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The following is the weekly propagation bulletin from W1AW / ARRL (posting on 20230224 18:11 UTC):
QST de W1AW
Propagation Forecast Bulletin 8 ARLP008
>From Tad Cook, K7RA
Seattle, WA February 24, 2023
To all radio amateurs
SB PROP ARL ARLP008
ARLP008 Propagation de K7RA
Solar activity plunged this reporting week, although there was great
the excitement when the solar flux on February 17 was reported as a
record breaking 343.1.
Because it was the noon reading, it is still reported by NOAA as the
solar flux, but this was a false reading when the observatory at
Penticton, British Columbia was swamped by energy from a solar
flare.
So, in this report, I have chosen the 1800 UTC flux value, which was
165.
Average daily sunspot number plunged from 182.4 to 107, while
average solar flux dropped from 196.4 to 162.4. If I had not changed
the 343.1 to 165, solar flux average would have been 187.9, more
than 25 points higher than what we report here.
Six new sunspots emerged over the week, one on February 16, one each
on February 18 and 19, and three more on February 20, then one day
after the end of the reporting week, on February 23, two more
sunspot groups appeared.
The solar flux prediction for the next month shows a peak value of
180 for March 7-13.
Predicted values are 148 on February 24, 146 on February 25-27, 142
on February 28, 140 on March 1-2, 145, 150, 155, and 165 on March
3-6, 180 on March 7-13, then 175 and 170 on March 14-15, 160 on
March 16-17, then 155, 160, 150, 140 and 135 on March 18-22, 125 on
March 23-24, 130 on March 25, then 140 on March 26-28, 145 on March
29-30, then 150, 155 and 165 on March 31 through April 2. Beginning
on April 3, predicted flux values are back to 180, continuing into
the following week.
Predicted planetary A index is 10 on February 24-25, then 12, 18,
20, 16 and 10 on February 26 through March 2, 5 on March 3-4, then
15, 18, 15 and 8 on March 5-8, 5 on March 9-14, 15 on March 15, 8 on
March 16-17, 5 on March 18-20, 10 on March 21-23, 5 on March 24-25,
and 8 on March 26-27, then 5, 8, 5, 5, 15, 18, 15 and 8 on March 28
through April 4.
F.K. Janda, OK1HH wrote:
'A week ago, on February 17, we vainly awaited the arrival of a CME,
and at least a weak G1-class geomagnetic storm. Instead, on February
17 at 2016 UTC, we were treated to a strong X2.2-class solar flare
in the newly emerging sunspot group AR3229. X-ray and UV radiation
as well triggered the Dellinger Effect over the Americas. The
Dellinger Effect is a Sudden Ionospheric Disturbance.
'Frequencies up to 30 MHz were attenuated for more than an hour
after the flare. The arrival of the CME affected the Earth's
magnetic field at 1039 UTC on February 20. However, most of the
particle cloud passed outside the Earth, therefore there was no
geomagnetic storm, but only an increase in geomagnetic activity.
'The new AR3234 produced M-class flares in the following days.
Dellinger events could only affect radio wave propagation up to 20
MHz (as long as we had the Sun overhead, of course).
'Thereafter no significant flares were observed, so no CMEs were
directed toward us. But that may change when AR3234 turns toward
Earth. In other words, when the Sun's rotation moves it to the
central meridian, which will happen by the end of the week.
Primarily, the overall activity of the Sun and most likely the
Earth's magnetic field will depend on its activity.'
Jon Jones, N0JK wrote:
'There was a nice 6 meter F2 opening on February 16.
'I logged HC1MD/2 in grid FI57 on 50 MHz FT8 at 1916 UTC. I found
this opening by checking the DX Maps website. HC1MD/2 had a strong,
steady signal. I operated from home using an attic dipole antenna.
Also logged HC2FG.
'Other area 6 meter operators such as WQ0P (EM19) and KF0M (EM17)
also worked stations in Chile. The K index was 4, which I suspect
may have helped.
'On February 18 a number of North American stations worked Robert,
3B9FR around 1600 UTC on 6 Meter FT8.
'3B9FR is on Rodriguez Island in the Indian Ocean off the southeast
coast of South Africa.
'Conditions were great in the ARRL International DX CW Contest on 10
meters. I operated a couple of hours Sunday morning running 5 watts
and a quarter wave whip fixed mobile. Worked over a hundred stations
in Europe, the Caribbean, South America and Africa. Many of the
Europeans were over S-9.'
Dick, K2KA wrote:
'February 21 at 1544 UTC on 6 meters I worked FR4OO and then at 1558
UTC I worked 3B9FR. Both were FT8. I happened to be at the radio at
the right time. It was an amazing albeit brief opening here. They
were obviously new countries for me on 6 meters. They were #120 and
#121, respectively.
'My station here is IC-7610, ACOM 700s, antenna is a M2 6M7JHV 7el
on 30 ft. boom at 40 ft.'
A story about a Solar Tsunami:
https://yhoo.it/3EyYOxJ
A time-lapse video of a Flare:
https://bit.ly/3Ikc0aQ
Aki, JQ2UOZ wrote:
'Last weekend I participated in the ARRL International DX CW Contest
using an output power of 500 mW and a dipole antenna.
'The band conditions on 10m and 15m were amazing. I worked 9 East
Coast stations (VT, ME, DE, CT, NY, NH, PA, VA and FL) on 10m and 6
East Coast stations (MA, 2 NH, 2 PA and MD) on 15m. Usually, the
band conditions on 10m in February are not so good even at the
sunspot cycle maximum. This is the first time I worked East Coast
stations on 10m in the ARRL International DX CW Contest using 0.5W
and a dipole. Thanks to good-ears stations who worked me.'
Scott Hower wrote:
'With the exception of Thursday the 16th, 10 meters was hot this
week. On Wednesday February 15th I decoded 3A2MW in Monaco around
1233 to 1300 UTC using FT8 with his signal level as high as -13 dB.
This is the first time I have ever been able to receive Franco's
signal after years of trying on 10 meters. Unfortunately, he could
not receive me. 9N7AA has also been coming in every morning (except
the 16th) with levels as high as -1 dB using FT8 F/H. I finally
logged him on Friday the 17th.'
Scott did not mention his call sign, but I think he may be K7KQ.
Here is the latest report from Dr. Tamitha Skov, WX6SWW:
https://youtu.be/wm7tXN2EUCY
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 February 16 through 22, 2023 were 101, 86, 109,
112, 135, 106, and 100, with a mean of 107. 10.7 cm flux was 163.2,
165, 167.2, 169, 159.8, 160.9, and 151.9, with a mean of 162.4.
Estimated planetary A indices were 24, 6, 6, 7, 8, 17, and 6, with a
mean of 10.6. Middle latitude A index was 21, 4, 5, 4, 6, 15, and 4,
with a mean of 8.4.
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