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ARRL Propagation Bulletin ARLP006 (2023)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 10, 2023
To all radio amateurs 

ARLP006 Propagation de K7RA

A period of rising solar activity returned this week.

Ten new sunspot groups appeared this reporting week (February 2-8),
two on February 3, one each on February 4-5, four more on February
6, and two more on February 8.

On February 9, three more sunspot groups emerged.

Early on February 9 reported a large emerging
sunspot over our Sun's southeast horizon.

Average daily sunspot number this week rose from 80.7 to 95.1, and
average daily solar flux from 139.5 to 155.9.

On Thursday, February 9 both the sunspot number and solar flux were
above the average for the previous seven days. Sunspot number at 150
compared to the average 95.1 and solar flux at 214.9 compared to the
average of 155.9. Both indicate an upward trend.

Geomagnetic indicators rose, planetary A index from 7.9 to 11.7,
middle latitude numbers from 5.9 to 7.6.

The rise in geomagnetic activity was related to solar wind late in
the reporting week.

The solar flux prediction on Wednesday was 192 for February 9 (the
actual noon solar flux was 214.9), then 195 on February 10-13. As
you can see below, the Thursday prediction is more optimistic for
the next few days.

Predicted solar flux is 214 on February 10, 212 on February 11-13,
then 208, 205 and 202 on February 14-16, 150 on February 17-18, then
145, 140, 135, 130 and 135 on February 19-23, 130 on February 24-26,
125 on February 27, 130 on February 28 through March 3, then 135,
150 and 160 on March 4-6, 155 on March 7-8, 160 on March 9, and 155
on March 10-12, then 150 on March 13-17.

Predicted planetary A index is 12 and 8  on February 10-11, then 5
on February 12-17, 8 on February 18-19, 5 on February 20-21, 10 on
February 22-24, then 5, 5 and 8 on February 25-27, and 5, 5, and 8
on February 28 through March 2, then 5, 5, and 10 on March 3-5, then
15, 15, 12 and 8 on March 6-9, then 5 on March 10-16, 8 on March
17-18, 5 on March 19-20 and 10 on March 21-23.

F.K. Janda, OK1HH wrote:

"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - February 9, 2023.

"Solar activity was lower between 26 January and 6 February, as
expected. Two weeks ago, large sunspot groups AR3190 and AR3192,
fell behind the Sun's western limb. They have now appeared near the
eastern limb as AR3217 and AR3218. In particular, the region of
AR3217 was already letting us know of its activity with plasma
bursts before we could observe it.

"Thereafter we observed moderate flares in it. AR3217 and AR3218
will now move through the solar disk, and the increase in solar
activity will continue.

"On February 7, rapidly developing sunspot group AR3213 suddenly
appeared, where at most only two small spots could be observed
shortly before. Medium-sized flares were observed in AR3213 in the
following days.

"Another new activity was the increase in the Earth's magnetic field
activity starting on February 6.

"The subsequent increase in the MUF (highest usable frequencies of
the ionospheric F2 layer) has been slow and irregular so far. We
will have to wait a few more days for its higher values."

Check out Scott Craig, WA4TTK and his Solar Data Plotting Utility.
He wrote it several decades ago back in the days of MS-DOS, and the
Windows version still works today. It displays sunspot numbers and
solar flux all the way back to January 1, 1989:

Click the "Download SOL313W.ZIP" file to install the program, then
download the updated GRAPH.dat file for the latest data. It is
updated to last week, so you can try out the data insertion on this

He posted a new copy of the data file, provided by N1API.

The utility will update the data every week by pointing it toward a
copy of our bulletin in .txt format.

The GRAPH.dat file is in text format and can be imported into a
spreadsheet program to display the data any way you want.

Tech Times and articles on a Radio Blackout:

KB1DK sent this article about something occurring on our Sun:

Larry, W0OGH in Cochise County, Arizona wrote:

"Who says you can't have fun running QRP?

"I started playing with QRP on CW, my KX3 at 10W and 10M 4 element
Yagi just after February 1.

"Why so late in the game? I don't know but maybe it was because the
signals took such an upturn in strength.

"Have been working some POTA stations QRP but no DX until February 1
when I worked E77DX, OK9PEP, PA1CC, DS2HWS, UA1CE, YL3FT, UY2VM,
more, all on 10 meters.

"But the kicker and best of all was working EP2ABS on the morning of
2/6/23 at 1654 UTC on 28.0258 MHz.

"First time ever in 65 years that I have ever worked an Iran station
much less heard one. He was really strong and calling CQ getting no
answers. At the same time I called him, another station called as
well but he came back to me.

"Thereafter he had a pileup, but his signal started dropping off, so
I caught him at the right time. Maybe a duct? Yep, the DX is out
there on 10M and when the band is hot, you gotta be there.

"I have even worked some AM stations on and above 29.000 MHz with
QRP. Lots more fun than high power which in my case is 100W from my

A friend here in Seattle worked him on the same day, was very
surprised, and mentioned a friend in California who worked EP2ABS
with 100 watts and an 18 foot wire.

Another "news" source reporting rising solar activity as some sort
of existential threat:

A more reliable source:

Dr. Tamitha Skov's, WX6SWW, latest report from February 5:

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 2 through 8, 2023 were 56, 74, 66, 79,
139, 110, and 142, with a mean of 95.1. 10.7 cm flux was 134.9,
134.5, 139, 144, 156.7, 184.7, and 197.6, with a mean of 155.9.
Estimated planetary A indices were 6, 9, 6, 5, 18, 20, and 18, with
a mean of 11.7. Middle latitude A index was 2, 6, 5, 3, 13, 12, and
12, with a mean of 7.6.


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