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The K7RA Solar Update (01/10/2023)



Two new sunspot groups emerged on December 29, one more on December 30 and another on January 1, then two more on January 5.


Solar activity was a little higher, with average daily sunspot number rising from 96.1 to 97, and solar flux averages rose 14 points to 157.8.


On Thursday, January 5 the sunspot number rose to 103, above the average of 96.1 over the previous seven days.


Predicted solar flux is 154 on January 6, 152 on January 7-8, 150 on January 9, 148 on January 10-11, then 146, 148 and 145 on January 12-14, 140 on January 15-16, 145 on January 17-19, 150 and 155 on January 20-21, 160 on January 22-23, 165 on January 24-26, then 160, 155, 155, 158 and 155 on January 27-31, 150 and 148 on February 1-2, 145 on February 3-4, 140 on February 5-6, 150 on February 7-9, 145 on February 10, 140 on February 11-12, and 145 on February 13-15.


Predicted planetary A index is 12 and 8 on January 6-7, 5 on January 8-16, then 8, 12, 25, 20 and 10 on January 17-21, 5 on January 22-24, then 8, 28, 15 and 10 on January 25-28, and 5 on January 29-30, 18 on January 31 through February 1,15 and 10 on February 2-3, and 5 on February 4-12.


OK1HH wrote:


"Solar activity increased so rapidly in recent years that earlier last year it already reached the level predicted for July 2025, the predicted peak of the current 25th solar cycle. The year 2022 ended with the highest monthly sunspot count in 7 years.


"Solar flares are already routinely of moderate magnitude (M-class in X-rays), while geomagnetic disturbances are so far only very rarely in a higher class than G1 (minor). In the G1 class was also the disturbance on 30 December, which was triggered by a CIR (co-rotating interaction region) impact, as predicted.


"This week the Earth is in the impact zone of possible eruptions in the AR3176 sunspot group directly opposite our planet, which produces M-class solar flares. The strongest so far, on December 30 at 1938 UTC, was class M3.7, which sent a CME toward Earth with an expected arrival on January 4 - and the prediction proved correct - the disturbance began at 0254 UTC.


"The CMEs filled the space between the Sun and Earth, and clouds of solar plasma shielded the incoming cosmic rays enough to reach a six-year low.


"Thus, since 26 December, we can observe the 'Forbush Decline,' named after the American physicist Scott Forbush, who studied cosmic rays in the early 20th century and first noticed the relationship between them and solar activity. With more CMEs hitting Earth, the cosmic ray decline will grow.


"On January 3 at 1058 UTC, something exploded on the far side of the Sun. The Solar and Heliospheric Observatory (SOHO) detected a bright CME sweeping across the southeastern limb of the Sun. The source of the outburst was likely the old sunspot AR3163, which has been on the Sun's far side for the past two weeks. We are now starting to see it on the solar disk as AR3182, and we might tentatively expect an X-class flare from it.


"The Geminid meteor shower is coming to Earth these days. On the first three days of January, the most meteors arrived on January 3 at 2127 UTC when the Zenithal Hourly Rate (ZHR) of 125.3 was calculated. Also, the activity of the sporadic-E layer in the ionosphere increased, which we immediately noticed in the fading shortwave propagation conditions (because sporadic-E is sporadic).


"ZHR (Zenithal Hourly Rate) of a meteor shower is the number of meteors a single observer would see in an hour of peak activity if it was at the zenith, assuming the observing conditions are excellent (when and where stars with apparent magnitudes up to 6.5 are visible to the naked eye)."


OK1HH mentioned sunspot numbers are ahead of the consensus forecast for Solar Cycle 25, so we will compare averages from a year ago with current numbers.


In Propagation Forecast Bulletin ARLP001 for 2022, the average sunspot number reported was 36.4, and 97 in the current report. Average solar flux a year ago was 91.4, compared to 157.8 this week.


Reader David Moore sends along this link about our Sun's corona:



Here is an article on Siberian Radioheliograph:



Solar outburst:



A record of old sunspot numbers can be found here:



Solar Terrestrial Activity Report:



Identifying unknown HF signals:



Send your tips, reports, observations, questions, and comments to


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 December 29, 2022 through January 4, 2023 were 113, 121, 82, 94, 94, 89, and 86, with a mean of 97. 10.7 cm flux was 162.8, 178.3, 164.9, 152.6, 146.4, 148.5, and 151, with a mean of 157.8. Estimated planetary A indices were 11, 31, 16, 14, 8, 7, and 21, with a mean of 15.4. Middle latitude A index was 8, 22, 10, 9, 5, 5, and 17, with a mean of 10.9.



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