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The K7RA Solar Update


Tad Cook, K7RA, Seattle, reports: Three new sunspot groups appeared on February 3, 6, and 8. Average daily sunspot number rose slightly during the February 3 – 9 reporting week, from 81.3 last week to 83.9. Average daily solar flux also increased modestly, from 123.1 to 126.

Solar flares and geomagnetic storms this week raised the average daily planetary A index from 10.1 to 14.4, and the middle latitude A index — measured at one location in Virginia — went from 6.4 to 9.6.

At 0523 UTC on February 11, the Australian Space Forecast Centre issued a Geomagnetic Disturbance Warning. “A recurrent coronal hole is expected to cause unsettled to active conditions with possible minor storm periods on 12 to 13 February.”

A geomagnetic storm on February 4 brought down 40 of 49 just-launched low-Earth orbit Starlink satellites, even though the storm was not especially robust. But February 3-4, the high latitude college A index measured near Fairbanks, Alaska, was 48 and 61, a level that assures the appearance of aurora borealis.

NN4X shared this Business Insider article on the loss of the Starlink satellites.

We typically think of geo-storms as a negative event in terms of HF radio propagation, but not always. Sometimes, signals propagate by bouncing off the aurora.

In this vein, K7SS commented at 2030 UTC on February 10 in an email posting titled, “EU aurora on 10 meter CW.” He said:

“Weak OH, SM, UA, opening now. All aurora-sounding. Point ’em north.”

“All aurora-sounding” refers to the unusual garbled fluttery sounds of auroral propagation, best taken advantage of by pointing antennas north to propagate signals via the aurora.

W7YED responded:

“I saw two SM3s at around 2100 UTC calling CQ on 10-meter FT8. One worked an XE, lasted about 5 mins then went away. And now back to the regularly scheduled Caribbean and SA stations. Things are looking up on 10.”

So far this year, sunspots were visible on every day. Last year, 64 days had no sunspots, and in 2020, 208 days were spotless, according to

Predicted solar flux values for the near term are 118 and 116 on February 11 – 12; 112 on February 13 – 14; 110 on February 15 – 16; 112 on February 17; 115 on February 18 – 19; 118 on February 20; 120 on February 21 – 23; 125 on February 24 – 25; 120 on February 26 – March 4; 115 and 122 on March 5 – 6; 120 on March 7 – 9; 110 on March 10 – 11; 115 on March 12 – 18; 118 on March 19, and 120 on March 20 – 22.

Predicted planetary A index is 20, 12, 22, and 25 on February 11 – 14; 20, 12, 8, 10, and 8 on February 15 – 19; 5, 10, 8, 5, 8, and 12 on February 20 – 25; 8 on February 26 – 27; 5 on February 28 – March 2; 12, 10, 15, and 10 on March 3 – 6; 5 on March 7 – 11; 25 and 20 on March 12 – 13; 5 on March 14 – 15, and 10, 12, and 8 on March 16 – 18.

F.K. Janda, OK1HH, offered this commentary:

“I would like to return once again to the solar flare M1 in AR2936 on January 29, accompanied by LDE, which caused the halo CME. The CME was met near Earth by 49 Starlink satellites launched on February 3 into low-Earth orbit from Kennedy Space Center in Florida. As a result, 40 of them did not reached planned orbit and then burned up in the atmosphere in a controlled manner. The cost to launch the Falcon 9 is $30 million, one satellite is $500,000, total damage to Elon Musk = $50 million.

“Solar activity in Solar Cycle 25 is rising faster than most models anticipated. More accurate predictions of further developments are complicated by the fact that there are several irregularly evolving active areas on the Sun at the same time. For this reason too, we cannot rely on the 27-day periodicity, which is otherwise a good tool for compiling forecasts. If we take advantage of it, we can expect the next major disturbance on 13 – 14 February. Things can be expected to calm after February 16, with quiet days after February 19. Solar flux should not fall below 100 or rise too much above 130.”

Space Weather Woman Tamitha Skov, WX6SWW, has posted this update.

N8II reported from West Virginia on February 7:

“I was active in the Vermont, Minnesota, and British Columbia QSO parties this past weekend. Conditions were excellent to Minnesota on 20, with loud signals from 1500 UTC until about 2230 UTC (our sunset was 2237 UTC). Even the mobiles were very good copy, many quite loud on 20. Forty meters suffered from D/E layer absorption, with almost all Minnesota signals below my noise level 1700 – 2030 UTC. Eighty was open well before Minnesota sunset, with workable signals at 2300 UTC and some very good signals by 2330 UTC. 

“Fifteen and even ten meters were open to British Columbia both weekend days. The peak of 10-meter propagation was in the 1900 UTC hour both days, with Saturday being better on both 20 and 15. Several British Columbia signals on 10 meters were greater than S-9 on Saturday. Many US Rocky Mountain-area and west coast signals were on the band as well. Twenty-meter conditions were excellent Saturday, 1600 – 2400 UTC, but 15 and 10 were slow to open Sunday finally opening around 1830 UTC.

“Propagation to Vermont was about as expected, some loud signals 0000 – 0030 UTC on 40 and mostly loud stations on 75/80. Signals on 160 were fairly weak Friday PM. There was no miracle Es opening like last year, 20 meters was open on backscatter only, and W1JXN was worked on 15-meter CW backscatter just above the noise.

“Sunday morning, February 6 saw a good 10-meter opening to southern Europe. I had an SSB run 1515 – 1550 UTC, working Croatia, Switzerland, Spain, and many French and Italian stations. Many signals were over S-9. Twelve meters in the past few days has been open each day, at least to southern Europe.

“Last Friday, February 4, 10 meters was wide open to New Caledonia, 2130 – 2245 UTC. I easily logged FK8IK on both CW and SSB, and FK4QX on SSB. This followed loud signals from the western US.”

Here are some images of recent sunspot regions.

This study offers an explanation for unusual motions in solar flares, oddly referred to as “solar flames.”

Sunspot numbers for February 3 – 9 were 84, 87, 91, 83, 78, 86, and 78, with a mean of 83.9. The 10.7-centimeter flux was 126.5, 129.6, 125.9, 123.6, 127.2, 123.1, and 125.9, with a mean of 126. Estimated planetary A indices were 27, 32, 12, 15, 7, 5, and 3, with a mean of 14.4. Middle latitude A index was 18, 18, 10, 12, 4, 3, and 2, with a mean of 9.6.

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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