The K7RA Solar Update
Although solar activity is quite low, there was an increase in sunspot numbers and in the solar flux over the past week. The average daily sunspot numbers were up nearly 20 points -- about 36 percent -- to 74.1, while the average daily solar flux increased nearly 13 points to 108.7. Sunspot numbers for August 23-29 were 49, 69, 70, 78, 85, 73 and 95, with a mean of 74.1. The 10.7 cm flux was 96.7, 104.2, 105.9, 113.2, 111.5, 111.2 and 118.3, with a mean of 108.7. The estimated planetary A indices were 10, 9, 10, 11, 7, 4 and 4, with a mean of 7.9. The estimated mid-latitude A indices were 11, 9, 10, 10, 7, 3 and 5 with a mean of 7.9.
There was also quite a remarkable increase on Thursday (August 30) when the sunspot number jumped 23 points from Wednesday’s value to 118, and the solar flux was up nearly 10 points in one day to 127.8. Both of these numbers will figure into next week’s averages, as our reporting period is Thursday through Wednesday.
One new sunspot region appeared on each of the three days -- August 23-25 -- then three new regions appeared August 27, then one each on August 28-29, and three more on August 30.
The latest forecast has activity over the next week a bit lower than the forecast a few weeks ago, but somewhat higher sunspot numbers than the prediction in the August 30th edition of The ARRL Letter: The predicted solar flux is 130 on August 31-September 7, 115 on September 8, 110 on September 9-10, 105 on September 11-12, 100 on September 13-16, 95 on September 17-22, then 115 on September 23, 120 on September 24-25 and reaching 125 on September 26-28. The predicted planetary A index is 10 and 8 on August 31-September 1, 5 on September 2-7, 8 on September 8-9, 5 on September 10-14, 12 on September 15-16, 8 on September 17-18, 5 on September 19, 8 on September 20-21, 10 on September 22, and 8 on September 23-25, followed by 5 on September 26-October 4, and 8 on October 5-6.
OK1HH predicts quiet-to-unsettled geomagnetic conditions on August 31, mostly quiet September 1-2, quiet-to-unsettled again on September 3-5, quiet on September 6-8, quiet-to-unsettled September 9, quiet-to-active September 10-13, quiet September 14-15, mostly quiet September 16, quiet-to-active September 17-18, quiet September 19, mostly quiet September 20, quiet September 21-22, and quiet-to-active September 23.
We received a note from Ray Bass, W7YKN, of Sparks, Nevada, about how the HF bands don’t seem as good as they were during past solar cycles. Ray writes: “I’m only finding 10 meters open a little, and 20 real good once in a while and not like years past, or is my receiver broken?”
Although Solar Cycle 24 is predicted to peak between February-July 2013, solar activity in 2012 has been substantially below what it was toward the end of 2011; there isn't enough sunspot activity to sustain 10 meters, although fall should provide an advantageous seasonal variation for most paths. Currently, sunspot activity is stronger than it was exactly a year ago. Fifty-five days covers two complete solar rotations, and the 55 days from early July-August 29 had a daily sunspot number average of 87.2. On the same days last year, the average was 20 points lower, at 67.2.
We received reports of recent sporadic-e and tropo propagation on VHF. First, Jon Jones, N0JK, in Wichita, Kansas wrote: “There was a surprisingly good series of sporadic-E openings on 6 meters on August 24-26. On the evening of August 24, there were many double hop E-skip contacts made from W3 and W4 to California. Earlier, Central America was in to Colorado, Michigan and the Gulf Coast. From Kansas, I worked WA7JTM (DM33), WB7BBI (DM93) (short E-skip at 825 km, with a high MUF), K8OY (EM88), WB3BEL (FM18) and N4OX (EM60) on 6 meters. This opening was 28 days (one solar rotation) after the big 2 meter E-skip opening July 24. Perhaps a solar influence?”
Jon also wrote in a later message: “There was a strong tropo opening on Monday morning, August 27 from Northeast Kansas to Illinois, Minnesota, Nebraska and Wisconsin. I worked W9EWZ (EN52), KA0PQW (EN33) and KQ0J (EN11) around 1330 UTC on 144 MHz.”
Ken Tata, K1KT, of Warwick, Rhode Island, wrote on August 24: “Tropo has been quite good along the East Coast the last three nights. Last night, I went portable to Narragansett, Rhode Island to operate 2 meters. When I arrived, there was an onshore breeze. Despite that -- using an 11-element Yagi and 50 W -- the DX for the evening was in grid squares FM17 and FM16. I also heard the Cape Hatteras beacon, about 480 miles away. Everything I heard was coastal. Except for the beacon, most signals were in the S5-S7 range, with about 12 dB of fading signals. Signal levels improved up until 11PM local time, when I packed up and went home.”
Ken wrote later and said these three nights were followed by another three nights of good tropo activity.
Ken continued: “Since this wasn't a contest, activity was rather light, but even relatively ‘small’ stations did well and had fun! We need more activity on VHF/UHF. There are lots of rigs with 6 meter and 2 meter capability, and relatively high gain 2 meter antennas are not all that big. You can build a WA5VJB ‘Cheap Yagi’ for literally a few bucks. You can carry an assembled 11-element Yagi or 8-element Quagi for 432 MHz on the back seat of your car. Portable operation can be considerably easier and setup faster than for HF.”
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.