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ARRL Propagation Bulletin ARLP009 (2023)

ARLP009 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 9  ARLP009
From Tad Cook, K7RA
Seattle, WA  March 3, 2023
To all radio amateurs 

ARLP009 Propagation de K7RA

This was a busy week for geomagnetic storms. A solar wind stream
from an equatorial hole and a CME blew geomagnetic numbers seemingly
off the scale, with the planetary A index on Monday hitting 94.
Aurora was visible as far south as 40 degrees latitude. Imagine a
line running from Reno, Nevada through Provo, Utah then Denver, then
the Kansas-Nebraska state line, Quincy, Illinois, Dayton, Ohio and

This week the source of the 10.7 cm solar flux, the DRAO observatory
at Penticton, British Columbia, was again saturated by solar wind on
February 25 and the measurement was 279.3. NOAA corrected this to
152, which I thought was a bit too low. The other recent saturation
was on February 17 at 343.1, but for some reason NOAA let this

I corrected it in this bulletin to 165, which was that morning's
1800 UTC reading:

This week we saw two new sunspot groups appear on February 23,
another on the following day, another on February 27, on February 28
one more, two more on March 1, and another on March 2.

Average daily sunspot number rose from 107 to 126.3, but average
daily solar flux declined from 162.4 to 158.2.

Average daily planetary A index rose from 10.6 to 27.7.

Over the next few weeks it appears that solar flux values should hit
a peak around March 17-18.

Predicted solar flux is 165 March 3-5, 170 and 175 on March 6-7, 180
on March 8-9, 165 on March 10-12, 170 on March 13-15, 175 on March
16, 180 on March 17-18, then 175, 170 and 165 on March 19-21, 160 on
March 22-23, 155 on March 24-26, 150 on March 27-28, then 145 on
March 29-30, then 140, 145, 150, 155 and 160 on March 31 through
April 4, then 165 on April 5-8, and 170 on April 9-11.

Predicted planetary A index is 5, 12, 20, 18, 16 and 8 on March 3-8,
5 on March 9-14, then 15, 8, 8, 5, 8 and 15 on March 15-20, 5 on
March 21-23, then 12, 16, 56, 32, 16 and 10 on March 24-29, 8 on
March 30-31, then 16, 18, 15 and 8 on April 1-4, and 5 on April

Note the predicted A index of 56 and 32 on March 26-27, suggest a
return of this week's disturbance in the next solar rotation.

Here is a Newsweek report about radio blackout:

A story from Sky & Telescope:

Click past all the offers and pop-ups to view this article:

That report is from Western Washington, where I live. Unfortunately
the sky was overcast, but observers in Eastern Washington were able
to see the aurora. Remember that many of the aurora images you see
were from cameras with a long exposure time, which makes them much
brighter than what you see with unassisted vision.

Thanks to for this NASA movie of sunspot group
AR3234 growing as it comes over our Sun's eastern limb: also reported that the average sunspot number for
February was among the highest of the last 10 years.

Here is data on Solar Cycle 25 progress:

Geomagnetic activity forecast for the period March 3-9, 2023:

"Quiet: March 3-5, 9
Unsettled: March 4-6, 8-9
Active: March 6-7
Minor storm: possible March 6-7

"At February 27, we recorded the highest geomagnetic activity since
2008. At Budkov observatory, the three last K indices of this day
were at level 6. Over the next few days we expect geomagnetic
activity decrease. Until Sunday, March 5, we expect mostly quiet
conditions. More unsettled conditions are expected between Sunday,
March 5, and Thursday, March 9.

"Between March 6-7, active conditions with likely storming event is
possible. Wednesday, March 7, we expect unsettled conditions.

"Tomas Bayer, Institute of Geophysics of the ASCR, Prague, Budkov
observatory (BDV)."

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere March 3-9, 2023 from F.K. Janda, OK1HH:

"A week ago, we observed an increase in the size and flare activity
of sunspot group AR3234 in the northeast of the solar disk. But more
interesting was the activity in the northwestern quadrant, where a
magnetic filament associated with the relatively little noticeable
sunspot AR3229 erupted on February 24. It set off a chain reaction
in which the filament lifted off and cut through the solar
atmosphere at 1949 UTC.

"In AR3229 a long-duration M3-class solar flare (LDE) at 2030 UTC,
with a CME, partially directed toward Earth. At the same time,
gaseous material flowed from an equatorial coronal hole in the solar
atmosphere. Earth was hit by two CMEs on February 27 and 28. The
arrival of the first one was followed by a G1 to G2 class
geomagnetic storm, while the second was followed by a G3 class

"In the ever-growing sunspot group AR3234, already in the
northwestern solar disk, an M8.6-class solar flare with a possible
weak CME was observed at 1750 UTC on 28 February.

"Simultaneously, the Dellinger effect knocked out shortwave links at
frequencies up to 30 MHz around the Pacific Ocean with a duration up
to one hour.

"The CME is expected to arrive at Earth perhaps as late as March 4,
delivering only a glancing blow to the Earth's magnetic field.
Starting on March 4, a minor G1-class geomagnetic storm is likely.
Solar activity will not decrease, as another active region in the
southeastern solar disk will emerge in the meantime."

Here is a conversation about 6 meters:

"Gents, some 6M DX to report here at KM0T.

"Last few days, February 25-27, there was some DX worked locally so
I was trying to keep an eye on things. Then we got some aurora from
some flare impacts, and sure enough on the 27th got a few ZL and VK
decodes, lots of the Midwest worked some, but too scattered for me.
Also decoded FK8CP, who I have been chasing a card from a 2014 CW

"So Tuesday afternoon the 28th, was at the radio doing other shack
items when I saw a FT8 decode from VK4HJ at 2306 UTC working a W9
station. Proceeded to call him and worked at 2309 UTC with his -10
signal. Worked VK4WTJ at 2315 UTC with him coming in at -15.

"I then started to see decodes from FK8CP and FK8HA on and off for
the next 15 minutes. I worked FK8HA in RG37 with his -18 digs at
2344 UTC, I received a -20 report, took about 4 minutes once I got
his attention.

"During this whole time, I was calling FK8CP on and off between
trying others when they popped up. VK4MA came in at 2351 UTC with
his -09 digs. FK8CP was calling CQ WI all the time, but with FT8 you
can still answer, so I kept thinking why is he calling for
Wisconsin? Then figured that it was 'West Indies' (lol). He finally
relented and I worked him on FT8 around 0009 UTC with -13 sig report
from him.

"The whole thing about New Caledonia is that I worked FK8CP on 6M in
2014 on CW, but forgot back then to try for a card. Going through my
logs for 6M DXCC showed the errors of my ways and I started to send
cards back around 2020 since he was not LoTW. First one got returned
around 6 months later, the post master said he did not know why,
perhaps a typhoon. Then I tried again, but no answer for a long
time. Got returned again, about a year later. I thought perhaps he
was a SK, but his web page on QRZ did not leave any other contact
info other than regular mail.

"I forgot about it for a long time until I decoded him a few days
ago. I checked his QRZ page and it said due to Covid-19, mail has
been an issue for a very long time. So I got my card out and
readdressed a new envelope, went to the post office this morning and
mailed the card again. Wow, then I worked him that same day on FT8!
9 years later - too funny!

"73, Mike, KM0T.

"PS - Definitely F2, Not strong, but in and out. No Es to the SW
that I could tell. I worked VK and ZL on SSB 10 meters earlier,
about 2200 UTC with 80W. That band was in good shape and quiet, had
a 20 minute chat with a ZL with no QSB."

I (K7RA) asked, "When there is a geomagnetic storm and we see
openings on 6 meters, is it always due to auroral propagation?"

The response from Mike King, KM0T, to K7RA:

"Tad, in my experience on 6M, aurora gives your standard aurora
propagation early on during the actual aurora. Northern latitude
Midwest and NE - NW stations, with the typical auroral sound to SSB
and CW.

"Then later that same night we can get auroral-E skip, which may or
may not sound like aurora. Very typical to work Alaska later at
night after an aurora or auroral Es (at least from my location).

"Then after a night of aurora, I have always been on the lookout the
next day for F2/TEP/Chordal hop. When the flux is hovering around
160 or so, and there is really no F2 at 50 MHz from the Midwest, an
Aurora the previous day means that we got hit with a CME and the
whole thing could still be charged up. Thus when we get full
sunlight, I have seen many times F2/TEP propagation from the Midwest
that I would not normally get. It lasts just that one day typically
unless we get hit with more from the Sun.

"From here in the Midwest it's East or West F2 to Caribbean, Africa,
Indian Ocean, South America and Oceania. I don't believe I have seen
it to EU the next day.  (If you're in Texas, SW - SE, even better
for you - but they get that TEP much more than us...location,
location, location.)

"I have worked Scandinavia over the pole path a few times at
nighttime during an aurora via aurora-Es or F2, could never really
tell. So if E-skip it would be multi hop like a summertime day, but
had an auroral quality to those contacts. In my mind I always called
aurora enhanced F2.

"For me, having a decent aurora with flux being around 160, I feel
it's one of the best clues I get for looking for when 6M might do
wild things the next day. Throw this coming summertime auroras in
during the 6M E-skip season, those days after an aurora might be

"73 Mike, KM0T"

Here is a response from Jon Jones, N0JK:

"Tad, Mike:

"Agree with Mike's comments and good summary.

"The aurora geomagnetic activity can increase F-layer MUF,
especially when in the sunlight. Sometimes during an aurora F2 can
appear. The more common scenario is the one Mike describes. Aurora
during the night and F2 propagation the next day. That is what
happened Monday February 27.  Tuesday was some left over F2, K still

"Yesterday (March 1) the K index around 2. I copied Pipe, CE3SX for
4 FT8 sequences on 50.313 MHz at 2111 UTC. No luck with a contact.
Saw him send K0SIX (EN35) 'RR73.'

"Yes and left over F2 the 2nd day after the aurora like yesterday,
is normally only North South Propagation for me (Midwest) over the
TEP zone, which I worked one CE station for fun, decoded a bunch of
LUs, CX and CE, but had to leave for hockey practice."

Jon Jones added at 2035 UTC on Thursday:

"6 Meters popped open to Ecuador early in the afternoon March 2 on
F2. I was at work, able to take a break around 1910 UTC. Set up from
car - 1/4 wave whip and 10 watt MFJ-9406 radio. Many very loud
decodes on FT8 from Ecuador. Called several stations. At 1925 UTC
HC1DX called me on FT8 and we completed. Received a '-17 dB' report.
N0LL/P was on from rare grid EN01 and worked several in Ecuador.
Around 1900 UTC seems to be a good time frame for 6 Meter F2 to the

The phone portion of the ARRL DX Contest is this weekend.

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 February 23 through March 1 2023 were 108, 130,
129, 120, 192, 100, and 105, with a mean of 126.3. 10.7 cm flux was
148.2, 164.1, 152, 159, 161.2, 160.9, and 162, with a mean of 158.2.
Estimated planetary A indices were 22, 6, 10, 26, 94, 28, and 8,
with a mean of 27.7. Middle latitude A index was 16, 4, 9, 18, 60,
19, and 6, with a mean of 18.9.


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