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The K7RA Solar Update

07/31/2020

Tad Cook, K7RA, Seattle, reports: Finally, sunspots have returned! Two sunspots now are visible, both from new Solar Cycle 25. The daily sunspot number was 11 for July 21-27, rising to 22 for July 28-30.

Recently, we have noticed an improvement in propagation due to seasonal sporadic-E activity.

Average daily sunspot numbers rose from 3.1 to 14.1 this week, and average daily solar flux edged up from 69.1 to 71.1.

Total sunspot area covered 80 millionths of the solar disc on July 21, 120 millionths on July 22-26, and the coverage on the following 4 days was 70, 50, 85 and 110.

Geomagnetic indicators were a bit more active, with average daily planetary A index rising from 3.9 to 6.7, while average daily mid-latitude indicators rose from 4.3 to 8.7.

Predicted solar flux is 72 on July 31 – August 2, 70 on August 3 – 7, 68 on August 8 – 22, 69 on August 23 – 28, and 68 on August 29 – September 13.

Predicted planetary A index is 5 on July 31, then 8 and 10 on August 1 – 2, 5 on August 3 – 23, 8 on August 24 – 25, and 5 on August 26 – September 13.


Here is the geomagnetic activity forecast for the period July 31 to August 26 from F.K. Janda, OK1HH. The geomagnetic field will be:

  • Quiet on August 4 – 7, 15 – 19, 22 – 26

  • Quiet to unsettled on July 31, August 2 – 3, (8,) 9, 11, (12 – 14,) 20

  • Quiet to active on (August 1, 10, 21)

  • Unsettled to active not expected

  • Active to disturbed not expected

  • Solar wind will intensify on: August 1 – 3 (-4, 11 – 15,) 20 – 21, (22 – 25)

Notes:

+Parenthesis means lower probability of activity enhancement.

+Predictability of changes remains lower this time, thanks to new active regions on the Sun.


K7DWI offers interesting details on his blog about using cheap SDR dongles for studying VHF openings.

Thanks to Howard Lester, N7SO for this article on solar flares:

And thanks to regular contributor David Moore for this article from Science Daily.

Here’s the latest from Space Weather Woman Tamitha Skov, WX6SWW.

Her QRZ.com profile was recently updated and expanded.

Sunspot numbers for July 23 – 29, 2020 were 11, 11, 11, 11, 11, 22, and 22, with a mean of 14.1. The 10.7-centimeter flux was 70.3, 69.5, 70.4, 71.4, 71.4, 71.8, and 72.6, with a mean of 71.1. Estimated planetary A indices were 4, 11, 15, 3, 4, 5, and 5, with a mean of 6.7. Middle latitude A index was 4, 13, 27, 3, 5, 5, and 4, with a mean of 8.7.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out K9LA’s Propagation Page.

A propagation bulletin archive is available. Monthly charts are no longer be updated on this page. 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.

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