The K7RA Solar Update

No sunspots this week. The pattern persists, and this surprises me. But Spaceweather.com reported a couple of weak, barely emerging spots, never numbered, and by their magnetic polarity were from new Cycle 25.

We rely on NOAA for official sunspot numbers, and the most recent one reported was 11 on June 15. See ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt.

Average daily solar flux over the recent reporting week (June 25 to July 1) averaged 68.6 up from 67.7 over the previous seven days. Average daily planetary A index was 4.7, the same as the average middle latitude A index.

Predicted solar flux over the next 45 days is 68, every day July 3 to August 16, which is hardly a promising outlook. Even with no sunspots, it would be nice to see solar flux values north of 70.

Predicted planetary A index is 5 on July 3-26, 8 on July 27-28, 5 on July 29 through August 1, 8 on August 2-3, and 5 on August 4-16.

Geomagnetic activity forecast for the period July 3-29, 2020 from OK1HH.

Geomagnetic field will be

quiet on: July 3, 9-11, 14, 18-22

quiet to unsettled on: July 4, 8, 12-13, (15, 17,) 25-28

quiet to active on: (July 5-7, 16, 23-24, 29)

unsettled to active on: None!

active to disturbed: None!

Solar wind will intensify on: July (4,) 5-8, (9-10, 16-18, 21-22,) 23-25, (26-27)

Remarks:

– Parenthesis means lower probability of activity enhancement.

– The predictability of changes remains in the long run lower as there are very few indications.

This video is quite dramatic and remarkable. An entire decade of continuous solar rotation images compressed into an hour: https://youtu.be/l3QQQu7QLoM. Background: https://go.nasa.gov/2CXkw1k

Mike, KA3JAW, reported from Easton, PA urging everyone to monitor 29.6 MHz FM. He heard nothing on 10-meter FM over Field Day weekend. I will start doing this myself now with a new radio that covers that band/mode.

An interesting article about solar plasma flow: https://www.inverse.com/science/solar-cycle-plasma-flow

Thanks to AA2F for catching errors in the A index averages appearing in the ARRL Letter (my fault), so I could correct them in this bulletin.

For more information concerning radio propagation, see http://www.arrl.org/propagation and the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere.

An archive of past propagation bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for June 25 through July 1, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 68.9, 67.8, 68.9, 69.2, 68.7, 68.1, and 68.9, with a mean of 68.6. Estimated planetary A indices were 3, 6, 7, 4, 3, 4, and 6, with a mean of 4.7. Middle latitude A index was 2, 6, 6, 4, 4, 5, and 6, with a mean of 4.7

SOURCE:ARRL