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The K7RA Solar Update


We saw an increase in solar activity over the past week, and it appears that perhaps the second peak of Solar Cycle 24 is not over.

Average daily sunspot numbers from February 20-26 increased nearly 24 percent from the previous seven days, from 140.4 to 173.6.  Average daily solar flux over the same period rose from 158.7 to 167.3. On Thursday, February 27, the sunspot number increased from 197 on Wednesday to 227, which is over 30 percent above the average for the previous seven days.

Predicted solar flux over the near term is 175 on February 28, 175 on March 1-2, 165 on March 3-5, 170 on March 6, 175 on March 7, 180 on March 8-9, then 175 and 160 on March 10-11, 145 on March 12-13, 150 on March 14-17, and 155 on March 18-20, peaking at 180 on March 26 and again on April 2-4.

Predicted planetary A index is 25 and 8 on February 28 and March 1, 5 on March 2-6, 8 on March 7, 5 on March 8, 10 and 5 on March 9-10, 8 on March 11, and 5 on March 12-22. An echo of recent flare activity shows about 28 days later as a planetary A index of 15 on March 27-28.

OK1HH predicts the geomagnetic field will be quiet on February 28 through March 4, mostly quiet March 5, active to disturbed March 6, quiet to active March 7, active to disturbed March 8, quiet to unsettled March 9, mostly quiet March 10, quiet March 11-14, quiet to active March 15-16, mostly quiet March 17-18, and active to disturbed on March 19.

On Thursday, February 27 a CME hit Earth at 1645 UTC. This was from the X4.9 solar flare reported February 25. The planetary A index increased to 24, which was the same reading for Alaska’s college A index.  Mid-latitude A index was 15.

If you look at the Daily Sun image on the left side of the page at you will see it is peppered with sunspots. Unfortunately, sunspots in this cycle have not been very energetic, so we haven’t seen much of the higher MUF figures normally associated with this many spots.

There is a new aurora prediction tool online at .  OVATION was developed at the Johns Hopkins University Applied Physics Lab, and passed on to us by Robert Steenburgh, KA8JBY, who works at NOAA.

No e-mail from readers this week, for the first time in ages, so nothing to report from the field.

Tonight begins the phone weekend for the ARRL International DX Contest. It runs from March 1-2, 2014, which is actually 4:00 PM Friday through 3:59 PM Sunday here on the West Coast. See for details.

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve overseas locations are at

Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for February 20 through 26 were 140, 152, 179, 185, 205, 157, and 197, with a mean of 173.6. 10.7 cm flux was 156.4, 156.8, 163.2, 171.8, 170.7, 173.9, and 178.2, with a mean of 167.3. Estimated planetary A indices were 39, 12, 14, 17, 7, 4, and 4, with a mean of 13.9. Estimated mid-latitude A indices were 27, 9, 11, 12, 5, 3, and 3, with a mean of 10.




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