Solar Report 11/17/22

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

Sunspot numbers and solar flux did not seem to correlate this week. Flux rose, and spots fell.

The average daily sunspot number declined from 79.8 to 72.3, but average solar flux numbers rose from 129.9 to 137.2. This tells me that the number and area of sunspots was less, but the 10.7-centimeter radiation from those spots increased.

A new sunspot emerged on November 10, another on November 13, and two more on November 16, the last day of our reporting week, which runs Thursday through the following Wednesday.

In our bulletin from 1 year ago, the average daily sunspot number was only 36.4, and solar flux was 89.1, so if the latest activity seems a bit lackluster, we can see that the sunspot cycle is making progress and is expected to peak around July 2025.

We get better HF propagation at higher frequencies when X-rays from the sun are more intense, and they correlate with sunspot numbers and the 10.7-centimeter radiation. This radiation charges the ionosphere, increasing density.

Back in 1957 – 1959, at the peak of Solar Cycle 19, the radiation was so intense that (I’ve been told) 10 meters was open worldwide, around the clock. Cycle 19, had, by far, the highest recorded sunspot count in history, with nothing like it before or since.

Here is the prediction for solar flux: 133, 125, and 122 on November 17 – 19; 120 on November 20 – 21; 122 on November 22; 125 on November 23 – 24; 115 on November 25 – 26; 120 and 125 on November 27 – 28; 130 on November 29 – 30; 135 on December 1 – 12; 120 and 110 on December 13 – 14, and 105 on December 15 – 18.

Predicted planetary A index, which gives us a clue into possible geomagnetic unrest, is 5, 8, 16, 20, and 12 on November 17 – 21; 8, 5, 8, 15, and 18 on November 22 – 26; 12, 8, 5, 5, 12, 18, and 8 on November 27 through December 3; 5 on December 4 – 7; 8 on December 8 – 9; 5 on December 10 – 11; 10 on December 12 – 13; 5 on December 14 – 16; 15 on December 17, and 18 on December 18 – 19.

The ARRL 10-Meter Contest is coming up, and will take place during the weekend of December 10 – 11. Expect better propagation than we saw in 2020 and 2021. Although predicted solar flux is not high, the prediction above shows the highest solar flux (135) over that weekend, and planetary A index at a low value of 5, indicating predicted geomagnetic stability. But of course, things may change.

Sunspot numbers for November 10 through 16 were 79, 57, 65, 74, 77, 69, and 85, with a mean of 72.3. The 10.7-centimeter flux was 138.7, 137.6, 138.2, 137, 141.5, 134.2, and 132.9, with a mean of 137.2. Estimated planetary A indices were 2, 9, 5, 7, 4, 2, and 2, with a mean of 4.4. Middle latitude A index was 2, 9, 3, 6, 3, 2, and 2, with a mean of 3.9.

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.

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