Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:

Sunspot activity rose this week, as the average daily sunspot numbers increased from 68 to 105.1.

But solar flux? Not so much. The average daily solar flux rose from 134.3 to 138.4.

So, the sunspot average rose 55% and solar flux rose only 3%. We usually expect the numbers to track closer.

Tuesday, September 27, had lots of geomagnetic activity, with the planetary A index at 24 and middle latitude at 33. At www.spaceweather.com, blamed an unexpected CME for this activity. They also reported a huge sunspot beyond the sun’s eastern horizon and a helioseismic image at https://bit.ly/3ftpTIN.

The Australian Space Weather Forecasting Centre issued a geomagnetic warning at 2146 UTC on September 28, stating, “Geomagnetic 27-day recurrence patterns indicate that G1 geomagnetic activity is likely during the interval between September 30 and October 2. INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL HOLE HIGH SPEED WIND STREAM.”

Predicted solar flux is 135 on September 29; 130 on September 30 through October 1; 125 on October 2 – 3; 120 on October 4 – 5; 132 on October 6 – 7; 135, 130, 128, and 132 on October 8 – 11; 136 on October 12 – 13; 138, 140, 138, and 135 on October 14 – 17; 132, 130, 128, and 125 on October 18 – 21; 130, 140, 142, and 145 on October 22 – 25, and 140, 135, 130, 125, 128, and 130 on October 26 – 31.

Planetary A index is predicted at 8, 20, 60, and 40 on September 29 through October 2; 20, 18, 16, and 10 on October 3 – 6; 8 on October 7 – 14; 10 on October 15 – 16; 8 on October 17 – 19; 12 on October 20 – 21; 8 on October 22 – 23; 10 on October 24 – 25, and 8 on October 26 – 27. Then, in a recurrent disturbance as the sun rotates into the same position as weeks earlier, 25, 50, 30, 20, 12, and 10 on October 28 through November 2.

Sunspot numbers for September 22 through 28, were 99, 111, 128, 96, 120, 110, and 72, with a mean of 105.1. The 10.7-centimeter flux was 136.7, 146.3, 146.5, 134.7, 135.1, 134.5, and 134.8, with a mean of 138.4. Estimated planetary A indices were 6, 12, 13, 7, 6, 24, and 5, with a mean of 10.4. Middle latitude A index was 5, 12, 10, 5, 5, 33, and 3, with a mean of 10.4.

Send your tips, questions, or comments to k7ra@arrl.net.

Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:

Geomagnetic disturbances were down this week, but so were sunspot numbers and solar flux.

Average daily sunspot numbers declined from 92.7 to 68, and average daily solar flux declined from 141.3 to 134.3.

Six new sunspot groups appeared this week, the first on September 15, two more on September 19, another on September 20, and two more on September 21.

Predicted solar flux is 140 and 138 on September 22 – 23; 130 on September 24 – 27; 120 on September 28; 122 on September 29 through October 2; 120 again on October 3; 122 on October 4 – 7; 125, 122, and 120 on October 8 – 10; 118 on October 11 – 12; 116 on October 13 – 15; 138 on October 16; 135 on October 17 – 18, and 133, 128, 126, 130, and 125 on October 19 – 23.

Predicted planetary A index is 10 and 20 on September 22 – 23; 15 on September 24 – 25; 8 on September 26 – 29; 22, 50, 30, and 20 on September 30 through October 3; 12, 15, 12, and 10 on October 4 – 7; 8, 8, 5, and 8 on October 8 – 11; 5 on October 12 – 14; 12, 10, 5, 5, 20, 18, and 12 on October 15 – 21, and 8 on October 22 – 26.

The above predictions were made by the Offutt Air Force Base.

For information on whether sunspots are really black, visit www.livescience.com/why-are-sunspots-black.

I’m pleased to report that the 2022 Autumnal Equinox is Friday, September 23, at 0104 UTC. Both the Northern and Southern Hemispheres will be bathed in equal measures of solar radiation, which is good for HF propagation.

Sunspot numbers for September 15 through 21 were 71, 64, 76, 51, 74, 70, and 70, with a mean of 68. The 10.7-centimeter flux was 139.7, 131.1, 131.5, 136.1, 127.9, 137.2, and 136.9, with a mean of 134.3. Estimated planetary A indices were 6, 4, 5, 11, 11, 8, and 5, with a mean of 7.1. Middle latitude A index was 8, 5, 5, 9, 7, 6, and 4, with a mean of 6.9.

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.

Share your reports and observations.

Solar activity bounced back this reporting week, September 8 – 14, when the average daily sunspot number jumped from 68 to 92.7, and the average solar flux from 125.8 to 141.3.

Fewer Coronal Mass Ejections (CMEs) and flares were evident, with the average planetary A index declining from 24.6 to 10.7, and the middle latitude numbers from 17.4 to 10.6.

New sunspot groups appeared: one on September 8, three on September 10, and one more on September 13. The total sunspot area (in millionths of a solar disc) on September 12 – 14 rose from 370 to 870 to 1240 — the highest value in over a month.

The sunspot number was highest on September 10 at 122.

During this week 2 years ago, there were no sunspots at all. The average daily solar flux was only 69.7, over 56 points lower than this week, demonstrating the continued progress of Cycle 25.

The latest (Wednesday) forecast from the space weather folks at Offutt Air Force Base shows predicted solar flux peaking at 150 on October 9, and flux values on September 15 at 140. Then 135 on September 16 – 18; 130 on September 19 – 21; 120 on September 22 – 29; 125 on September 30 through October 6; 130 on October 7 – 8; 150, 148, 143, and 140 on October 9 – 12; 136, 130, 125, and 120 on October 13 – 16, and 125 on October 17.

Predicted planetary A index shows moderate levels of geomagnetic activity until October 1 – 2. The forecast is 5, 15, 18, and 12 on September 15 – 18; 5 on September 19 – 22; 12 and 10 on September 23 – 24; 14 on September 25 – 27; 8 on September 28 – 29; 22, 50, 40, 20, and 12 on September 30 through October 4; 15, 12, 10, 8, and 5 on October 5 – 9; 10, 8, 5, 15, 20, and 12 on October 10 – 15, and 5 on October 16 – 19.

Below is a nice solar video from last month:

https://bit.ly/3BH9ZDm

Here is NOAA’s latest forecast discussion:

https://www.swpc.noaa.gov/products/forecast-discussion

Sunspot numbers for September 8 – 14 were 75, 72, 122, 113, 117, 93, and 57, with a mean of 92.7. The 10.7-centimeter flux was 126.6, 126.2, 135.9, 151.5, 150.4, 154.1, and 144.3, with a mean of 141.3. Estimated planetary A indices were 19, 13, 12, 9, 9, 4, and 9, with a mean of 10.7. The middle latitude A index was 17, 14, 10, 9, 9, 5, and 10, with a mean of 10.6.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Share your reports and observations.

This week, September 1 – 7, 2022, two new sunspot groups emerged on September 1, two more on September 2, one more on September 5, another on September 6, and one more on September 7.

But average daily sunspot numbers declined from 74.9 to 68, while average daily solar flux rose from 123.8 to 125.8.

Geomagnetic indicators were way up, and the average daily planetary A index rose from 10.1 to 24.6, while middle latitude numbers increased from 9.4 to 17.4.

September 4 was the most active day, with the planetary A index being 64. On that day, the college A index in Fairbanks, Alaska, was 91!

Predicted solar flux is 125 on September 8 – 14; 126 on September 15; 125 on September 16 – 17; 126 and 120 on September 18 – 19; 125 on September 20 – 21; 115 on September 22 – 24; 120 on September 25 – 28; 118 on September 29 – 30; 115 and 125 on October 1 – 2; 120 on October 3 – 4; 122 on October 5; 120 on October 6 – 7; and 125 on October 8 – 11.

Predicted planetary A index is 50 on October 1! Otherwise, 10 on September 8; 8 on September 9 – 11; 5 on September 12; 20 on September 13 – 14; 10 on September 15; 8 on September 16 – 17; 5 on September 18 – 22; 12 and 10 on September 23 – 24; 14 on September 25 – 27; 8 on September 28 – 29; 22, 50, 25, 16, 12, and 10 on September 30 through October 5; 8 on October 6 – 8, and 5, 12, and 15 on October 9 – 11.

Sunspot numbers for September 1 through 7 were 67, 71, 68, 62, 79, 56, and 73, with a mean of 68. The 10.7-centimeter flux was 116.3, 129.8, 123.4, 128.3, 130.2, 126.2, and 126.1, with a mean of 125.8. Estimated planetary A indices were 9, 8, 25, 64, 32, 20, and 14, with a mean of 24.6. Middle latitude A index was 9, 10, 23, 33, 21, 14, and 12, with a mean of 17.4.

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.