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The K7RA Solar Update


I thought it was too early in the decline of this solar cycle to start seeing days with no sunspots (when the sunspot number is zero), but I was wrong.

There were no sunspots on June 3-6. 2015 had zero spotless days, 2014 had just one, and there were no spotless days in 2012-2013. There were just two spotless days in 2011, so we have already seen twice the number of spotless days that 2011 had. 2010 had 51 spotless days, and 2009 had 260 spotless days.

The last time there were four or more spotless days was December 18-24, 2010 when there were no sunspots for an entire week.

The average daily sunspot number dropped to 7.7 this week, from 33 the week before. Average daily solar flux went from 87.4 to 80.7.  Geomagnetic indicators were up slightly, with planetary A index going from 8.9 to 11.6 and mid-latitude A index from 9 to 9.4.

As of Thursday, June 9, sunspots and solar flux both seemed to be recovering.

Daily sunspot number on June 7-9 was 12, 15 and 22, and daily solar flux was 78.5, 80.1 and 85.2.

Predicted solar flux for the near term is 85, 90 and 95 on June 10-12, 90 on June 13-14, 95 on June 15-16, 90 on June 17-20, 85 on June 21-24, 80 on June 25-28, 78 on June 29 through July 4, 82 on July 5-7, 85 on July 8-11, 90 on July 12-17 and 85 on July 18-21.

Predicted planetary A index is 8, 14, and 18 on June 10-12, then 12, 8 and 6 on June 13-15, 10 on June 16-18, 5 on June 19-22, then 10, 12 and 8 on June 23-25, 10 on June 26-27, 5 on June 28 through July 1, then 25, 20 and 8 on July 2-4, 5 on July 5-8, 12 on July 9-10, then 8 on July 11-12, then 5, 15 and 10 on July 13-15, and 5 on July 16-19.

Petr Kolman, OK1MGW, of the Czech Propagation Interest Group sends his geomagnetic forecast:

Geomagnetic field will be:
Quiet on June 19-20, July 1
Mostly quiet on June 15-16, 21-22, 29-30, July 5-6
Quiet to unsettled on June 10, 14, 25, 28, July 4
Quiet to active on June 11-13, 17-18, 23-24, 26-27
Active to disturbed on June (18), July 2-3

Increases of the solar wind from coronal holes are expected on June 11-13, 17-18, 23-24, 26-27, July 2-3

- Parenthesis means lower probability of activity enhancement.

Average daily solar flux over this past week was 80.7, but back in December 2010 that week of no sunspot numbers had an average daily solar flux of 79.3, very close.

Sunspot numbers are somewhat subjective, based on a visual count of sunspot groups, the number of sunspots in those groups, and the total area covered by sunspots.

Solar flux is an actual measure of one type of radiation reaching us from the sun, radio energy with a wavelength of 10.7 cm, or 2.8 GHz. This is supposed to give us a clue about how much our ionosphere is being charged, although x-rays have greater significance. Also remember that because the distance from earth to the sun varies slightly throughout the year, this affects the solar flux number because it is weaker when we are farther away.

We are only two weeks away from Field Day weekend, so what conditions might we see on June 25-26? The predicted solar flux for June 24-26 is 85, 80 and 80, while the predicted planetary A index is 12, 8 and 10, which is not bad.

We are including Friday in the data report, even though Field Day only runs from 1800 UTC Saturday, June 25 until 2059 UTC Sunday, June 26 because Friday conditions should affect conditions on Saturday.

We received this from N8II on June 9, which he titled “Late WPX Report”: “Recently the solar flux has dropped substantially to 80 as of today and I heard no signals on 15 meters an hour before sunset here. It was over 100 as I recall during the WPX CW contest May 28-29 and the band really came to life for the contest.

“Fifteen meters sounded so good Friday night, I decided to try single band. I never have heard so many New Zealand prefixes as I worked Friday evening, ZL1, 4, ZM1, 2, 3, 4 and there were multiple ZL1s and 4s active. To boot I worked 5W1 (western Samoa), WH6, NH7, KH6 x 3, VK2, 3, 4, 6 (though on 15 meters), VK7, JA2, 3, JH4 (Japan, all weak). The biggest surprise was a loud EA3 in Spain with my Yagi pointed west (off back).

“California stations were noticeably weak most of the evening as were some 7s. I closed out the evening with an A31 at 0230Z with 135 QSOs in the log. At 1747Z I found almost no EU (did get A60, United Arab Emirates) and not many USA stations either, so I bagged it in after 8 minutes. A check of the band at 2025Z revealed not only southern EU, but loud northern EU, UR, and UA6 area stations. About the only areas missing were North Russia, France, Netherlands, and British Isles.

“I logged several Lithuanians, Swedes, and Finns (Aland Island was very loud). The activity died off by 2120Z, but I was still working a mixture of EU and Caribbean/SA up until 2154Z when I worked a loud Sicilian and the shut down for dinner.

“Conditions from 2330Z were similar to the day before with a weak JA opening from 0151-0211Z when I decided to quit. Of note was an S7 Finn at 2340Z, which was 0234 local time in Finland! Again, California was weak most of the evening, but there were some nice prefixes to the south like XR0Y (Easter Island) and T49.

“Sunday morning I missed a good opportunity, because the band opened well much earlier to EU than it ever has for weeks. Signals were loud from all of EU at my 1253Z start and even a RU9 was loud. UP0 (Kazakhstan) was S9+ at 1416 and I found XW1 Laos, very rare from the eastern US.

“Conditions seemed the best at 1300Z, but I was running stations fairly well off and on thru 1515Z. This included two western Siberia area QRP stations. Signals from the Baltic states and Finland were louder than stations farther south at times. Again, 15 closed early to EU about the time the sun was setting on the EU side or even earlier. By 1800Z, most of EU had died out and the few stations north of the Med area worked were weak and fluttery.

“However, there was good activity to the south and several stations in the Carib/SA area were running with low numbers sent. I spent over an hour picking off new prefixes mainly to the south.

“At 2100Z, a few stations from Black Sea Russia and many Ukraine stations were back in along with Turkey, DL, YT, SP, HA, CT, F, 9A50 and I, which was not as widespread as Saturday. From 2133-2156 three weak JA Japanese were worked.

“After enjoying a nice steak I grilled, it was back on at 2300Z to finally find decent strength JAs, but activity was low. USA 6, 7, 9, 0s were all quite loud. In the last 25 minutes, E/SE Asia beyond JA started coming thru working BY5 in South China and very weak two QSOs with Eastern Malaysia and one Western Malaysia. It was a thrill to hear loud EU and work Asian DX again on 15 after a dreadful month of May with April not much better. The only areas not worked were southern AF (no activity?), Indonesia, and NE Asia west of JA. This was a huge improvement from what I expected.

“There was a good opening on 15 to Indonesia on June 4 from around 1230Z-1400Z or later. I logged 4 or 5 stations there all with good signals except one about S4 with the rarest being a YC6. This was the first time I have heard them on 15 since mid-April. Sporadic E has been rather poor so far, very few 10 meter openings that I have been able to catch.”

David Moore sent this article about coronal holes:

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 June 2 through 8 were 27, 0, 0, 0, 0, 12, and 15, with a mean of 7.7. 10.7 cm flux was 85.2, 83.2, 80, 79.1, 78.5, 78.5, and 80.1, with a mean of 80.7. Estimated planetary A indices were 4, 3, 4, 29, 26, 9, and 6, with a mean of 11.6. Estimated mid-latitude A indices were 5, 5, 5, 23, 21, 10, and 6 with a mean of 9.4.




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