Tad Cook, K7RA, Seattle, reports: Sunspot activity persisted over the reporting week, although numbers were a bit lower. Average daily sunspot number declined from 124.4 to 110.1. Average daily solar flux slipped just slightly from 125 to 124. Average daily planetary A index went from 9.1 to 6.4, and average middle latitude numbers changed from 6.4 to 4.4.
New sunspot groups appeared on December 25, 26, and 28.
Predicted solar flux over the next month is expected to peak at 130 on January 18 – 19, and the numbers are 110, 108, and 105 on December 30 – January 1; 104 on January 2 – 3; 100 on January 4; 98 on January 5 – 6; then 92, 100, 105, and 110 on January 7 – 10; 115 on January 11 – 13; 118 on January 14 – 15; 122 and 128 on January 16 – 17; 130 on January 18 – 19; 128, 125, and 120 on January 20 – 22; 125 on January 23 – 24; 122 on January 25; 120 on January 26 – 27; 115, 110, 100, and 95 on January 28 – 31; 90 on February 1 – 2, and 92 and 100 on February 3 – 4.
Predicted planetary A index is 10 and 8 on December 30 – 31, then 6, 12, and 8 on January 1 – 3; 5 on January 4 – 10; 10 on January 11 – 12; 5 on January 13 – 14; 8 and 12 on January 15 – 16; 8 on January 17 – 18; 5 on January 19 – 22; 8, 10, 8, and 8 on January 23 – 26, and 5 on January 27 – February 6.
Sunspot numbers for December 23 – 29 were 143, 145, 117, 95, 85, 107, and 79, with a mean of 110.1. The 10.7-centimeter flux was 129.8, 126.2, 130.7, 125.4, 123.9, 120.5, and 111.4, with a mean of 124. Estimated planetary A indices were 4, 5, 7, 3, 10, 9, and 7, with a mean of 6.4. Middle latitude A index was 2, 3, 5, 2, 8, 6, and 5, with a mean of 4.4.
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