The K7RA Solar Update


Solar activity increased over this past week, with the average daily sunspot numbers up 32 points to 81.6, while the average daily solar flux increased more than 16 points to 113.4. The geomagnetic field was active on March 29 due to solar wind. Sunspot numbers for March 28-April 3 were 49, 73, 70, 83, 84, 103 and 109, with a mean of 81.6. The 10.7 centimeter flux was 98.7, 105.1, 108.4, 113.3, 119.1, 122.1 and 127, with a mean of 113.4. The estimated planetary A indices were 9, 23, 17, 4, 6, 4 and 3, with a mean of 9.4. The estimated mid-latitude A indices were 10, 19, 12, 3, 6, 4, and 3, with a mean of 8.1.

The predicted solar flux is 130 on April 5-7, 125, 115 and 110 on April 8-10, 105 on April 11-12, 120 on April 13-14, 115 on April 15, 110 on April 16-17, 105 on April 18-19, 100 on April 20-21, 105 on April 22, and rising to 110 on April 23-24. The predicted planetary A index is 5 on April 5, 8 on April 6, 5 on April 7-9, 8 on April 10-12, 5 on April 13-22, then 12, 8, 18 and 15 on April 23-26, 5 on April 27-29, and rising to 8 for April 30-May 4.

Our three month moving average of sunspot numbers for January through March was 80.7. To review recent numbers, the three-month moving average of sunspot numbers centered on January, 2012-February, 2013 was 83.3, 73.7, 71.2, 87.3, 91.5, 96.5, 91.9, 89.9, 81.2, 82.3, 74.4, 82.8, 73.6 and 80.7.

Earlier this week, NBC ran an interesting report about modeling the Sun’s interior on a supercomputer.

Jon Jones, N0JK, of Lawrence, Kansas, reports: "I was in Hawaii the weekend of the CME impact on March 17. There was no significant VHF enhancement from the CME and geomagnetic propagation that day. If anything, conditions seemed worse on 6 meters. A day after the geomagnetic field started to settle down, propagation picked up. On March 22, the KH9/WA2YUN beacon was in again for about 5 hours, and I worked stations in Australia and FK8CP on trans-equatorial propagation around 0545 UTC. I was heard by BV2DQ in Taiwan. The KH9 beacon was back almost every evening until we left for home on March 23.”

Jim Smith, K3RTU, of Aston, Pennsylvania, sent in another report from the field where he was working DX from his backpack-based radio: “When I wrote in February, I mentioned that I had worked EA8BVP in the Canary Islands when I was operating from Ridley Creek State Park (FM29) in Southeastern Pennsylvania. Since then, I have made a number of good contacts from the same location, but on April 3, I hit the jackpot on 17 meters. From 2045 until 2124 UTC, I worked R7AY and SV2JAO on CW, and then I worked S57DX, W7FE and IK4GRO on SSB. Both R7AY and SV2JAO gave me 559 reports; I got a 5×6 from S57DX and a 5×4 from IK4GRO, but W7FE could barely hear me. To say the least, 17 meters was red hot. I finally had to pack everything up into my backpack and head back to the car, which was a mile away; with the temperature in the mid 40s, the wind chill that made it feel like it was 30. It’s hard to send CW when your fingers are stiff from the cold!”

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.