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ARRL Propagation Bulletin ARLP040 (2022)

ARLP040 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 40  ARLP040
From Tad Cook, K7RA
Seattle, WA  October 7, 2022
To all radio amateurs 

ARLP040 Propagation de K7RA

Sunspot numbers and solar flux increased this week (September 29
through October 5), as expected with the solar cycle progressing
toward a probable peak in summer 2025.

Average daily sunspot number increased from 105.1 to 111.4, and
average daily 10.7 cm solar flux from 138.4 to 149.2.

Compare this to a year ago, when average daily sunspot number was
just 59.4 and solar flux was 89.8.

This last week there were two new sunspot groups on September 30,
one more on October 1, three on October 3, and one more on Thursday,
October 6.

I have been noticing improved 10 meter propagation with openings
lasting all day, now that the autumnal equinox passed two weeks ago
and with higher sunspot numbers.

Predicted solar flux is 156 on October 7, 154 on October 8 and 9,
then 152 and 150 on October 10 and 11, 148 on October 12 to 14, 130
on October 15, 135 on October 16 and 17, 140 on October 18, 145 on
October 19 to 21, 150 on October 22 and 23, then 145, 140 and 135 on
October 24 to 26, 145 on October 27 and 28, 150 on October 29, 155
on October 30 and 31, 145 on November 1, 135 on November 2 to 4, 130
on November 5 and 6, 135 on November 7, 140 on November 8 and 9, 130
on November 10 and 11 and 135 on November 12 and 13.

Predicted planetary A index is 14, 10, 12 and 8 on October 7 to 10,
5 on October 11 to 13, 8 on October 14, 10 on October 15 and 16,
then 8 on October 17 to 19, 12 on October 20 and 21, 8 on October 22
to 29, then 20, 12 and 10 on October 30 through November 1, then 8
on November 2 to 10 and 10 on November 11 and 12.

On October 2, announced "A Big Dangerous Sunspot",
AR3112, one of the biggest in years had just rotated over the sun's
eastern horizon.  They predict this could produce two weeks of high
solar activity.

F. K. Janda, OK1HH reports, "A week ago it seemed that following
conditions would be calmer.  This assumption was shattered after
AR3112 sunspot group, with its complex magnetic structure, began to
appear on the northeastern edge of the solar disk.

Prior to that, we expected the earth to be hit by a fast solar wind
from a CME that left the sun on September 28, but only a slight
increase in geomagnetic activity followed on September 28 and
October 2.

However, we did get an X1 flare on October 2 at 2025 UTC, which
ironically did not originate from the large dangerous AR3112 group,
but from the smaller and apparently less threatening AR3110 active
region.  It amplified the SWF (shortwave fade out) in the Pacific
and parts of North America.  Apparently, it blasted a CME into

This development was followed by the introduction of AR3112 with
over a dozen dark nuclei scattered over 130,000 km of the solar

It remained the case that most of the incoming CMEs were hurled into
space by the AR3110 group of spots, in which we observed a series of
strong flares (M5.9, M8.7, X1) over the weekend.

As a result, several CMEs headed towards Earth.

However, the geomagnetic field was only steady to active in the
following days.

Not only does the chance for energetic flares in the AR3112 region
persist, but on October 4, a 200,000 km long magnetic filament
erupted in the southern hemisphere of the Sun.  The plasma clouds
are not heading directly towards Earth, but some could hit on 8

Big filament.

The latest from WX6SWW, Space Weather Woman Dr. Tamitha Skov.

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 .

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bulletins are at .

Sunspot numbers for September 29 through October 5, 2022 were 56,
74, 100, 102, 144, 153, and 151, with a mean of 111.4.  10.7 cm flux
was 137.2, 137.1, 147.9, 153.9, 155.1, 152.4, and 161, with a mean
of 149.2.  Estimated planetary A indices were 7, 13, 3, 12, 24, 16,
and 14, with a mean of 12.7.  Middle latitude A index was 7, 12, 2,
9, 16, 13, and 11, with a mean of 10.


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