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The K7RA Solar Update

03/26/2021

Tad Cook, K7RA, Seattle, reports: On March 21 and 22 two new sunspot groups, 2811 and 2812, appeared. Average daily sunspot number this week faded a bit from 19 to 17.9, but average daily solar flux went from 78.1 to 78.6. Neither change is significant.

We haven’t seen a day with no sunspots since March 1, so that brings the percentage of spotless days so far this year to 38%, down from 57% last year and 77% in 2019.

Geomagnetic activity was steady throughout this week, with average daily planetary A index rising from 10.3 to 13.3, and average middle latitude A index from 7.3 to 10.4. But geomagnetic conditions were disturbed at higher latitudes.

Alaska’s College A index, measured near Fairbanks, was 40 and 45 on March 20 – 21. This was reflected in a report from N6QEK/KL7 in North Pole, Alaska (a town southeast of Fairbanks, not at the North Pole), who wrote, “HF frequencies here in the interior of Alaska were wiped out for the BARTG RTTY contest. FT8 signals were almost nonexistent as well.”

Saturday was the first day of spring in the Northern Hemisphere and fall in the Southern Hemisphere, positive indications for HF propagation.

Predicted solar flux over the next month is 80 on March 26 – 27; 75 on March 28 – 31; 70 on April 1 – 2; 80 and 81 on April 3 – 4; 82 on April 5 – 7; 81 on April 8; 80 on April 9 – 10; 78 and 76 on April 11 – 12; 75 on April 13 – 14; 76 on April 15; 77 on April 16 – 17; 76 on April 18 – 20, 77 on April 21, and 78 on April 22 – 28. Solar flux is expected to peak at 82 on May 2 – 4.

Predicted planetary A index is 8 on March 26; 5 on March 27; 25 on March 28; 20 on March 29 – 30; 12 on March 31; 8 on April 1 – 3; 5 on April 4 – 7; 15, 18, and 20 on April 8 – 10; 5 on April 11 – 15; 25, 22, 20, 15, and 8 on April 16 – 20; 5 on April 21 – 23; 25 on April 24, and 20 on April 25 – 26.

Here’s the geomagnetic activity forecast for March 26 – April 20 from F.K. Janda, OK1HH.

The geomagnetic field will be:

  • quiet on April 1, 6 – 7, 12 – 13

  • quiet to unsettled on March 26 – 27, 31, April 5, 14, 18

  • quiet to active on April 2 – 4, 15, 20

  • unsettled to active March 29, April 8, 11, 19

  • active to disturbed March 28, 30, April 9 – 10, 16 – 17

  • Solar wind will intensify on March (28,) 29 – 30, (31,) April 2 – 3, (4 – 6, 8 – 9,) 10 – 11, (12, 16 – 17,) 18 – 19, (20)

Remarks:

Parenthesis means lower probability of activity enhancement.

Predictability of changes remains very low, as there are irregular and ambiguous indications.

Jon Jones, N0JK, wrote on March 22:

“More on the March 13 sporadic-E opening. The month of March has the lowest occurrence of sporadic-E propagation of any month of the year. Thus, I consider any sporadic-E on 6 meters in March noteworthy.

“There was some afternoon TEP (transequatorial propagation) on 6 meters between Florida and South America March 21. Stations such as W4AS, KD4ESV, KV4HV, in Florida worked CX and LU stations around 2100 UTC. K0GU (DN70) in Colorado spotted LU9FVS, perhaps a sporadic-E to TEP link. The K index was 5, indicating ‘storm’ geomagnetic field conditions.”

This article mentions solar cycle predictions and mentions predicted “peak rates of more than 200 sunspots at a time.” But the writer may have made a common error, confusing the daily sunspot number with the actual number of sunspots — two very different numbers.

To review, to calculate the sunspot number, we count a value of 10 for each sunspot group, than add a value of 1 for each sunspot within those groups.

I noticed something strange about the NOAA SESC reported solar flux of 79 on March 23. NOAA gets the solar flux values from the Penticton, British Columbia, Dominion Radio Astrophysical Observatory noon reading, which is also my source. NOAA rounds off these values to the nearest whole number, which should have been 82.

Now that it is March, I will pause to reflect. The FCC issued my Novice license (WN7CSK) on March 23, 1965, when I was 12 years old. When the ticket finally arrived, I was very, very excited.

I asked my mother to hang her bright red sweater in the dining room window when any envelope from the FCC arrived, so I could see it from my school bus. When I saw Mom’s sweater, I leaped from my seat, and ran to the front of the bus, whooping and hollering. This only confirmed for my schoolmates what they already knew, that I really was crazy. Fifty-six years later, this vivid memory lingers.

It was 30 years ago (this week?) that I began writing this bulletin after a sudden increase in solar flux that I felt was noteworthy. But, ARRL had just announced that Ed Tilton, W1HDQ, who authored this propagation bulletin was ill, so it was suspended for the time being.

I fell into writing the bulletin when I called ARRL Headquarters, because I thought it should put out a bulletin with this solar news. The individual I spoke with wondered who might write this, so I offered. Then, the next week Headquarters asked for another bulletin.

I also called W1HDQ, who at that time was living in Florida. His wife answered the phone, but said he was too ill to talk on the phone. She asked what I was calling about, and when I told her the solar flux value, she replied, “Oh he’ll want to hear about this!” and I spoke with Ed briefly, who seemed exited by the news.

Unfortunately, W1HDQ never recovered, so I kept writing the ARRL Propagation Bulletin. I have since been unable to learn when he began writing it. I recall copying the bulletin from W1AW on 20-meter CW in 1966, but before that is unclear. Nobody seems to know. I wish I had asked Ed about this when we spoke.

Sunspot numbers for March 18 – 24 were 12, 14, 12, 12, 23, 26, and 26, with a mean of 17.9. The 10.7-centimeter flux was 73.4, 73.5, 80.3, 77.1, 80.4, 81.8, and 83.6, with a mean of 78.6. Estimated planetary A indices were 4, 6, 29, 24, 8, 11, and 11, with a mean of 13.3. Middle latitude A index was 4, 6, 20, 17, 6, 9, and 11, with a mean of 10.4.

For more information concerning radio propagation, visit the ARRL Technical Information Service, read “What the Numbers Mean…,” and check out K9LA’s 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.

Share your reports and observations.

 



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