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The K7RA Solar Update


Tad Cook, K7RA, Seattle, reports: Solar activity took a deep dive during the July 29 – August 4 reporting week. Sunspots were gone July 28 – August 1, so the average daily sunspot number dropped from 33.1 last week to 6 this week. Average daily solar flux slipped from 83 to 74.8.

Predicted solar flux is 74 and 73 on August 6 – 7; 75 on August 8 – 10; 74 on August 11 – 12; 75 on August 3 – 14; 76 on August 15 – 16; 75 and 74 on August 17 – 18; 72 on August 19 – 31; 74 on September 1, and 75 on September 2 – 10.

Predicted planetary A index is 12, 8, and 8 on August 6 – 8; 5, 10, and 8 on August 9 – 11; 5 on August 12 – 15; 10, 8, and 8 on August 16 – 18; 5 on August 19 – 22; 8, 12, and 8 on August 23 – 25; 5 on August 26 – 31; 12 and 10 on September 1 – 2, and 5 on September 3 – 11.

Here’s the geomagnetic activity forecast for August 6 – 31 from F.K. Janda, OK1HH.

The geomagnetic field will be:

  • quiet on August 12 – 13, 20 – 21, 23, 28

  • quiet to unsettled on August 7 – 9, 14, 19, 22, 25 – 27, 31

  • quiet to active on August 6, 11, 15 – 18, 29 – 30

  • unsettled to active August 10, 24

  • active to disturbed: Nothing predicted

I (K7RA) spent 8 days in the hospital for neurosurgery last week, so I brought my laptop along and was able to compile this week’s report, thanks to help from many readers.

One thing I did every day to keep myself busy and make propagation observations was to use free public receivers on the internet via resources such as to search for 10-meter propagation beacons. Then, I would document and send signal reports to the beacon operators. In July, I put up an IARU-coordinated CW beacon, K7RA/b on 28.2833 MHz, and enjoy receiving reports from listeners.

Jon Jones, N0JK, writes:

“There was a 2-meter sporadic-E opening on August 4. Ron, WZ1V (FN31) reported to me that he worked KA9CFD (EN40), K0TPP (EM48), and W5LDA (EM15) at around 2225 UTC on FT8 via Es. He said KA9CFD was loud. 2-meter Es is very rare in August.

“The last week of July there was a strong tropospheric opening on 2 meters from northeast Kansas. I worked as far as KE8FD (EN80) and W3CP (EM74) on FT8. I had a PSK flag on 2 meters from W3IP (FM19), more than 1,500 kilometers (930 miles) away.

“The Perseids meteor shower is building in intensity with people now making morning MSK144 contacts on 2 meters. The peak is the night of August 11 and the morning of August 12.”

Ken Brown, N4SO, on Alabama’s Gulf Coast reports:

“On July 30, the Estimated International Sunspot Number (EISN) was 0, and July 31, and I was still able to log VE3TEN, KA3JOE and W2DLL — Ontario, Pennsylvania, and New York, nearly a straight line to the northeast.

“On July 31, I was still able to log K6FRC/b at 1454 UTC. Weak but readable (339).

“On August 1, at 0400 UTC, 11 PM local, I had a long list starting with N9TNY, W8EH, WA2SFT, WI4L, and K4JEE, in EN51, EM79, EM76, EM74, and EM78, respectively. Straight line north and northeast.”

From multiple sources, I received a news release from the High Altitude Observatory in Colorado regarding the revision of their Solar Cycle 25 predictions. The parts about radio propagation and the progression of Solar Cycle 24 are mine.

News Release: A revised prediction from the NASA High Altitude Observatory based at the University of Colorado. NASA heliophysicists have released a revised prediction for Solar Cycle 25. The report generated by Ricky Egeland, a solar physicist working in the NASA Space Radiation Analysis Group, now calls for the peak of Solar Cycle 25 to top out at a value of 195 ±17 based upon the new scale for calculating smoothed sunspot number (SSN). For reference Solar Cycle 21 peaked at an SSN of 233 (new scale) while Solar Cycle 23 peaked at an SSN of 180 (new scale).

If this prediction holds up ham radio will see excellent world-wide F-layer conditions on 10 meters for several years around the time of the solar maximum. Conditions on 6 meters should be good in the equinox periods before and after solar max with consistent openings on medium haul polar routes. Six-meter routes traversing the equator should experience consistent openings ±9 months from solar max.

Ricky Egeland is a participating member in the group headed up by Scott McIntosh and Bob Leamon that published a paper 9 months ago outlining the existence of magnetic bands within the sun that govern the sunspot and Hale cycles. At the time of its publishing, the paper went on to predict the peak of Solar Cycle 25 could be as high as Solar Cycle 21. Today’s release is a revised prediction based upon data observed since the original paper was published. To be sure we are still in early days. The solar rotation cycle, as marked by sunspot activity, was established on April 19, 2021, so we are only 90 days into actually observing Solar Cycle 25 activity. It is now agreed that the dramatic run-up in sunspot activity we experienced late last fall, while tied to Solar Cycle 25, was an outlier.

When asked directly about whether they can declare if the terminator event they wrote about in the fall 2020 paper has occurred, Scott McIntosh stated, “We can’t be sure just yet but we are very, very close.”

It also should be noted that while it has been over a year since the sun produced a Solar Cycle 24 region with a sunspot worthy of a NASA classification, the sun has been steadily producing spotless Solar Cycle 24 active regions, the last of which formed right on the solar equator at N00/W54 on July 24, 2021, as recorded by Jan Alvestad’s Solar Terrestrial Activity Report website. These active regions, being part of a Solar Cycle in its final stages of existence, produce no spots and only last for a few hours before they dissipate. The previous Solar Cycle 24 active region formed on June 28, 2021. Once the Solar Cycle 24 active regions cease altogether, Solar Cycle 25 will take off in earnest. — with thanks to Bob Marston, AA6XE

K7TLM reminds us that the United States Postal Service currently offers first-class stamps with wonderful solar images in a Sun Science series.

Sunspot numbers for July 29 – August 4 were 0, 0, 0, 0, 13, 15, and 14, with a mean of 6. The 10.7-centimeter flux was 75.8, 75.5, 75.9, 74.9, 74.6, 75.9, and 70.8, with a mean of 74.8. Estimated planetary A indices were 8, 6, 6, 4, 17, 10, and 5, with a mean of 8. Middle latitude A index was 12, 6, 6, 4, 13, 15, and 5, 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 this propagation page.

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.

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