Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin, ARLP050:
Heightened sunspot activity over the past week no doubt produced the great conditions during last weekend’s ARRL 10-Meter Contest.
Compared to the previous 7 days, average daily sunspot numbers jumped from 85 to 136.9, while solar flux averages increased from 137.5 to 150.
Geomagnetic indicators were lower, with planetary A index decreasing from 14.4 to 7.7, and middle latitude A index decreasing from 9.1 to 6.
Higher sunspot numbers and lower geomagnetic indicators are an ideal combination for favorable HF propagation.
New sunspots appeared every day except December 12, with one new sunspot on December 8, another on December 9, three more on December 10, another on December 13, and one more on December 14.
The latest prediction from the United States Air Force (USAF) via National Oceanic and Atmospheric Administration (NOAA) shows solar flux at 164, 160, 158, and 156 on December 15 – 18; 154 on December 19 – 20; 150 and 125 on December 21 – 22; 120 on December 23 – 28; 125, 130, and 135 on December 29 – 31; 145 on January 1 – 8; 140, 130, 125, and 120 on January 9 – 12, and 115 on January 13 – 18.
Predicted planetary A index is 5 on December 15 – 17; 8 on December 18 – 20; 12, 20, 15, and 12 on December 21 – 22; 20 on December 25 – 28; 12, 10, 12, 8, 5, and 18 on December 29 through January 3; 10 on January 4 – 5; 8 on January 6; 5 on January 7 – 14, and 10 on January 15 – 16.
In
Friday’s bulletin we will have reports from the 10-meter contest and some
6-meter observations.
Sunspot numbers for December 8 through 14, 2022, were 115, 116, 111, 141, 142,
159, and 174, with a mean of 136.9. The 10.7-centimeter flux was 143, 149.1,
141.7, 147,7, 150.8, 153, and 164.7, with a mean of 150. Estimated planetary A
indices were 11, 11, 8, 10, 6, 4, and 4, with a mean of 7.7. Middle latitude A
index was 9, 9, 6, 7, 5, 3, and 3, with a mean of 6.
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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