Sunspot numbers and solar flux declined over the past week relative to the previous seven days. Average daily sunspot number went from 86.6 to 56.7, while average daily solar flux slid from 117.4 to 107.8. Geomagnetic indices were up. Average daily planetary A index went from 9.4 to 17.7, and mid-latitude A index went from 7.4 to 12.6.

Early in this week Spaceweather.com was anticipating a CME, but instead we got a stiff solar wind, causing the planetary A index to rise to 38 on February 16 and 34 on February 17. This will most likely subside.

Predicted planetary A index is 20, 12 and 8 on February 19-21, 5 on February 22-29, then 15, 10, 12 and 8 on March 1-4, then 5, 15, 10 and 8 on March 5-8, then 5 on March 9-10, then 8, 5, 27 and 12 on March 11-14, and 20, 12, 10 and 8 on March 15-18, and 5 on March 19-27.

Predicted solar flux is 95 on February 19-20, 100 on February 21-23, 105 on February 24-25, 110 on February 26, 115 on February 27-28, 118 on February 29, 120 on March 1-3, 115 on March 4-5, 110 on March 6-7, 105 on March 8-12, 108 on March 13-14, then 105, 103, 106, 107 and 110 on March 15-19, and 115 on March 20-26.

This week OK1MGW believes geomagnetic field activity (which the A index expresses as numeric values) quiet to unsettled February 19-20, mostly quiet February 21, quiet on February 22-25, mostly quiet February 26, quiet to unsettled February 27-28, quiet to active February 29 to March 1, quiet to unsettled March 2, quiet to active March 3, quiet to unsettled March 4, quiet to active again on March 5-6, quiet to unsettled March 7-8, quiet to active March 9-10, quiet to unsettled March 11-12, quiet to active March 13, active to disturbed March 14-15, and quiet to active March 16.

Jeff, N8II, in Shepherdstown, West Virginia (FM19cj) wrote on February 12, “Today SFI (solar flux) down 1, K index 3 at 1500Z.  Ten meters was very slow to open to Europe today, but finally around 1520Z, I started working fairly loud Germans/Netherlands/Belgium/Italy/Switzerland, some very loud signals and a few weak ones. I worked one summit activator in DL who was over S9, but think he was using a Yagi and was not QRP. Still open well at 1630Z when I went QRT. 12 meters was open much earlier, but a bit spotty in coverage.”

A fascinating article appeared in Sky and Telescope on Valentine’s Day, about how sunspots are counted: http://bit.ly/1KkpeDK or http://goo.gl/I0kyvt

The third paragraph mentions “all sorts of models” which use sunspot records to predict “climate, orbit of satellites, and stability of power grids.” I would caution though that back in the 1970s and earlier, climate scientists tried to correlate solar activity with climate, and found a weak correlation, which only worked prior to the industrial age.

Regarding the stability of power grids, this probably refers to blasts of CME energy and solar wind, which you may have noticed seem to peak after solar maximum. We are seeing this right now, and I have noticed it in previous sunspot cycles.


NN4X sent this, concerning the solar dynamic observatory: http://www.space.com/31942-suns-busy-buzzy-life-1-year-in-2-5-minutes-4k-video.html

Here is an article claiming another solar max in 2023, nine years after the recent solar maximum. But why do they use my first name at the start of paragraph two? Is TAD an acronym? Or maybe this is from another subculture I am not familiar with, where the expression “Tad Dramatic” is widely understood? I wish I knew, but I must admit, rather like that expression.

This paragraph is interesting: “This solar cycle decline helps to disprove solar hypotheses stating that the witnessed temperature rise on Earth would be caused to extra solar activity, if solar played any significant role over the last couple of decades, it should have manifested a net cooling trend.”

But we don’t cover climate in this bulletin.

Dr Jon K. Jones, MD, N0JK, of Lawrence, Kansas wrote on February 18, concerning six meters: “A geomagnetic storm is in progress February 16-19 with the 24 hour K index on February 18 peaking at 6.
“Some aurora was worked on 6 meters from Minnesota February 17:

“K0SIX, 2329Z 50125 EN34 Au EN35 by WB4SIA
K0SIX, 2329Z 50125 EN35 EN44 by K9MU

“The following morning, February 18, strong sporadic E on 6 meters from Florida to Illinois, Indiana, Michigan and Ohio. The 1 watt WA3TTS/b was copied 559 on 6 meters by K8XX in EL88 Florida.
Some spots, all from February 18:

“WA3TTS/B, 1416Z  50068 el90  1 W ERP heard 55 in el88 by K8XX
K9OIM, 1402Z  50125 el98 by KC8UDV
KJ4E, 1358Z 50125 59 +20 by KC8UDV
K8MMM/B, 1355Z 50010EL98IT<>EN91IG 59+, by KJ4E
W3PIE/B, 1339Z 50062 EL98IT<>FM09MM by KJ4E
WA8FTA, 1335Z 50098 EL98IT<>EN52MK by KJ4E
KJ4E,1326Z 50099 EN62AX<AUE>EL9 by WA9CAT
WA9CAT, 1325Z 50099 EL98IT EN62AX TU QSO by KJ4E”

The DX maps show some of the paths toward the end of the opening. The Es may have been associated with the geomagnetic activity.


This weekend is the big ARRL International DX Contest (CW). According to the rules, the objective is "To encourage W/VE stations to expand knowledge of DX propagation on the HF and MF bands, improve operating skills, and improve station capability by creating a competition in which DX stations may only contact W/VE stations." It begins this evening (Friday, North America time) at 0000 UTC Saturday and ends 2359 UTC Sunday. See here for more details and rules: http://www.arrl.org/arrl-dx


For more information concerning radio propagation, see the ARRL Technical Information Service at http://arrl.org/propagation-of-rf-signals. For an explanation of the 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/.

My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .

Click on “Download this file” to download the archive, and ignore the security warning about file format. Pop-up blockers may suppress the download.

Monthly propagation charts between four USA regions and twelve overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL bulletins are at http://arrl.org/bulletins.

Sunspot numbers for February 11 through 17 were 68, 74, 46, 52, 48, 49, and 60, with a mean of 56.7. 10.7 cm flux was 112.8, 112.2, 110.3, 108, 107.3, 104, and 99.9, with a mean of 107.8. Estimated planetary A indices were 11, 13, 7, 10, 11, 38, and 34, with a mean of 17.7. Estimated mid-latitude A indices were 8, 11, 7, 6, 10, 25, and 21, with a mean of 12.6.