The K7RA Solar Update


The average daily solar flux was down this week about 4 points to 113.4, while the average daily sunspot numbers were down 6.7 points to 65.4. The geomagnetic indices were very low and stable, which should please 160 meter operators who are also enjoying the long periods of darkness in the northern hemisphere. Sunspot numbers for December 20-26 were 53, 55, 67, 90, 53, 58 and 82, with a mean of 65.4. The 10.7 centimeter flux was 114.1, 114.6, 115.3, 114.2, 113.1, 113 and 109.8, with a mean of 113.4. The estimated planetary A indices were 6, 4, 1, 2, 3, 3 and 3, with a mean of 3.1. The estimated mid-latitude A indices were 7, 3, 1, 2, 2, 2 and 2, with a mean of 2.7. 

The predicted solar flux from NOAA and USAF call for 110 on December 28-30, 115 on December 31-January 4, 105 on January 5-7, 110 and 115 on January 8-9, 120 on January 10-12, 115 in January 13-19, and rising to 120 on January 20-22. The predicted planetary A index is 8 on December 28-29, 5 on December 30 through January 12, 10 on January 13, and back down to 5 on January 14-25.

Jeff Hartley, N8II, of Shepherdstown, West Virginia, wrote with some observations: “On Monday, December 17, I got up early to find UA0ZN (in Zone 19) on 80 meters, and finding not much else, I decided to call CQ. This resulted in a run of Japanese stations around sunrise, most of which were very good copy. I ended the run with a JA5 who was S9+10dB! It was one of the best openings to Japan that I have ever heard from here and my biggest ‘run.’ Signals from all over Australia were booming in on the Southern Cross net on 14.2385 MHz around 1300, and 12 meters was wide open to Central and Western Europe, with a few Southern Europeans on 10 meters. VR2XMT was S7 on long path on 12 meters around 1330Z.

“I finally had some spare time on a decent sunny day (Sunday, December 23) so I fixed my 160 meter sloper feedline. It still needs some work, but it is working like a champ! With 200 W, I was getting through to European stations Sunday night with ease. I worked UX0ZA, another Ukrainian station, SM6MCW, two British stations, DJ2EH (S9+), another German station, F6 (S9), OE5O, OK1DQT, OM2XW and ON4IA (S9+). I also heard 9K2MU, who had many US stations calling him that he could not hear. He was mainly working Europe and calling CQ. Sunday morning was rather poor on 12 meters, with some Western European contacts and a loud Norwegian station. Ten meters was pretty close to dead, but there were a few Western US stations on in the afternoon. But 17 meters was wide open to Europe with good signals, whereas they would have been much weaker with higher solar flux index.”
Randy Crews, W7TJ, of Spokane, Washington, thinks we are past the peak of Solar Cycle 24. He writes: “It’s pretty evident to me that unless we see another re-generation of new sunspots, November 2011 will be the peak of Solar Cycle 24 (short as the activity was) as [actual] solar activity as defined by average monthly sunspots and solar flux. Both measures have been slowly on the decline since that date. Then we will all have to prepare for the coming ‘Propagation Winter.’”

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.