Solar activity was up this week, with the average daily sunspot number increasing from 133.7 to 139, and average daily solar flux from 155.3 to 166.8. Average daily planetary A index stayed the same at 7.3, and average middle latitude A index went from 7.9 to 8.6. Predicted solar flux doesn't show any improvement, with peaks at 170 on June 23-25 and July 20-21.
Propagation Forecast Bulletin #23 de K7RA:
QST de W1AW
Propagation Forecast Bulletin 23 ARLP023
From Tad Cook, K7RA
Seattle, WA June 9, 2023
To all radio amateurs
SB PROP ARL ARLP023
ARLP023 Propagation de K7RA
Solar activity was up this week, with the average daily sunspot number increasing from 133.7 to 139, and average daily solar flux from 155.3 to 166.8.
Average daily planetary A index stayed the same at 7.3, and average middle latitude A index went from 7.9 to 8.6.
Predicted solar flux doesn't show any improvement, with peaks at 170 on June 23-25 and July 20-21.
The forecast shows solar flux at 168, 163, 157, 160, 157, 153, 160 and 150 on June 9-16, 155 on June 17-20, then 160 and 165 on June 21-22, 170 on June 23-25, then 168, 165 and 162 on June 26-28, 160 on June 29 through July 4, then 155, 150 and 145 on July 5-7, then 140, 135, 140, 143, 145 and 150 on July 8-13, and 155 on July 14-17.
Predicted planetary A index is 8, 5, 10 and 8 on June 9-12, 5 on June 13-17, then 22, 15, 12 and 10 on June 18-21, 5 on June 22-26, then 10, 12, 5 and 5 on June 27-30, then 8, 12 and 8 on July 1-3, and 5 on July 4-7, then 10, 12 and 8 on July 8-10, and 5 on July 11-14, then 22. 15. 12 and 10 on July 15-18.
In some previous bulletins I was reporting 10 meter propagation observed with FT8 only into Florida from my QTH in Seattle, and also into Mexico at a similar distance.
Recently on 10 meters I am seeing propagation into VK/ZL, and in North America mostly into Southern California, Nevada, Utah and Arizona. Some seasonal variation, I suppose.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere - June 8, 2023 from OK1HH:
"In the last seven days, solar activity has remained at a slightly elevated level, with daily C-class flares and a few M-class flares. This, together with the decrease in geomagnetic activity, has resulted in a gradual increase in the daily maximum of the highest usable frequencies of the F2 ionospheric layer. At the same time, however, the attenuation in the lower ionospheric layers grew, which manifested as earlier morning closures and later evening openings of the longer shortwave bands.
"Particle clouds from CMEs during solar flares mostly did not reach Earth - with one exception: on 7 June at 2224 UTC, the solar wind speed jumped from 340 to 380 km/s. For a short time, the Earth's magnetic field activity increased, usually only to K=3.
"The situation was further complicated by the sporadic-E layer, whose season is approaching its peak.
"Inhomogeneities (non-uniformities) in the sporadic-E layer appeared quite frequently and extended reflections were observed in the ionograms.
"As a consequence, the scattering of electromagnetic waves was as well manifested as attenuation. We are talking about the ionosphere of the northern hemisphere of the Earth. Here we will wait for the improvement when Summer ends there - which fortunately will be much earlier than Summer ends in the troposphere."
While searching for something else, I ran across this article from the RSGB:
Mike, W9NY wrote:
"Having lived through multiple sunspot cycles since I was first licensed in 1955, I cannot believe that 10 meters is nearly dead, and 15 meters is minimally open. Nothing on 6 meters either.
"I discussed this with my cousin who is an astrophysicist at Oxford who basically said, 'there are a lot of factors.' I'm just wondering what our ham radio gurus think. I would have expected phenomenal propagation but there is very little. Might this be related to atomic/chemical changes in the Earth's ionosphere?"
I offered the WA4TTK Solar Data Plotting Utility as a record of sunspot and solar flux data going back to 1989.
It can be updated weekly with a plain text file of the latest propagation bulletin.
The data file can then be imported to any spreadsheet program for analysis and custom graphing.
A new video from Dr. Tamitha Skov, WX6SWW:
Also, check this article from September, 2002 QST:
Send your tips, reports, observations, questions and comments to firstname.lastname@example.org.
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/.
Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.
Sunspot numbers for June 1 through 7, 2023 were 143, 147, 112, 110, 151, 133, and 177, with a mean of 139. 10.7 cm flux was 163.9, 162.3, 164.6, 168.3, 169.2, 171.8, and 167.2, with a mean of 166.8. Estimated planetary A indices were 13, 5, 5, 11, 5, 7, and 5, with a mean of 7.3. Middle latitude A index was 14, 8, 5, 11, 6, 10, and 6, with a mean of 8.6.
Source: W1AW Bulletin via the ARRL.