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 [email protected]. 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 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