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ARRL Propagation Bulletin ARLP013 (2022)

ARLP013 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 13  ARLP013
From Tad Cook, K7RA
Seattle, WA  April 1, 2022
To all radio amateurs 

ARLP013 Propagation de K7RA

Many solar flares and CMEs occurred over the reporting week (March
24-30) but with glancing blows and near misses, it wasn't reflected
in the geomagnetic indicators until Thursday, the last day in March.

Planetary A index reached a high for the reporting week of 19 on
March 27. Average daily planetary A index rose by a modest amount
from 6.3 to 10.

Average daily sunspot number rose from 33.4 to 80.1, while solar
flux went from 99.9 to 132.7.

The rising solar activity brought us a tremendous amount of 10 meter
coverage. Every day I have received reports from all over North
America from operators hearing my K7RA/B propagation beacon on
28.2833 MHz.

Predicted solar flux is 150, 145, and 130 on April 1-3, 115 on April
4-5, 110 on April 6-8, then 118, 115, and 110 on April 9-11, 105 on
April 12-14, 108 on April 15, 105 on April 16-19, 110 on April
20-21, 115 on April 22, 125 on April 23-26, then 123, 118 and 118 on
April 27-29, then 108 on April 30 through May 2, 112 on May 3, 115
on May 4-6, and 112 on May 4, then dropping to 105 through the
middle of May.

Predicted planetary A index is 32, 10, 15 and 10 on April 1-4, 819,
on April 5-6, 5 on April 7-19, 10 on April 20-21, then 5, 15 and 10
on April 22-24, then 5 on April 25-29, 12 and 8 on April 30 and May
1, and 5 0n May 2-15.

Report from F.K. Janda, OK1HH:

"We have a week of somewhat wilder development behind us. Its first
indication were two sunspot groups on the northeastern limb of the
solar disc on March 24. The second of them, region 2976, was larger.

"Region 2975 had a more complex magnetic structure and grew
gradually. A proton solar flare was observed on March 28 at 1129
UTC, accompanied by a significant increase in proton levels. And
above all, it was followed by a CME heading to Earth!

"Exactly as predicted, the arrival of the CME caused a geomagnetic
disturbance on March 31. Its positive phase of development was
accompanied, especially in the UTC morning hours, by a significant
improvement in the shortwave propagation conditions on a global

"Another solar flare was observed in the same area on March 30 with
a maximum at 1737 UTC. Although X-ray levels rose more than on March
28, followed by CME again (albeit weaker, at 1823 UTC), there is no
expectation that it would be followed by a similar increase in
geomagnetic activity."

Angel Santana WP3GW of Trujillo Alto, Puerto Rico wrote:

"For the contest this past weekend, conditions were pretty decent.
10 meters was good as on past October, but propagation is still
coming up, as stations were as high at 28.6 MHz, but on a great
season stations would be heard beyond 29 MHz. With the new radios
that have spectrum analyzers you can view this. On Sunday at 1420
UTC I contacted a few European stations and even a 4X.

"When I went to 15/20 meters, I had 85 percent success in contacting
the stations. In all 324 stations and 64 DXCC entities, despite

"And these days, there are a few stations from Spain on 10 meters at
2000 UTC which is their local 10 PM. Really big signals. Solar Cycle
25 is almost at full swing."

LA4LN reports 6 meter TEP activity.

"We see that stations in southern Europe are reporting contacts with
southern Africa and South America, across the magnetic equator.

"Likewise, we see that US stations are making TEP contacts with
stations in South America across the magnetic equator, with no F2
propagation possible on 50 MHz at this time, with too low SFI (Solar
Flux Index) for 50 MHz F2 propagation.

"Seeing more TEP 'heard and worked' between southern Europe and
southern Africa on the 6 meters band, across the magnetic equator

I often see references to the "magnetic equator" but did not know
what it was. This gives a good explanation:

More from LA4LN:

"In last week's bulletin you reported from N0JK his proposal of the
first F2 openings on 50 MHz in Solar Cycle 25.

"It must be mentioned that the SFI has been near 100 (he reported
95), and this is most likely a too low SFI to cause F2 propagation
on 50 MHz, according to our experience.

"Instead, we have during the last few weeks had numerous reports of
TEP (Trans Equatorial Propagation) on 50 MHz, with radio amateurs in
mainly the southern states of USA working South America - and with
radio amateurs in southern Europe working southern Africa and South

"It is important to note that the TEP is aligned over the magnetic
equator on Earth (not aligned over the geographic equator). TEP is
well described in the ARRL literature."

We normally get our 10.7 cm solar flux straight from the source, the
DRAO observatory in Penticton, British Columbia:

But since March 18, there has been no new data, so we rely on NOAA
as a secondary source, which is why we have recently presented solar
flux numbers that are not resolved to 0.1 but instead are from this
source, which is also our source for daily sunspot numbers:

DRAO Penticton has not answered any email inquiries or phone calls,
so we wait.

Some of the interesting articles and images this week:

NN4X sent a pskreporter map showing his 10 meter signal at 1710 UTC
on March 29 being received all around the world, including South
Africa, Europe, Southeast Asia, South America and across North

That was one of many, many 10 meter reports this week.

An exciting new report from Dr. Tamitha Skov, WX6SWW:

If you would like to make a comment or have a tip for our readers,
please email the author at,

For more information concerning shortwave radio propagation, see and the ARRL Technical Information
Service web page 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 24 through 30, 2022 were 44, 50, 48, 97,
125, 124, and 73, with a mean of 80.1. 10.7 cm flux was 112, 112,
119, 130, 156, 149, and 151, with a mean of 132.7. Estimated
planetary A indices were 9, 10, 7, 18, 10, 8, and 8, with a mean of
10. Middle latitude A index was 6, 3, 6, 11, 4, 7, and 6, with a
mean of 8.1


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