[SFDXA] ARLP007 Propagation de K7RA

Fri Feb 16 11:11:02 EST 2024

SB PROP @ ARL $ARLP007
ARLP007 Propagation de K7RA

ZCZC AP07
QST de W1AW
Propagation Forecast Bulletin 7  ARLP007
 From Tad Cook, K7RA
Seattle, WA  February 16, 2024
To all radio amateurs

SB PROP ARL ARLP007
ARLP007 Propagation de K7RA

Seven new sunspot groups appeared over the past week, February 8-14, two 
on February 8, three on February 10, and two more on February 13 and 14.

Then on February 15 three more sunspots emerged.

Now this is a personal opinion, but from recent numbers I suspect that 
we may at the peak of Solar Cycle 25 or just prior to the peak. We won't 
know when the actual peak occurred until six months after.

Average daily sunspot number declined from 142.3 to 134.6, but average 
daily solar flux increased from 165.5 to 190.

I don't know why the solar numbers were so seemingly out of whack, but 
average daily sunspot number declined as average daily solar flux rose, 
by a lot.

Average daily planetary A index rose from 5.1 to 7.4, while middle 
latitude numbers from 4.4 to 6.1.

The most active day was February 11 with planetary A index rising to 15, 
but that is hardly stormy. This was caused by an unexpected CME impact 
at 0211 UTC according to Spaceweather.com.

So, what is the outlook for the next few weeks?

Concerning solar flux, it seems we are currently in the midst of a peak 
over the next few days at 185 and 182 on February 15-16, then another 
short term peak at 170 on March 3-10.

On February 17-23 the forecast sees the flux at 175, 172, 170, 165, 175, 
165 and 160, then 150 on February 24-28, then 155, 160 and 165 on 
February 29 through March 2, then 170 on March 3-10, 165 on March 11-3, 
170 on March 14, 160 on March 15-19, then 162, 165 and 160 on March 20-22.

Predicted planetary A index is 5 on February 16-18, 8 on February 19, 5 
on February 20-25, then 8 and 7 on February 26-27, then 5 on February 28 
through March 23.

This is the same data that appeared in the ARRL Letter on Thursday, 
which was the report from February 14.

Unfortunately, NOAA did not post the updated forecast on Thursday. 
Thursday evening, I phoned the NOAA forecast desk, and they didn't have 
the data from US Air Force. I then phoned the 557 Weather Wing at Offutt 
Air Force Base and was told they had a major network outage Thursday 
afternoon, and the data may be lost.

Fortunately, the phone numbers at both locations are answered 24-7.

If you need an updated forecast, check: 
https://services.swpc.noaa.gov/text/45-day-ap-forecast.txt

It is normally updated every day after 2200 UTC.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's 
Ionosphere - February 15, 2024 from OK1HH:

"Over the past week, we saw the transition of two large active regions 
with complex magnetic configurations on the solar disk: AR3575 followed 
by AR3576, which will be at the western limb of the disk on February 16.

"More massive flares, including proton flares accompanied by CME were 
observed in both regions. Protons from the flares bombarded the Earth's 
atmosphere for most of the days. CMEs, however, hit the Earth with 
little or no impact. This included a strong X3.4 class solar flare 
followed by a S2 class radiation storm on 9th February. Energetic solar 
protons impacted the upper layers of the Earth's atmosphere and caused 
mainly polar cap absorption (PCA). This significantly increased the 
attenuation of radio signals at high latitudes.

"We could also guess whether the CMEs were just delayed since the 
eruptions of 9 and 10 February and would not arrive until 13 February, 
or whether they would miss the Earth. NASA guessed that they would 
arrive. But the correct answer was they missed, which was confirmed by 
the more or less calm development on 14 February.

"After the sunset of the two large active regions AR3575 and AR3576, 
solar activity will decrease. However, helioseismological observations 
indicate the presence of active regions on the far side of the Sun. 
After their ascent to the solar disk, solar activity will increase again 
since early March. Solar activity should be highest between March 3 and 
10. Meanwhile, geomagnetic activity should continue to be low. 
Therefore, we expect an improvement in shortwave propagation conditions.

"F.K. Janda, A.R.S. OK1HH,http://ok1hh.nagano.cz/"

This weekend is the CW portion of the ARRL International DX contest. 
Details can be found at: https://www.arrl.org/arrl-dx

Two articles about a CME and flares: https://bit.ly/3OHvtpZ 
https://bit.ly/49zgoia

Three days of sunspots: https://bit.ly/3SJhbGi

Multiple pictures of Sunspot region 13585: https://bit.ly/3UFVhGQ

Bob, KB1DK, from Connecticut wrote: "During the last two weeks, activity 
on 10 meter SSB was bustling, and included many POTA, SOTA, and mobile 
stations in Europe. In fact, I heard Europeans on 12 meters saying they 
moved to that band because 10 became so busy. Propagation on 10 has been 
very good from southern New England, resulting in multiple QSOs with 
India and New Zealand. QSOs with the middle east are almost routine now.

"My occasional fixed mobile operating has been extremely productive and 
satisfying. I strongly recommend taking advantage of these great 
conditions on 10 meters while we have them."

Send your tips, reports, observations, questions, and comments to 
k7ra at 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/propagationand 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 athttp://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 athttp://arrl.org/bulletins.

Sunspot numbers for February 8 through 14 2024 were 149, 105, 146, 144, 
153, 122, and 123, with a mean of 134.6. 10.7 cm flux was 185, 183.4, 
193.8, 180.4, 208.3, 194.8, and 184.1, with a mean of 190. Estimated 
planetary A indices were 5, 6, 5, 15, 4, 10, and 7, with a mean of 7.4. 
Middle latitude A index was 5, 4, 4, 12, 4, 8, and 6, with a mean of 6.1.
NNNN
/EX
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