thought that this article showed his conclusions
were affected by statistical artifacts, as outlined here:

Greg Glenn sent this:

"Check out Frank Stefani's work.  He is one of many who I read up
on. Stefani was a peer reviewer on my paper.


"Recent Stefani technical paper:


"Basically, Stefani suggests that even a very small gravitational
force exerted by the planets on the Sun can have an effect through
billions of years of resonance.

"I personally think that both gravitational, as well as
electromagnetic forces are at play.  It's a solar 'system' and there
are multiple forces transferred between the orbiting planets and the

"I write, along with Astronomer Gerald Pease, about the
gravitational force exerted by transfer of angular momentum here:


"I then wrote about the possible Electromagnetic Connections here:


"A prediction I made that came about:


"Thanks, Greg!"

Latest from Dr. Tamitha Skov, WX6SWW:

Solar explosions:

From news in India:

Send your tips, reports, observations, questions and comments to When reporting observations, don't forget to
tell us which mode you were operating.

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service at . For an
explanation of numbers used in this bulletin, see .

An archive of past propagation bulletins is at . More good
information and tutorials on propagation are at .

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for March 9 through 15, 2023 were 155, 135, 126,
135, 87, 97, and 96, with a mean of 118.7. 10.7 cm flux was 178.8,
171.2, 157.4, 150, 143.3, 138.5, and 135.7, with a mean of 153.6.
Estimated planetary A indices were 17, 11, 7, 8, 3, 17, and 29, with
a mean of 13.1. Middle latitude A index was 14, 10, 5, 6, 2, 12, and
19, with a mean of 9.9.


Instragram     Facebook     Twitter     YouTube     LinkedIn