Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:
A new sunspot group emerged on August 18 and August 21, and two more emerged on August 23. Overall, solar activity was down slightly, with the average daily sunspot number declining from 60.8 to 58.7, and average solar flux from 123.7 to 104.5.
Planetary A index changed from an average of 11.7 to 12.6, and middle latitude A index, measured at a single magnetometer in Virginia, was 11, after an average of 10 last week.
The Wednesday night forecast from the 557th Weather Wing at Offutt Air Force Base showed a probable solar flux peak at 130 on September 11 for the near term.
Predicted solar flux is 105 on August 25 – 26; 108 on August 27 – 28; 110 on August 29 through September 1; 114 on September 2; 116 on September 3 – 4; 112 on September 5; 108 on September 6 – 7; 115, 120, 124, and 130 on September 8 – 11; 128, 120, 118, 105, and 102 on September 12 – 16; 98 on September 17 – 18; 96 on September 19 – 21; 94 on September 22 – 24, and 92, 98, and 100 on September 25 – 27.
Predicted planetary A index has some surprises in store: 5 on August 25 – 26; 8 on August 27 – 28; 5 on August 29 through September 2; then jumping way up to 30, 38, and 20 on September 3 – 5; 15, 18, 10, 12, and 8 on September 6 – 10; 5 on September 11 – 12; 12, 15, and 10 on September 13 – 15; 8 on September 16 – 17; 25, 15, and 8 on September 18 – 20; 5 on September 21 – 22; 12 on September 23, and 8 on September 24 – 26.
My main power supply failed on August 21, so for a week or two I will be unable to make on-the-air observations as I await factory repair.
News about
a large sunspot can be found at https://inshorts.com/en/news/huge-sunspot-on-suns-surface-grows-10-times-in-size-in-48-hours-pic-surfaces-1661347322422.
Sunspot numbers for August 18 through 24 were 83, 74,
56, 56, 44, 52, and 46, with a mean of 58.7. The 10.7-centimeter flux was
116.5, 105.4, 101.5, 97, 102.6, 100.9, and 107.8, with a mean of 104.5.
Estimated planetary A indices were 26, 20, 14, 14, 7, 4, and 3, with a mean of
12.6. Middle latitude A index was 19, 15, 16, 13, 7, 3, and 4, with a mean of
11.
Send your tips, questions, or comments to k7ra@arrl.net.
A comprehensive K7RA Solar Update is posted Fridays on the ARRL website. For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…” and check out the Propagation Page of Carl Luetzelschwab, K9LA.
A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.
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