ARRL

News

The K7RA Solar Update

01/25/2013

The average daily sunspot numbers this past week dropped nearly 73 points to 56.4, while the average daily solar flux declined nearly 47 points to 110.7. The average geomagnetic indices were up about 50 percent, but it was still very quiet. The difference was mostly due to events on January 17 when the planetary A index was 13 -- higher than in recent weeks, but still moderate. The cause of the mild disturbance was the arrival of a coronal mass ejection (CME).

Sunspot numbers for January 17-23 were 74, 56, 46, 48, 50, 53 and 68, with a mean of 56.4. The 10.7 centimeter flux was 122.7, 115.2, 106.7, 106.6, 108.3, 110.3 and 104.9, with a mean of 110.7. The estimated planetary A indices were 13, 9, 7, 9, 4, 1 and 1, with a mean of 6.3. The estimated mid-latitude A indices were 12, 7, 9, 8, 4, 1 and 1, with a mean of 6.

The predicted solar flux from the January 24 forecast from NOAA and USAF has the 10.7 centimeter flux values at 100 on January 25-26, 95 on January 27-30, 100 on January 31-February 1, 110 on February 2, 120 on February 3-4, 125 on February 5-8, 120 on February 9-14, 115 and 110 on February 15-16, and back down to 105 on February 17-18. It doesn’t look like a return to solar flux values around 170 -- where it was on January 9-12 -- is expected any time soon. But those high levels earlier in the month weren’t predicted, either.

Looking back, a flux reading of 135 was predicted for January 9 in the November 25-December 9 daily forecasts, then downgraded to 110 on December 10-16, then increased to 115 on December 17-30, downgraded to 105 on December 31 through January 2, increased to 115 on January 3, 135 on January 4, 130 on January 5-6, 145 on January 7, and 150 on January 8. The final result? On January 9, we saw 169.3, far above any of the predictions over the previous 45 days, which were revised eight times. The forecasts are issued daily, usually after 2100 UTC, and posted here.

The predicted planetary A index from the same January 24 forecast is 8, 15, 20 and 12 on January 25-28, 5 on January 29-February 8, 8 on February 9-10, 5 on February 11-18 and rising to 8 on February 19. The January 25-28 levels are higher than predicted a day earlier, January 23. In that earlier forecast, the planetary A index for those same four days was 8, 8, 5 and 5.

Jeff Hartley, N8II, of Shepherdstown, West Virginia wrote: “It has been a pretty boring winter for DX. I did work four VK3s in a row from 2225-2255, including one mobile who was S6, and a QRP on 20M SSB long path on Thursday (January 24), so that path was very good. Twelve and 10 meters seemed dead at that time, and I only heard South America on 15 meters. I didn’t hear any European signals on 160. But, if the K index stays low, the lower flux should help the CQ WW 160 Contest this weekend.”

Unfortunately, the forecast for this weekend has some geomagnetic activity, with the planetary A index on February 25-27 at 8, 15 and 20.

On January 19, Jeff wrote: “Friday morning, January 18, I had a chance to operate and had some very strong signals on 10 meter phone from the UK, with small stations mostly S7-9. Even 5 and 10 W stations were good copy. This was starting about 1330 and the European opening ended after 1600. I worked Poland, Germany, Ireland, England, Scotland, then later the Netherlands, Belgium and France; German stations were about the only ones left at 1610. Friday evening was noticeably better than all this past week, but did not get to the radio until 0040. At that time, 15 meters was in good shape to Japan. I heard BW2AK in Taiwan, and 9V1YC in Singapore was about S3-4, and easily workable through a pile up.

“The HA DX contest started at 1200 Saturday with lots of European and Russian activity. From my location, I find that Russians are usually only easy to work very early in the day on 20, and almost impossible on 15 and higher. At 1315 when I started through 1430, the Russian stations had good signals on 20 meter CW, but there were deep rapid fading signals, making copying dits -- and sometimes whole letters and numbers -- very difficult. I worked about three UA9s, and I found UN2E about S3, plus quite a few from UA3, about four from UA4 and even some loud ones near St Petersburg in UA1. The deep QSB was even a problem on signals as close as Germany, as well as Hungary. YE1ZAT in Indonesia called in around 1545 with a good signal. Fifteen meters was open pretty well to Europe, but 10 was barely open at all to very Southern Europe.

In the afternoon, I briefly operated in the NAQP phone contest before heading off to work. At 1835-1900, 10 meters had a good number of loud signals, with one VE6 hitting 30 dB over S9. I worked a lot of Utah stations, as well as stations in Colorado, Arizona, Washington, Idaho, Montana and New Mexico. Fifteen meters was wide open to Texas, but there was a bit of a struggle to work West Coast stations, as Midwest stations beat me out consistently.”

Don’t miss “The Penticton Solar Flux Receiver,” an article on pages 39-46 in the February 2013 issue of QST. This gives a great explanation about where the solar flux numbers in our bulletin originate. It answered questions I had about the process, such as how they handle readings that go off the scale during a space weather event [Editor’s note: You must be an ARRL member and logged in to the ARRL website to read this article].

All times listed are UTC, unless otherwise noted.

Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.

 



Back