Nine new sunspot groups appeared this week, but the average daily sunspot numbers were lower.
A new sunspot group appeared every day on September 15 – 17; four more appeared on September 18, and one appeared each day on September 19 – 20, 2023.
The average daily sunspot numbers declined from 138.1 to 118.4, while the average daily solar flux declined from 159.9 to 149.3.
The autumnal equinox in the Northern Hemisphere is Friday, September 22, 2023. The change in seasons has been evident with improving conditions on 10 and 12 meters.
A fast-moving coronal mass ejection (CME) hit Earth on September 18, sparking dramatic displays of aurora across the northern tier of North America, and in Europe as far south as France.
Alaska’s college A index was 49 and 61 on September 18 – 19, while the planetary A index was 30 and 49.
Predicted solar flux is 155, 152, 153, and 155 on September 21 – 24; 160 on September 25 – 27; 135 on September 28 – 30;130, 135, 130, and 135 on October 1 – 4; 140 on October 5 – 6; 135 on October 7 – 8; 140, 145, and 145 on October 9 – 11, 150, 150, 155, and 150 on October 12 – 15, and 155, 150, 145, and 145 on October 16 – 19.
Predicted
planetary A index is 8 and 15 on September 21 – 22; 12 on September 23 – 26; 5,
8, 12, and 8 on September 27 – 30; 5 on October 1 – 11; 8 on October 12, and 5
on October 13 – 19.
Sunspot numbers for
September 14 – 20, 2023, were 110, 96, 88, 94, 139, 143, and 159, with a mean
of 118.4. The 10.7-centimeter flux was 145.2, 139.1, 140.4, 144.6, 154.5,
166.1, and 155.5, with a mean of 149.3. Estimated planetary A indices were 18,
7, 7, 16, 30, 49, and 16, with a mean of 20.4. Middle latitude A index was 13,
7, 5, 14, 21, 38, and 15, with a mean of 18.1.