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The K7RA Solar Update

11/12/2021

Tad Cook, K7RA, Seattle, reports: Sunspot activity and solar flux dropped this reporting week (November 4 – 10), with average daily sunspot number retreating from 67.6 to 36.4, and solar flux from 102 to 89.1. Geomagnetic indicators rose, average daily planetary A index from 12 to 18, and middle latitude values from 9 to 11.7.

When the planetary and middle latitude A index were 69 and 42 on November 4, Alaska’s college A index was a whopping 131. College K index peaked at 9 on that day. K index is logarithmic, so each point in the scale represents a big difference in activity. The A index is linear and based upon the K index.

The K index is reported every 3 hours, and the college K index on November 4 was 5, 5, 8, 9, 8, 5, 3, and 2. This was all caused by what Spaceweather.com (and others) called a “cannibal CME,” because it was a CME (coronal mass ejection) overtaken by a second larger and faster-moving CME. At 1701 UTC on November 9 a CME just over the sun’s western horizon emitted enough energy to cause an HF radio blackout.

Predicted solar flux is 86 on November 12; 85 on November 13 – 16; 84 on November 17; 83 on November 18 – 19; 90 on November 20; 95 on November 21 – 27; 90 on November 28 – 29; 85 on November 30 – December 2; 82 on December 3 – 4; 85 on December 5; 82 on December 6 – 9; 80 on December 10 – 11; 85 on December 12, and 87 on December 13 – 15. Flux values may peak at around 95 on December 18 – 24.

Predicted planetary A index is 5 on November 12 – 15; 8 on November 16 – 17; 5 on November 18 – 27; 10, 10, and 8 on November 28 – 30; 5 on December 1 – 4; 8 on December 5; 5 on December 6 – 9; 7, 7, 10, and 8 on December 10 – 13, and 5 on December 14 – 24.

Here’s the geomagnetic activity forecast from F.K. Janda, OK1HH, for November 12 – December 1. The geomagnetic field will be:

  • quiet on 18 – 19, 23, 25

  • quiet to unsettled on November 12 – 13, 17, 20, 22, 24

  • quiet to active on November 21, 26 – 27

  • unsettled to active on November 14, 16, 28

  • Active to disturbed November (15, 29,) 30, December 1

  • Solar wind will intensify on November 16 – 17, (29 – 30), December (1 – 2,) 3 – 4

Note: Parentheses mean lower probability of activity enhancement.

Here’s an interesting retrospective from NASA on the STEREO spacecraft, “Sun 360, STEREO Mission’s 10-Year Retrospective.” Unfortunately, only one of the two spacecraft remains, but it is still a very useful tool.

Jon, N0JK wrote from Kansas:

“Good conditions on 17 meters Sunday afternoon November 7. I found the HD8R Galapagos Island DXpedition on 18.147 MHz SSB, loud with few callers. Was able to work them easily with 5 W and mobile whip at 2022 UTC. Sometimes a DXpedition is easier to work on the WARC bands.”

Early on November 12, Spaceweather.com reported all is quiet for now:

“Space weather near Earth is calm, but the sun is not quiet. This week, SOHO coronagraphs have observed multiple CMEs billowing over the western edge of the sun. The source is a far-side sunspot group, probably the same one that produced a strong M2-class solar flare on November 9. Earth is not in the line of fire, for now.

Here’s another great video report from Tamitha Skov, WX6SWW, the Space Weather Woman.

Sunspot numbers for November 4 – 10 were 28, 40, 41, 28, 41, 40, and 37, with a mean of 36.4. The 10.7-cm flux was 93.8, 92.8, 82.1, 87.5, 88.3, 92, and 87.5, with a mean of 89.1. Estimated planetary A indices were 69, 13, 18, 6, 5, 7, and 8, with a mean of 18. Middle latitude A index was 42, 9, 13, 4, 3, 6, and 5, with a mean of 11.7.

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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