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The K7RA Solar Update


The weak solar activity continues: The average daily sunspot numbers for the seven days of August 16-22 were down 23 points -- 30 percent -- to 54.6, while the average daily solar flux dropped a little over 16 percent -- 18.7 points -- to 96. These figures offer a comparison between August 9-15 and the latest reporting period of August 16-22. Sunspot numbers for August 16-22 were 34, 42, 56, 69, 52, 64 and 65, with a mean of 54.6. The 10.7 cm flux was 98.3, 95.1, 97, 96.2, 96.2, 94.2 and 94.8, with a mean of 96. The estimated planetary A indices were 11, 10, 11, 12, 12, 7 and 6, with a mean of 9.9. The estimated mid-latitude A indices were 10, 11, 11, 10, 11, 7, and 6 with a mean of 9.4.

Solar flux is expected to rise above 100 soon, with predicted flux values from NOAA/USAF at 100 on August 24-25, 105 on August 26-27, 110 on August 28-29, 115 on August 30, and peaking at 130 on August 31 and September 1. The prediction shows September 2 with a flux value of 125, then 120 on September 3-5, 115 on September 6-8, 110 on September 9, 105 on September 10, then dipping below 100 on September 12-15. The next peak is expected in the three days following the autumnal equinox, with flux values at 135 on September 23-25. The predicted planetary A index values are 5 on August 24-25, then 10 and 8 on August 26-27, then 5 again on August 28-September 7, and 8 on September 8-9, then 5 on September 10-14, then 12 on September 15-16, 8 on September 17-18, and back down to 5 again through the end of September.

OK1HH predicts the geomagnetic field will be quiet-to-unsettled on August 24-25, quiet-to-active on August 26, mostly quiet on August 27-28, active-to disturbed on August 29, quiet on August 30-31, mostly quiet on September 1, quiet-to-unsettled September 2-4, quiet on September 5-7, mostly quiet on September 8-9, quiet-to-active September 10, quiet on September 11, quiet-to-unsettled September 12, quiet on September 13, and quiet-to-unsettled September 14-15. reports that “the Sun’s x-ray output has nearly flatlined.” Click here for readings from 12 years ago, in the summer of 2000. Now compare those numbers with recent x-ray activity. The daily x-ray background flux is shown in the fourth column to the right of the daily sunspot number. Here is the x-ray flux shown in a graph for the past few days. The letters and numbers in the x-ray flux column in the previous two pages correspond to the values on the right side of the graph on the last page. Looking back in March, May, July and September of 2000, you can see higher numbers indicated by the letter C, but nothing at that level recently. The background x-ray flux is a good indicator for the level of energy from the Sun charging the ionosphere. The more the ionosphere is energized, the higher the MUF, or Maximum Usable Frequency is in general, although the MUF varies considerably according to time of day, season, and the end-points of the path under consideration.

Larry Godek, W0OGH, of Gilbert, Arizona, wrote on August 23: “Wow! Is it ever all over the place today. To start with, we had a short opening on 6 meters down to TG9 (Guatemala). Then I went up to 20 meters to put in some time doing the WSPR thing; 2 W to a 4 element Yagi up 30 feet is all I use on 20. In the time frame after my transmit cycle, I had reports from LA9, VE6, YV4, VK2 and KL1, plus other places around the US. The beam was pointed to about 45 degrees (northeast). What good is a beam doing you if your signal is going every which way? Watching the WSPR map showed a lot of good long haul signals.”

Editor’s note: The WSPRnet map Larry speaks of is can be found here. Note that you can select which band you want to observe in a drop-down menu below the map.

“When I worked the TG9 station on 6 meters, the beam -- which is atop the tower with the 20 meter beam -- was also pointed off to the northeast. That’s where his signal was strongest. Working 40 meters today around 2 PM (Arizona time), the band got really noisy with interference. Signals were still good though and then the interference went away. Since then, signal strength has swung all over the place; not slow drawn out fading, but fairly quick acting changes. This morning on 40, we had real short propagation to the southeast part of the state, no more than 150 miles. Then it swung around to where normal east-west signals became more prominent and the fellows southeast of here were out of the picture. I’d suggest folks take a look at that WSPRnet map when they go looking for DX. While it doesn’t show every country on the air, you can at least get an idea of where propagation is good toward.”

Thanks, Larry!

Jon Jones, N0JK, of Wichita, Kansas, had a comment in response to Randy, W7TJ, in last week’s Solar Update: “My opinion is that Solar Cycle 24 will probably be a two-peak cycle. The first peak was fall of 2011; the second peak hopefully spring of 2013. I agree with Randy -- enjoy the propagation this fall and spring of 2013. This may be as good as it gets on 10 meters and 6 meters for many, many years.”

John Van Dalen, N7AME, of Everett, Washington wrote: “I have to agree with Randy Crews, W7TJ, of Spokane. The DX activity for the Seattle area has been dismal. I only have small windows to operate right now and they are 0200-0400 UTC each evening and most weekends. I look at the spotting sites on the Internet, and Europe and Russia are having a great time, as is most of the East Coast. Oh, for a Solar Cycle like 22 or 23.”

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.



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