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The K7RA Solar Update

02/26/2021

Tad Cook, K7RA, Seattle, reports: Sunspots have returned, and solar activity increased on every day over the reporting week. On Thursday evening, Spaceweather.com reported that sunspot group AR2804 had doubled in size in a single day.

The total sunspot area was 200 millionths of a solar hemisphere, a level not seen since the end of last year. It actually took 2 days to double — Tuesday through Thursday — covering 100, 150, and then 200.

The average daily sunspot number increased from zero to 19.6, while average daily solar flux rose from 72 to 75.7. Geomagnetic activity was also higher, with average daily planetary A index increasing from 7.7 to 16, and average daily mid-latitude A index rose from 5.6 to 12.4.

Predicted solar flux for the next 30 days is 80 on February 26 – 28, 78 on March 1; 74 on March 2 – 5; 73 on March 5 – 6; 74, 70, 74, and 76 on March 7 – 10; 72, 71, 72, and 70 on March 11 – 14; 71, 72, 71, 73, 76, and 75 on March 15 – 20; 72 on March 21 – 22; 76 on March 23 – 24; 74 and 73 on March 25 – 26, and 74 and 73 again on March 27 – 28.

Predicted planetary A index is 5 on February 26 – March 1; 18 and 12 on March 2 – 3; 10, 8, and 15 on March 4 – 6; 5 on March 7 – 11; 15, 10, and 5 on March 12 – 14; 15, 5, 8, and 18 on March 15 – 18; 20 on March 19 – 20; 10 and 8 on March 21 – 22, and 5 on March 23 – 27.

The University of Bradford in the UK has an article, “Automated Solar Activicty Prediction (ASAP)” on its website. While this looks interesting, so far I have been unable to download any data more recent than 2009 or 2011.

Here’s the geomagnetic activity forecast for February 26 – March 23 from F.K. Janda, OK1HH, and the Czech Propagation Interest Group, which has been compiling these weekly forecasts since January 1978.

The geomagnetic field will be:

  • quiet on March 9 – 10, 14

  • quiet to unsettled on February 26 – 27, March 4 – 5, 13, 16 – 17, 20

  • quiet to active on (February 28,) March 2 – 3, 7 – 8, 11, 15, 18 – 19, 21 – 23

  • unsettled to active March (1,) 6, 12

  • active to disturbed nothing expected

  • Solar wind will intensify on February 28, March 1 – 3, (4 – 9, 12,) 13, (14, 16 – 22,)

Parentheses mean lower probability of activity enhancement. Predictability of changes remains low, as some indications are ambiguous.

The Space Weather Woman Tamitha Skov, WX6SWW, has posted this new video.

An article in Forbes magazine describes recent space weather as “spicy:”

An article on the Weatherboy site predicted “potent solar wind” for Monday, February 22, and included some interesting graphics:

An article in the UK tabloid Express describes a solar “canyon of fire,” but you need to page through a lot of other stuff to read the whole article.

Ken Brown, N4SO (EM50tk), wrote on February 19:

“One measure of propagation is to call CQ at a very low power on CW and look for returns on the Reverse Beacon Network. This was done with the [Elecraft] K2 power control knob all the way down, and on an Elecraft W1 power meter reading 100 mw on the lowest scale. Several CQs were called. KD7YZ responded with a single spot. Location: Greenup, Kentucky (EM88ll).” This was on 30 meters on February 14.

This weekend is the CQ 160-Meter SSB Contest.

Sunspot numbers for February 18 – 24 were 12, 12, 12, 11, 26, 31, and 33, with a mean of 19.6. The 10.7-centimeter flux was 71.1, 72.9, 76.4, 75.3, 75.9, 78.1, and 80.5, with a mean of 75.7. Estimated planetary A indices were 5, 17, 20, 20, 17, 12, and 21, with a mean of 16. Middle latitude A index was 2, 13, 15, 18, 13, 10, and 16, with a mean of 12.4.

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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