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The K7RA Solar Update

On July 7 Spaceweather.com reported a G-1-class geomagnetic storm underway, with possible increase to G-2 class. They said it was caused by a co-rotating interaction region. The storm subsided, but then came back early on July 8.

Late on July 7 Spaceweather.com presented this animation of a large new sunspot AR3053 emerging over the sun’s eastern horizon:

https://bit.ly/3bYQImG

Notice that unlike here on Earth, the sun’s eastern horizon is on the left? Perhaps we can explain that in a future bulletin. Your input would be appreciated.

When I suspect HF conditions are disturbed due to geomagnetic activity, I look at the latest K index on this site:

https://bit.ly/3RiFMAh

The left column of K indices starts at 0300 UTC and repeat every three hours. At the end of the UTC day, an A index number is assigned.

For an even more up to date indicator, I check here: https://bit.ly/3IpOUiQ. Note the 6 hour, 1-day, 3-day and 7 day options in the upper left corner.

Sunspot activity increased this week, with average daily sunspot numbers going from 49.1 to 62.6. But oddly, average daily solar flux was down slightly from 105.3 to 103.5.

Taking a longer view, solar activity is stronger than it was a year ago, when average daily sunspot number was 34.7 and average solar flux was 86.9 as reported in ARLP027 in 2021.

Spaceweather.com reported that a CME missed Earth on July 1, but it pushed dense solar wind plasma toward us, causing a G1 class geomagnetic storm. In the few hours past midnight UTC planetary K index was 4, then 5. Alaska’s high latitude college A index was 25 on July 2.

Predicted solar flux for the next month is 128 on July 8, 130 on July 9 and 10, then 128 and 125 on July 11 and 12, 120 on July 13 and 14, then 115, 110, 100, 95 and 98 on July 15 to 19, 95 on July 20 and 21, 98 on July 22 and 23, 100 on July 24 and 25, 102 on July 26, 105 on July 27 and 28, 100 on July 29, 110 on July 30 and 31, 112 on August 1 and 2, 115 on August 3 to 6, 112 on August 7 and 8, 110 on August 9, 108 on August 10 and 11, then 110, 100, 95 and 98 on August 12 to 15.

Predicted planetary A index 15 on July 8, 5 on July 9 to 12, 12 and 15 on July 13 and 14, 12 on July 15 and 16, 10 on July 17, 8 on July 18 to 21, then 12, 15, 10 and 8 on July 22 to 25, 5 on July 26 to 31, then 8, 25, 12 and 8 on August 1 to 4, and 5 on August 5 to 9,then 10, 15, 12 and 10 on August 10 to 13.

The above forecast is from Sadovsky and Thompson at the USAF 557th Weather Wing. See https://bit.ly/3PcPNNC for an article about their operation.

F. K. Janda, OK1HH reports: “A slow-moving CME that left the Sun on June 26 finally hit Earth on July 1 and triggered a positive phase of the disturbance with improved ionospheric shortwave propagation conditions. This was followed by a slight worsening. Then we observed a slow improvement thanks to increasing activity of the sporadic E layer since 6 July. There was an even greater chance for so-called short skips in the early hours of July 7.

A co-rotating interaction region (CIR) hit Earth’s magnetic field on July 7th, sparking a G1-class (maybe G2) geomagnetic storm.” Dr. Tamitha Skov, WX6SWW, presents a new video, 108 minutes long:

Earthsky update:

https://bit.ly/3OSNX4V

Thanks to Max White for this:

https://bit.ly/3RgmZpt

https://bit.ly/3nOYBO0

Send your tips, reports, questions and comments to k7ra@arrl.net .

For more information concerning shortwave 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/.

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

Sunspot numbers for June 30 through July 6, 2022 were 40, 30, 57, 42, 79, 92, and 98, with a mean of 62.6. 10.7 cm flux was 95.7, 98, 100.2, 102.2, 104.4, 109.4, and 114.6, with a mean of 103.5. Estimated planetary A indices were 5, 7, 19, 8, 21, 4, and 5, with a mean of 9.8. Middle latitude A index was 5, 8, 17, 11, 18, 4, and 5, with a mean of 9.7. (arrl.org)

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