The K7RA Solar Update
Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin, ARLP002:
Sunspot numbers are up and geomagnetic disturbances are down. What could be better? Okay, maybe Cycle 19, but that was 66 years ago and by far the all-time largest sunspot cycle.
But this is now, we are in Cycle 25, and this sunspot cycle is emerging better than the consensus prediction. It is predicted to peak 30 months from now in the summer of 2025. Solar cycles tend to ramp up quickly and decline slowly, so we can look forward to great propagation for years to come.
There were six new emerging sunspot groups in our reporting week, January 5 – 11. The first two appeared January 5, the next on January 8, another on January 9, and two more on January 10.
The average daily sunspot number rose from 97 to 135.9, and the average daily solar flux from 157.8 to 181.2, compared to last week.
The average daily planetary A index declined from 15.4 to 6.7, and the middle latitude A index from 10.9 to 6.1.
Compare the solar numbers to last year. A year ago, in ARLP002, the average daily sunspot number was only 42.4 (135.9 now), and the average daily solar flux was 101.6 (181.2 now). Ten and 12 meters now have openings every day.
The predicted solar flux is 196 on January 12 and 13; 198, 196, 194, 192, 190, 188, and 140 on January 14 – 20; 130 on January 21 – 22; 135 on January 23; 140 on January 24 – 26; 145 on January 27; 155, 155, and 160 on January 28 – 30; 170 on January 31 – February 2; 175 and 180 on February 3 – 4; 185 on February 5 – 6; 180, 178, and 175 on February 7 – 9; 155 on February 10 – 12, and 145 on February 13.
The predicted planetary A index is 5 on January 12 – 17; 10, 18, 15, and 8 on January 18 – 21; 5 on January 22 – 24; 8, 22, 12, and 8 on January 25 – 28; 5 on January 29 – 31; 12 and 8 on February 1 – 2; 5 on February 3 – 5; 10, 12, and 8 on February 6 – 8, and 5 on February 9 – 13.
Jon Jones, N0JK, Editor for “The World Above 50 MHz” column in QST, writes:
“There was a 6-meter F2 opening between Ecuador and North America on January 6, 2023, around 1530 UTC, mostly between the southeast United States and Ecuador. Solar flux was 154.” (Actually, solar flux was 154.3 on January 5 and 172.4 on January 6).
“Later, there was some weak sporadic-E on 6 meters. I logged W4IMD (EM84) 1942 UTC, and W7JW (EN82) on 6-meter FT8 via Es at 1954 UTC on January 6. High solar activity this week.”
Sunspot numbers on January 5 through 11 were 103, 101, 104, 117, 142, 201, and 183, with a mean of 135.9. The 10.7-centimeter flux was 154.3, 172.4, 178.9, 183.8, 190.9, 193, and 195.1, with a mean of 181.2. Estimated planetary A indices were 8, 4, 6, 8, 5, 7, and 9, with a mean of 6.7. Middle latitude A index was 6, 4, 5, 7, 7, 6, and 8, with a mean of 6.1.
Send your tips, questions, or comments to k7ra@arrl.net.
A comprehensive K7RA Solar Update is posted on 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.
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