XPost: rec.radio.shortwave, rec.radio.info

SB PROP @ ARL $ARLP016
ARLP016 Propagation de K7RA

ZCZC AP16
QST de W1AW
Propagation Forecast Bulletin 16 ARLP016

From Tad Cook, K7RA

Seattle, WA April 22, 2022
To all radio amateurs

SB PROP ARL ARLP016
ARLP016 Propagation de K7RA

Solar flares emerged daily over the last reporting week (April
14-20). On April 20 Spaceweather.com reported "Solar Activity is
Intensifying," and that over the past 24 hours there were 19 solar
flares, including six M-class events, and a powerful X2.2 class
flare.

Daily sunspot numbers averaged 64.4, 30 points higher than last
week, and average daily solar flux also rose 30 points from 103.1 to
133.9.

Yesterday, April 21, the huge array of active Earth facing sunspots
pushed the daily sunspot number clear up to 119, high above the
average for the week of 64.4.

Even with all the flares and CMEs, geomagnetic indicators were
lower, with the average planetary A index going from 16.9 to 14.6,
and middle latitude numbers from 12.6 to 10.9.

Predicted solar flux looked moderate, but the outlook improved
between April 20 and the following day, with flux values at 160 on
April 22-29, 125 on April 30, 130 on May 1-4, 125 on May 5, 130 on
May 6-7, 128 on May 8, 130 on May 9-10, 135 on May 11-12, 140 on May
13-14, 135 on May 15, 130 on May 16-18, 135 on May 19, 130 on May
20-21, 135 on May 22, 132 on May 23-25, 125 on May 26-27, and 130 on
May 28-31.

Predicted planetary A index is 5 and 12 on April 22-23, 12 on April
23, 8 on April 24-25, 5 on April 26-28, then 18, 12 and 8 on April
29 through May 1, 5 on May 2-5, then 8, 15, 12 and 8 on May 6-9, 5
on May 10-12, then 8, 10 and 12 on May 13-15, 10 on May 16-17, 8 on
May 18-19, then 12 and 8 on May 20-21, 5 on May 22-25, then 18, 12
and 8 on May 26-28.

This report from OK1HH:

"A week ago, we knew solar activity would rise, but the reality
exceeded expectations. As predicted, a CME hit Earth's magnetic
field on April 14th. Its impact sparked a moderately strong G2-class geomagnetic storm, which peaked around 1800 UTC. Apparently due to
the further increasing solar radiation, the disturbance was mainly
accompanied by an improvement in the ionospheric propagation of
decameter waves (10 meters!), which also applied to the following
development.

"Activity prevailed in growing hotspots in the northeast quadrant of
the solar disk. In the following days, the activity of the
southwestern areas increased, including the X2.2-class flare on
April 20th at 0357 UTC, when it came from a far side sunspot. And
finally, on April 21st at 0157 UTC a strong M9.6-class solar flare
was detected. The source was the sunspot complex AR2993-94, which is
almost directly facing Earth, so I expect the intensified solar wind
in the coming days to affect the Earth's magnetosphere and
ionosphere."

Solar flares in the news:

https://www.space.com/sun-unleashes-major-easter-solar-flare

Here is an impressive image:

https://skyandtelescope.org/online-gallery/sun-erupting/

Here are more and more solar flares:

https://www.space.com/solar-x-class-flare-april-2022

https://www.space.com/sdo-image-april-20-moderate-flare

Funny thing is, even with all this activity, I am not seeing much of
an effect on geomagnetic indicators:

https://services.swpc.noaa.gov/text/daily-geomagnetic-indices.txt

More solar news can be found here:

https://bit.ly/3jZtEVF

https://interestingengineering.com/sun-flare-five-years

If you would like to make a comment or have a tip for our readers,
please email the author at, k7ra@arrl.net.

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals. For
an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .

Sunspot numbers for April 14 through 20, 2022 were 37, 35, 78, 74,
79, 68, and 80, with a mean of 64.4. 10.7 cm flux was 103.4, 110.3,
122.4, 134.9, 140.5, 160.1, and 165.5, with a mean of 133.9.
Estimated planetary A indices were 38, 21, 8, 11, 8, 7, and 9, with
a mean of 14.6. Middle latitude A index was 22, 14, 7, 9, 7, 8, and
9, with a mean of 10.9.
NNNN
/EX

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XPost: rec.radio.shortwave, rec.radio.info

SB PROP @ ARL $ARLP016
ARLP016 Propagation de K7RA

ZCZC AP16
QST de W1AW
Propagation Forecast Bulletin 16 ARLP016

From Tad Cook, K7RA

Seattle, WA April 21, 2023
To all radio amateurs

SB PROP ARL ARLP016
ARLP016 Propagation de K7RA

Again this week sunspot numbers and solar flux were higher than the
week before.

Average daily sunspot numbers more than doubled, from 70.6 to 146.9,
and average daily solar flux increased from 141 to 164.5. Both
figures represent a substantial increase in solar activity.

Planetary A index averages went from 7.6 to 8.1, while middle
latitude A index advanced from 6.4 to 7.3.

Three new sunspot groups emerged on April 13, one more on April 16,
and another on April 17.

Predicted solar flux over the next few weeks is 145, 140 and 135 on
April 21-23, 130 on April 24-25, 125 on April 26-27, 160 on April
28-29, 165 on April 30, 172 on May 1-3, 170 on May 4, 172 on May
5-7, 178 on May 8, 182 on May 9-12, then 175, 178 and 170 on May
13-15, 168 on May 16-17, 175 on May 18, then 172 on May 19-21, then
168 and 162 on May 22-23, 160 on May 24-26, 165 on May 27, and 172
on May 28-30.

Predicted planetary A index is 20, 16, 12 and 8 on April 21-24, 5 on
April 25-27, 15 on April 28-30, then 12 and 10 on May 1-2, 8 on May
3-4, 5 on May 5-6, 12 on May 7, 5 on May 8-10, then 8 on May 11-12,
5 on May 13-18, then 10, 8, 5 and 5 on May 19-22, 15 and 18 on May
23-24, 15 on May 25-27, then 12 and 10 on May 28-29.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - April 20, 2023 from OK1HH.

"Of the fifteen sunspot groups observed over the past week, AR3272
and AR3282 were the source of most of the flares. Both had a
beta-gamma magnitude configuration. 61 C-class flares and 4 M-class
flares were observed.

"The partial halo CMEs on 15 and 16 April were the source of
particles that reached Earth on 18 April, when the solar wind speed
increased abruptly at 1308 UTC and a geomagnetic disturbance
developed.

"A positive phase of the ionospheric disturbance was recorded on the
afternoon of 18 April, followed by a negative phase on 19 April.
This was followed on 20 April with a significant increase in f0F2
and improved shortwave propagation conditions before noon UTC.

"The outlook looks promising for the first half of May, when solar
activity should increase further."

Dan Handa, W7WA commented on the news last week about the current
solar cycle reaching a peak earlier than predicted, perhaps by the
end of this year.

I told him I hoped it would not peak early, because I wanted to see
several more years of increasing activity.

Dan sent a very detailed graph of Solar Cycle 19 from 1954 to 1966,
and wrote: "I have read, and more than once, a slow rise means a low
sunspot max. The previous Solar Cycle 24 took five years to reach a
relatively low maximum. A rapid increase can mean a high sunspot
maximum. The granddaddy of our lifetime, Solar Cycle 19 peaked in
three years!"

I did not know this.

In a subsequent message, Dan further commented:

"There was a lot of short term variation in the Solar Cycle 19
sunspot number, just like we're seeing now. From the graph the
timing of the Solar Cycle 19 peak can be defined three different
ways: the daily peak, the smoothed monthly peak or the smoothed
yearly peak, take your pick."

Another Solar Cycle 19? Many hams have dreamed of this for the past
six decades.

Dale, WB6MMQ reported that the solar images in the ARRL Letter with
a preview of our Friday bulletin show a blank Sun. I wasn't sure
what he was talking about, but now I realize this must be a stock
image (not from me!) used in the Letter.

I sent Dale links to some recent images from Spaceweather.com:

https://www.spaceweather.com/images2023/20apr23/hmi1898.gif

https://www.spaceweather.com/images2023/19apr23/hmi1898.gif

https://www.spaceweather.com/images2023/18apr23/hmi1898.gif

https://www.spaceweather.com/images2023/17apr23/hmi1898.gif

I hope this clears up the confusion.

An odd correlation between an ancient epidemic and solar activity:

https://bit.ly/3Lsqfxf

A story about a possible early Solar peak:

https://www.space.com/sun-solar-maximum-may-arrive-early

A story about possible M-class solar flares:

https://bit.ly/3KVc1n1

Send your tips, reports, observations, questions and comments to
k7ra@arrl.net. When reporting observations, don't forget to tell us
which mode you were operating.

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information
Service at http://arrl.org/propagation-of-rf-signals . For an
explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere .

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation . More good
information and tutorials on propagation are at http://k9la.us/ .

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .

Sunspot numbers for April 13 through 19, 2023 were 154, 153, 151,
155, 162, 140, and 113, with a mean of 146.9. 10.7 cm flux was
159.5, 171.3, 175.8, 177.8, 166.6, 153.2, and 147, with a mean of
164.5. Estimated planetary A indices were 6, 7, 9, 4, 6, 13, and 12,
with a mean of 8.1. Middle latitude A index was 5, 10, 8, 4, 6, 9,
and 9, with a mean of 7.3.
NNNN
/EX

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XPost: rec.radio.shortwave, rec.radio.info

SB PROP @ ARL $ARLP016
ARLP016 Propagation de K7RA

ZCZC AP16
QST de W1AW
Propagation Forecast Bulletin 16 ARLP016

From Tad Cook, K7RA

Seattle, WA April 19, 2024
To all radio amateurs

SB PROP ARL ARLP016
ARLP016 Propagation de K7RA

Solar activity increased dramatically this reporting week (April
11-17), and thirteen new sunspot groups emerged. One appeared on
April 11, two more on April 13, three more on April 14, another two
on April 15, one more on April 16 and another two on April 17. On
April 18 an additional two sunspot groups emerged, and the daily
sunspot number increased to 247.

The daily sunspot number was 199 on April 17, the highest value
since July 12, 2023 when it was 219. On April 18, when the sunspot
number was 247, it was the highest sunspot number since July 6, 2014
when it was 256. That was back in Solar Cycle 24, so 247 is a new
record for Solar Cycle 25.

Average daily sunspot numbers jumped from 67.9 to 142.7, and average
daily solar flux from 123.2 to 177.4.

Predicted solar flux over the near term is 225 on April 19, 220 on
April 20-21, 215 and 205 on April 22-23, 190 on April 24-25, then
140, 130, 125 and 120 on April 26-29, then 125 on April 30 to May 6,
and 130, 140, 150, 160 and 175 on May 7-11, then 180 on May 12-14,
175 on May 15, 170 on May 16-17, then 167 and 165 on May 18-19, 160
on May 20-21, then 155, 140, 135, 125 and 120 on May 22-26.

Predicted planetary A index is 6, 10, 12 and 8 on April 19-22, 5 on
April 23-27, 8 on April 28-29, 7 on April 30, 10 on May 1-3, 5 on
May 4, 8 on May 5-7, 5 on May 8-11, 10 and 8 on May 12-13, then 5 on
May 14-24, and 8 on May 25-26.

"Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - April 18, 2024:

"Over the past weekend, active sunspot regions began to emerge on
the eastern limb as expected. Curiosity about what we would actually
see was heightened because their flare activity during the last
rotation was somewhat higher than usual. Therefore, the CME from a
moderate eruption in the northern hemisphere of the Sun on April 11
with a maximum at 1706 UTC was not a surprise. The arrival of the
particle cloud on April 14 was therefore expected, but it missed the
Earth.

"Another CME was ejected towards Earth on 12 April. Although neither
CME was particularly strong, a G1 class geomagnetic storm was
expected. This occurred on 16 April, so either the particle cloud
moved more slowly or traveled along a longer path toward the Earth.
Either way, the disturbance worsened shortwave propagation on April
16. But the improvement was rapid, starting as early as April 17.
The credit for this goes to the increasing solar radiation coming
from the active regions we can observe on the Sun this week and
next.

"Another weak CME left the Sun on April 15, and the Earth's impact
was calculated for April 18. However, all predictions of
disturbances at the current stage of the 11-year cycle are
unreliable. They are usually either late (by a day or so) or not at
all. The important thing is the result - due to the relatively high
solar activity and at the same time the small number of geomagnetic disturbances, the shortwave propagation conditions are mostly above
average. F.K. Janda, OK1HH."

Check out these videos and an article on flare activity from
EarthSky:

https://bit.ly/3W4GTID

On April 16, Samuel, K5KJ called ARRL headquarters about unusual
propagation he experienced.

He said flare activity caused a radio blackout, and on 40 meters he
could not hear any local or regional signals.

But he noticed foreign broadcast stations from Asia with good
signals.

He said this is just the opposite of what he expected during a
blackout.

Durango Herald article about sunspots and prominences:

https://bit.ly/3Q3VDnh

NASA on Space Weather:

https://go.nasa.gov/49YFhDX

From Science.Nasa.gov, Solar Moss:

https://go.nasa.gov/4b3n4Wn

See sunspots with eclipse glasses:

https://bit.ly/4cXc5Qp

I tried this, but had no luck, as the images were too tiny.

The latest video from Dr. Tamitha Skov, WX6SWW, for April 14:

https://youtu.be/Z1OClNvDg2o

Send your tips, reports, observations, questions, and comments to k7ra@arrl.net. When reporting observations, don't forget to tell us
which mode you were operating.

For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals . For
an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere .

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation . More good
information and tutorials on propagation are at http://k9la.us/ .

Also, check this QST article about Solar Indices:

https://bit.ly/3Rc8Njt

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .

Sunspot numbers for April 11 through 17 2024 were 81, 83, 115, 152,
193, 176, and 199, with a mean of 142.7. 10.7 cm flux was 143.7,
151.5, 161, 178.4, 191.9, 198.7, and 216.5, with a mean of 177.4.
Estimated planetary A indices were 6, 7, 5, 6, 8, 31, and 7, with a
mean of 10. Middle latitude A index was 6, 6, 6, 5, 7, 17, and 8,
with a mean of 7.9.
NNNN
/EX

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