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ARRL Propagation Bulletin ARLP010 (2023)

ARLP010 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 10  ARLP010
From Tad Cook, K7RA
Seattle, WA  March 10, 2023
To all radio amateurs 

ARLP010 Propagation de K7RA

So far this month, two new sunspot groups appeared on March 1,
another one on March 2, three more on March 3, one more on March 5,
two more on March 6, and another on March 7, then two more on March

Average daily sunspot numbers rose from 126.3 to 143.6.

Average daily solar flux changed from 158.2 to 181.6

Average daily planetary A index declined from 27.7 to 14.6, and
average middle latitude numbers went from 18.9 to 10.7, reflecting
the quieter conditions following the upset the week before.

The Penticton observatory, the source for solar flux data is way up
at 49.5 degrees north longitude, in eastern British Columbia. For
much of the year the Sun is low in the sky, so all winter they do
their thrice daily readings at 1800, 2000 and 2200 UTC. But on March
1 they shifted over to 1700, 2000 and 2300 UTC. The local noon (2000
UTC) reading is the official solar flux for the day.

You can see the data and the dates here:

The Vernal Equinox, when the northern and southern hemispheres are
bathed in equal solar radiation is less than two weeks away.

Predicted solar flux shows values peaking now, and again on March

Flux values are expected at 178, 175, and 170 March 10-12, 172 on
March 13-14, 170 on March 15-16, 180 on March 17-18, 175, 170 and
165 on March 19-21, 160 on March 22-23, 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, 175
on April 12, 180 on April 13-14, then 175, 170 and 165 on April

Predicted planetary A index is 8, 8, 10 and 8 on March 10-13, 5 on
March 14-15, 8 on March 16-17, then 5, 8 and 16 on March 18-20, 5 on
March 21-23, then 12, 16, 26, 18 and 10 on March 24-28, then 8, 24
and 16 on March 29-31, 20 on April 1-2, 16 and 8 on April 3-4, and 5
on April 5-10, then 16, 8, 8, 5, and 8 on April 11-15.

Dr. Tony Phillips of posted this animation captured
by NASA's SDO showing sunspot AR3245 splitting:

AR3245 is seen in the SE quadrant (lower left).

OK1HH wrote:

"The most interesting phenomenon in the last seven days was the X2
class solar flare in the AR3234 sunspot group. Flare peaked on 3
March at 1752 UTC, which caused the shortwave fade over the Americas
at frequencies up to 30 MHz.

"The G1-class geomagnetic disturbance on 4 and 5 March was triggered
by CMEs from the M8.6-class flare of 28 February, despite the fact
that the particle cloud was not heading directly toward Earth.

"Activity in the growing sunspot groups AR3242 and AR3245, as well
as the action of a setting, long, narrow, and closing coronal hole
in the northwestern solar disk, were key to the subsequent

"Today, March 9, a CME from the M5.8-class solar flare of March 6 at
0229 UTC appears to be arriving at Earth. This is evidenced by this
morning's (March 9) increase in solar wind particle concentration,
which is a fairly good precursor for a subsequent increase in solar
wind speed and enhancement in geomagnetic activity.

"After the disturbance subsides, quieter conditions and a
continuation of the current level of solar activity is expected."

Gene, N9TF in Tennessee wrote, concerning openings on March 8-9:

"I am usually the little pistol on the sidelines watching stations,
either on my waterfall, pskreporter, or DX Maps working the 6M DX.

"Well, the opening to VK4 yesterday late afternoon/evening, found
this station in the thick of things...FINALLY!

"I was tipped off by my brother N9PGG Greg in FM05 around 2200 UTC
in a text message, that he was receiving FK8HA on 6m FT8, and a
little later he saw stations in Alabama working VK4MA. I decoded
FK8HA a couple times around 2230 UTC on 3/8/2023 but only -20 and
just a couple sporadic decodes. I was watching DX maps and saw the
path from VK to grids just to the south of me on fire.

"I started CQing around 2230 UTC and saw that I was hitting XE2KK
with a +4 on pskreporter, and two other XE. That looked like a good
E opening to the correct path to VK4 if I had enough signal to ride
the TEP. (Was it TEP?)

"Finally, around 2342 UTC I decoded VK4MA at -13, and Paul was now
being decoded consistently here and getting stronger. I started
calling him at about 2345, and at 0007 UTC 3/9/2023 I got a reply
R-19, sent my RR73 and Paul moved on to the next caller. I thought I
was in the log...NOT!

"I noticed two callers after me, AB4IQ, Paul had finished with 73. I
immediately hit what I thought was TX4 (a text string in WSJT-x) to
send RRR this time but hit TX2 for a few transmissions until I
caught that mistake. Finally, 16 minutes of sending RRR, Paul
responded with 73. Relief and then satisfaction set in. I'm in the
log! Paul peaked at +1 for a while during the opening.

"Antenna is just a 3 element (A50-3S) only up 18' above ground,
behind our backyard shed 120' from the house/shack. I have 125' of
DXE400MAX buried from the house to the back of the shed to a coax
distribution box with grounding and surge arrestors. Then 40' of
LM4-400 from the box to the antenna. The rig is a K3S, and I run 85
watts output on FT8. So, of those 85 watts out at the rig, the
antenna is seeing about 45-50 watts, at only 18' above ground, it's
about 7' lower than the minimum optimal 25' above ground for 6m.

"The 6m antenna set up is temporarily permanent at this time. It is
kluged together with a 5' tripod anchored into the ground with 2,
24" nails in each leg. The mast is 4 sections of 4' army surplus
tent poles. I have an eve bracket at 10' to hold the whole thing
secure, snug but not completely tight so I can hand turn the mast
section above. Tent poles are just slid together, and the joints are
duct taped. Like I said...kluged together! It has just recently
survived 75mph straight wind gusts for 2 hours straight.

"Anyway, just wanted to give a 'successful' report from EM66IJ. It
was fun finally being able to participate in an opening!"

A british tabloid explains astrophysics:

Dr. Tamitha Skov, WX6SWW, releases videos to her Patreon subscribers
12 hours before the general release.

I got this early Friday at 0800 UTC, and since the ARRL will not
release this more than 12 hours after the release to her
subscribers, I am able to post it here:

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 2 through 8, 2023 were 103, 133, 122, 137,
173, 191, and 146, with a mean of 143.6. 10.7 cm flux was 168.8,
190.9, 181.6, 179.8, 188, 180.3, and 181.9, with a mean of 181.6.
Estimated planetary A indices were 9, 22, 15, 22, 15, 11, and 8,
with a mean of 14.6. Middle latitude A index was 8, 16, 10, 17, 11,
7, and 6, with a mean of 10.7.


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