Tad Cook, K7RA, of Seattle, Washington, reports for this week’s ARRL Propagation Bulletin:
Sunspot activity took quite a plunge over this reporting week (October 13 – 19). Average daily sunspot numbers declined from 114.9 to 57.3, while equivalent solar flux values went from 155.3 to 119.6.
Geomagnetic indicators were slightly lower, with the average planetary A index going from 13.3 to 10.6, and middle latitude A index from 10.4 to 8.1.
I should note that the middle latitude A index for October 18 – 19 are my own estimates. The Fredericksburg, Virginia, magnetometer was offline for a 24-hour period spanning both days.
The Wednesday forecast of solar flux shows a peak at 160 during the first week in November.
Predicted daily flux values are 110 on October 20 – 26; 115 and 150 on October 27 – 28; 155 on October 29 – 30; 152 on October 31; 160 on November 1 – 8; 150, 140, and 135 on November 9 – 11; 130 on November 12 – 13; 135 on November 14; 138 on November 15 – 17, and 140 on November 18 – 21.
Predicted planetary A index is 12 and 10 on October 20 – 21; 5 on October 22 – 23; 10, 5, 8, and 12 on October 24 – 27; 15, 12, and 20 on October 28 – 30; 15 on October 31 through November 1; 18, 15, 12, 20, and 8 on November 2 – 6; 5 on November 7 – 9; 18 on November 10 – 11; 15 and 8 on November 12 – 13; 5 on November 14 – 15; 12 on November 16 – 17; 8 on November 18, and 5 on November 19 – 21.
Despite the lower solar activity, worldwide 10-meter propagation has been very good this week, probably helped by seasonal variations as we head deeper into the fall season.
In Friday’s bulletin, expect
reports from readers.
Sunspot numbers for October 13 through 19 were
57, 51, 50, 59, 84, 50, and 50, with a mean of 114.9. The 10.7-centimeter
flux was 130, 120.5, 115.1, 119.2, 125.6, 113.9, and 113.2, with a mean of
155.3. Estimated planetary A indices were 5, 18, 18, 16, 6, 6, and 5, with
a mean of 13.3. Middle latitude A index was 4, 16, 15, 11, 4, 4, and 3,
with a mean of 10.4.
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.
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