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The K7RA Solar Update

10/15/2021

Tad Cook, K7RA, Seattle, reports: Although we saw sunspots on every day of the October 7 – 13 reporting week, solar activity declined somewhat. Average daily sunspot numbers went from 30.7 to 23.7, and average daily solar flux from 86.9 to 85.6. Geomagnetic indicators were higher, with average daily planetary A index rising from 8.1 to 12.4, and average daily middle latitude A index from 6.7 to 10.1.

On Saturday, October 9, Spaceweather.com reported a strong earth-directed M1.6-class solar flare and CME erupting at 0640 UTC, causing an HF radio blackout over the Indian Ocean. This caused the planetary A index on October 12 to hit 45, and Alaska’s College A index to read 60.

Predicted solar flux is 82 on October 15; 80 and 78 on October 16 – 17; 76 on October 18 – 22; 85 on October 23 – 24; 90, 100, 95, and 90 on October 25 – 28; 88 on October 29 – 30; 85 on October 31 – November 5; 88 on November 6; 85 on November 7 – 13; 88 on November 14 – 15; 90 on November 16; 88 on November 17 – 18, and back to 100 on November 22.

Predicted planetary A index is 8 on October 15 – 16; 5 on October 17; 12 on October 18 – 19; 8 on October 20; 5 on October 21 – 24; 10 on October 25; 5 on October 26 to November 1; 8 on November 2; 5 on November 3 – 5; 10 on November 6 – 7; 8 on November 8 – 9; 5 on November 10 – 12; 10, 12, 12, 10, and 8 on November 13 – 17; 5 on November 18 – 20; 10 on November 21, and 5 through the end of the month.

Here’ the geomagnetic activity forecast for October 15 – November 9 from F.K. Janda, OK1HH.

The geomagnetic field will be:

  • quiet on October 16 – 17, November 3, 5

  • quiet to unsettled on October 20 – 22, 24, 26 – 27, 30 – 31, November 4

  • quiet to active on October 23, 25, November 6

  • unsettled to active on October (15, 18 – 19, 28 – 29,) November (1 – 2,) 7 – 9

  • Active to disturbed — Nothing predicted

Solar wind will intensify on October (19, 22, 25,) 27 – 31, November 1, 9

Parentheses mean lower probability of activity enhancement.

On October 12, Spaceweather.com reported in an email alert: “Last night, a coronal mass ejection (CME) struck Earth’s magnetic field, sparking a moderately strong geomagnetic storm. Auroras were sighted in the USA as far south as Nebraska with lights so bright in some places that onlookers successfully photographed them using cell phones.”

The November 2021 issue of QST arrived, and the article on page 70, “Propagation Tools and Resources for Contesting” by WO1N, KC2G and members of the Yankee Clipper Contest Club shares some great resources, not only of interest to contest operators.

Here’s an interesting article on 60 meters propagation.

Here is the October 11 video report from Space Weather Woman Tamitha Skov, WX6SWW.

Sunspot numbers for October 7 – 13 were 13, 13, 14, 38, 35, 26, and 27, with a mean of 23.7. The 10.7-centimeter flux was 85.7, 92.4, 81, 84.5, 88.5, 83.5, and 83.5, with a mean of 85.6. Estimated planetary A indices were 5, 4, 5, 9, 13, 45, and 6, with a mean of 12.4. Middle latitude A index was 3, 3, 4, 9, 15, 32, and 5, with a mean of 10.1.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check this propagation page by Carl Luetzelschwab, K9LA.

A propagation bulletin archive is available. For customizable propagation charts, visit the VOACAP Online for Ham Radio website.

Instructions for starting or ending email distribution of ARRL bulletins are on the ARRL website.

Share your reports and observations.



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