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ARRL Propagation Bulletin ARLP030 (2022)

ARLP030 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 30  ARLP030
From Tad Cook, K7RA
Seattle, WA  July 29, 2022
To all radio amateurs 

ARLP030 Propagation de K7RA

Although images of the sun this reporting week, July 21 to 27,
showed plenty of sunspots, only two new spots emerged, one on July
21, and another on July 25.

Another new sunspot appeared on July 28, but the sunspot number
declined to 50 from 52 the day before.

Average daily sunspot number declined from 137.3 to 91.1, and
average daily solar flux softened by 50 points to 107.6.

The headline on on July 28 said, "Quiet Sun."

Geomagnetic indicators began this reporting week fairly active, with
planetary A index at 22, then it quickly quieted down to an average
of 11.7 for the week, higher than the 9.4 average reported last
week.  Average middle-latitude A index increased from 9 to 10.4.

A look back a year ago shows this cycle is progressing nicely.  In
ARLP030 in 2021 average daily sunspot number was just 48.9, and
average daily solar flux only 81.3.

A year prior the average daily sunspot number in 2020 was just 3.1!
That is because there were five days with no sunspots, then two days
with a sunspot number of only 11, which is the minimum non-zero
sunspot number.

A sunspot number of 11 does not mean 11 sunspots.  It means there
was just 1 sunspot group (which counts for 10 points) and one
sunspot in that group, counting for 1, producing a total of 11,
because of the arcane historical method of counting sunspots.

Predicted solar flux shows it peaking at 130 on August 11.

Predicted flux is 92 on July 29 to 31, 90 on August 1, 88 on August
2 to 4, 92 on August 5, 115 on August 6, 113 on August 7 and 8, then
120, 125, 130 and 125 on August 9 to 12, 120 on August 13 to 15, 118
on August 16 and 17, then 114 and 110 on August 18 and 19, 108 on
August 20 and 21, then 106 and 102 on August 22 and 23, 100 on
August 24 to 27, 108 on August 28 and 29, 110 on August 30 and 31,
115 on September 1 and 2, and 113 on September 3 and 4.  Solar flux
peaks again at 130 on September 7.

Predicted planetary A index is 8 and 12 on July 29 and 30, 8 on July
31 and August 1, 5 on August 2, 8 on August 3 and 4, 5 on August 5
to 10, 8 on August 11 and 12, 5 on August 13 to 16, 22 on August 17,
15 on August 18 and 19, 8 on August 20 and 21, 5 on August 22 to 25,
10 and 12 on August 26 and 27, 5 on August 28 and 29, 12 and 10 on
August 30 and 31, and 5 on September 1 to 6.

USAF/NOAA Solar Geophysical Activity Report, 2200 UTC on 28 Jul 2022

OK1HH wrote on July 28:

"Over the last seven days, solar activity has been steadily
decreasing.  From some class C flares to the 'almost no chance of
flares' announcement today.  But we observed some interesting
anomalies.  For example, geomagnetic disturbance on July 21 caused
two improvements in ionospheric shortwave propagation conditions
around 1400 and 1930 UTC.

A CME hit Earth's magnetic field on July 23rd at 0259 UTC.  The
impact triggered a G1-class geomagnetic storm and in the early hours
of the morning UTC, 6-meter band users were able to establish a
series of contacts between central Europe and the US East Coast.

The proton density in the solar wind, which suddenly rose on 27 July
between 2000 and 2100 UTC, was accompanied by a significant
improvement in shortwave propagation between Europe and the
Caribbean, while closed at the same time the path between Europe and
North America.

A small coronal hole of positive polarity located just to the north
of the solar equator that crossed the central meridian on July 26 is
expected to influence solar wind starting July 29.  Geomagnetic
activity will increase again."

KD6JUI wrote:

"I go out in my kayak once per week to operate QRP.  Today,
Thursday, July 28, I set out on Lake Solano (northern CA) not
expecting much action due to a low solar flux (93.4) and predicted
MUF of about 14 MHz.

When I first checked 17m I heard a CW pileup apparently going after
a Swiss station.  I had a couple contacts on 17 and 20m.  A couple
hours later, I moved from the middle of the lake to the shade of a
tree along the bank (temps were in the high 90s).  My loop antenna
was half surrounded by foliage, which I figured would interfere with
my signal.  Nonetheless, I gave 17m CW a try again, and contacted
F8IHE almost immediately.  All he could copy was my call sign, but
that was enough for me! 

Always a surprise."

What are sunspots?

Fun Morse Code app:

A fun one-hour twice weekly relaxed CW activity, the Slow Speed
Test, every Friday and Sunday:

Send your tips, reports, observations, questions and comments to

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 July 21 through 27, 2022 were 124, 107, 96, 80,
100, 78, and 53, with a mean of 91.1.  10.7 cm flux was 121.7,
114.7, 110.5, 107.1, 102.3, 98.8, and 98, with a mean of 107.6.
Estimated planetary A indices were 22, 11, 17, 9, 6, 8, and 9, with
a mean of 11.7.  Middle latitude A index was 14, 11, 15, 9, 8, 7,
and 9, with a mean of 10.4.


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