Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:
Although images of the sun this week showed plenty of sunspots, only two new spots emerged: one on July 21, and another on July 25.
Average daily sunspot number declined from 137.3 to 91.1, and the average daily solar flux softened by 50 points to 107.6.
Geomagnetic indicators began this reporting week fairly active, with planetary A index at 22, then it quickly quieted down to an average of 11.7 for the week, higher than the 9.4 average reported last week. Average middle-latitude A index increased from 9 to 10.4.
A look back a year ago shows this cycle is progressing nicely. In ARLP030 in 2021 average daily sunspot number was just 48.9, and average daily solar flux only 81.3.
A year prior, the average daily sunspot number in 2020 was just 3.1! That is because there were five days with no sunspots, and then two days with a sunspot number of only 11, which is the minimum non-zero sunspot number.
A sunspot number of 11 does not mean 11 sunspots. It means there was just one sunspot group (which counts for 10 points) and one sunspot in that group (counting for 1), producing a total of 11, because of the arcane historical method of counting sunspots.
Predicted solar flux shows it peaking at 130 on August 11. Predicted flux is 98 on July 28, 96 on July 29 – 30, 98 again on July 31 and August 1, 96 on August 2 – 3, 98 on August 4, then jumping to 115 on August 5 – 6, 113 on August 7 – 8, then 120, 125, 130 and 125 on August 9 – 12, 120 on August 13 – 15, 118 on August 16 – 17, then 114 and 110 on August 18 – 19, 108 on August 20 – 21, then 106 and 102 on August 22 – 23, 100 on August 24 – 27, and 108 on August 28 – 29.
Predicted planetary A index is 8 on July 28-29, 12 on July 30, 8 on July 31 and August 1, 5 on August 2 -3, 8 on August 4, 5 on August 5 -10, 8 on August 11 -12, 5 on August 13 – 16, 22 on August 17, 15 on August 18 – 19, 8 on August 20 -21, 5 on August 22 – 25, 10 and 12 on August 26 – 27, and 5 on August 28 – 29.
Sunspot numbers for July 21 – 27, 2022 were 124, 107, 96, 80, 100, 78, and 53, with a mean of 91.1. 10.7-centimeter flux was 121.7, 114.7, 110.5, 107.1, 102.3, 98.8, and 98, with a mean of 107.6. Estimated planetary A indices were 22, 11, 17, 9, 6, 8, and 9, with a mean of 11.7. Middle latitude A index was 14, 11, 15, 9, 8, 7, and 9, with a mean of 10.4.
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