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The K7RA Solar Update


Tad Cook, K7RA, Seattle, reports: Solar activity was up this week. Average daily sunspot number increased from 26.9 to 46.1, and average daily solar flux was up 10.8 points to 90.9. Geomagnetic indicators were a little higher. Average daily planetary A index increased from 7.9 to 8.7, and average daily middle latitude A index from 5.4 to 6.3.

I like looking for openings on 10 meters and continue to be surprised by how often I hear nothing (when probing with FT8 and pskreporter) but find plentiful openings on 12 meters, indicating the MUF is somewhere between 10 and 12 meters. To help 10-meter observers, I have a CW propagation beacon on 28.2833 MHz, K7RA/b in Seattle. It runs about 10 W into a half-wave dipole at a modest height. 

Two new sunspot groups emerged on November 26, one on November 28, and two more on November 30.

On December 1, announced a geomagnetic storm watch: “Minor geomagnetic storms are possible on December 3 when a CME might sideswipe Earth’s magnetic field. The storm cloud was hurled into space on Nov. 29th by an erupting filament of magnetism in the sun’s southern hemisphere. According to NOAA computer models, the bulk of the CME should sail south of our planet with a near miss just as likely as a glancing blow.”

At 2340 UTC on December 2, the Australian Space Forecast Centre issued a Geomagnetic Disturbance Warning: “The effects of a coronal hole windstream and coronal mass ejection are expected to increase geomagnetic activity on 03 December.

Conditions are likely to be initially quiet with activity increasing. Active to minor storm levels are expected.”

Predicted solar flux for the next month has flux values peaking at 94 on December 27 – 28. The forecast sees values of 86 on December 3; 84 on December 4 – 5; 82 on December 6; 80 on December 7 – 10; 82 on December 11 – 12; 80 on December 13 – 14; 85 on December 15 – 21; 82 and 80 on December 22 – 23; 78 on December 24 – 25; 92 on December 26; 94 on December 27 – 28; 88 on December 29 – January 1, then 85, 82, and 80 on January 2 – 4; 82 on January 5 – 8, and 80 on January 9 – 10.

Predicted planetary A index is 12, 14, 10, and 12 on December 3 – 6; 8 on December 7 – 8; 5 on December 9 – 11; 8, 12 and, 10 on December 12 – 14; 5 on December 15 – 16; then 8 and 10 on December 17 – 18; 5 on December 19 – 25; 8 on December 26; 5 on December 27 – 29; 10 on December 30 – 31; 8 on January 1; 5 on January 2 – 7, and 8, 12, and, 10 on January 8 – 10.

AA6XE wrote:

“We now stand at exactly 2 years since the Cycle 24/25 minimum was recorded, and the most notable attribute of Cycle 25 is its slow climb out. We have seen bursts of activity from the sun where numerous active regions pop up with only a handful actually developing into numbered sunspot groups. The bulk of the new regions that form quickly decay away. As it stands right now Solar Cycle 25 activity is running a little bit ahead of the same point in Solar Cycle 24. Does this point to a weak Solar Cycle much like we experienced with Solar Cycle 24? It’s still too early to say. The first couple of years in any Solar Cycle are never easy to take and Cycle 25 is proving itself no exception. We await ‘the breakout,’ when solar activity ramps up dramatically.

“A dramatic run-up in solar flux over a period of a few days has little influence on increasing ionospheric MUF. What does have an effect on the ionospheric MUF is an increase in the monthly solar flux average and, more significantly, an increase of the 90-day mean solar flux reading. The dramatic and unanticipated spike in sunspot activity we saw a year ago, November 2020, temporarily boosted the 90-day solar flux average, which had been running in the low 70s at the time, into the low 80s in the ensuing 60 days. It became quickly apparent the November 2020 event was an outlier, and the 90-day solar flux subsequently slipped back to the mid-70s by mid-April 2021. Since that time the 90-day solar flux average has been rising steadily, albeit slowly. As long as those figures continue to steadily chug uphill, the MUF will continue to rise. The 90-ay solar flux average as it stands presently is in the upper 80s. The 90-day solar flux mean will be in the low 90s by the end of December if Solar Activity resumes the pace of growth we saw early in the fall. The solar breakout predicted by folks at the National Center for Atmospheric Research (NCAR) has not materialized in time to provide any sort of relief to the winter doldrums we typically experience.

“On the bright side, this winter is shaping up to be one of the best we will see for 160-meter DX in the last several years. Solar activity has picked up just enough to increase ionization at those frequencies with little or no increase in D-Layer absorption, while the Planetary K Index has remained low.”

On November 29, N0JK, reported from Kansas:

“There was 6-meter sporadic-E on Thanksgiving. From Kansas I worked WB5TUF (EL29) and NE5U (rare grid EL19) around 0240 UTC November 25 on 50. 313 MHz FT8. N0LL (EM09) worked NR4J (EM60) at 1625 UTC on FT8 on November 25.”

From OK1HH:

“Weekly commentary on phenomena in the sun, in the magnetosphere, and in the ionosphere of the Earth: One week ago, I compiled my last weekly forecast of Earth’s magnetic field activity. Primarily, my goal was to compile predictions of changes in the ionospheric propagation of decameter waves. Their first users were my friends — radio amateurs. But 45 years ago no one provided available predictions. That’s why I gradually learned to compile them myself. Today, actually applicable predictions are available from several sources on a weekly and daily basis, especially in the US, Belgium, Australia, Russia, and, to my delight, also in the Czech Republic. In the meantime, I had long since reached retirement age and planned to finally quit. But I was asked to try to continue, using my experience. Therefore, from now I will try to write comments on current and upcoming development. If this activity will be found as useful and/or interesting, I will continue. And like 45 years ago, it’s an experiment. So here is my first attempt:

Solar activity remains at current levels, and due to the location of solar coronal holes near the central meridian, the influx of faster solar winds can be expected to continue. The irregular daily course of changes in the ionosphere, to which the relatively low or still declining solar activity will contribute, should continue in the next 5 days or so.

In addition, after the CME on November 29, it is still possible for the plasma cloud to arrive late on December 2 or on December 3, but the probability is already low.

After the expected slight increase in solar activity, I expect a more regular course of ionosphere parameters in the second half of December.”  F. K. Janda, OK1HH

Email: ok1hh(at), ok1hh(at); Pmail: OK1HH(at)OK0NAG.#BOH.CZE.EU.

NASA’s new solar tour feature starts today:

Sunspot rotation rate history.

Sunspot variations during their decay.

Dynamics of bright features.

Space Weather Woman Tamitha Skov, WX6SWW, posted her latest space weather analysis on December 1.

Sunspot numbers for November 25 – December 1 were 20, 52, 53, 53, 47, 61, and 37, with a mean of 46.1. 10.7 cm flux was 93.6, 92.3, 91.8, 92.2, 89.8, 90, and 86.4, with a mean of 90.9. Estimated planetary A indices were 5, 4, 5, 9, 9, 11, and 18, with a mean of 8.7. Middle latitude A index was 3, 3, 3, 7, 6, 8, and 14, with a mean of 6.3.

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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