Register Account

Login Help


The K7RA Solar Update


Although the average daily sunspot numbers are lower -- down nearly 13 points to 91.7 -- the average daily solar flux is higher by 6.7 points, rising to 122.2. Yes, solar activity is rising rapidly. You could see it coming earlier this week by glancing at the STEREO mission when you looked at the back side of the Sun. There was lots of activity, and you can still see quite a bit more (those white patches) just over the eastern horizon, which is on the left side of the image beyond -90 degrees. Sunspot numbers for September 8-14 were 47, 65, 77, 94, 97, 118 and 144, with a mean of 91.7. The 10.7 cm flux was 110.1, 111.8, 116.2, 121.3, 123.9, 129.4 and 142.6, with a mean of 122.2. The estimated planetary A indices were 4, 36, 33, 9, 27, 17 and 4, with a mean of 18.6. The estimated mid-latitude A indices were 2, 13, 20, 8, 17, 11 and 5, with a mean of 10.9

The image of the daily Sun shows a disc peppered with sunspots, a welcome sight after watching the current solar cycle seem to stall. Numerous CME events disturbed the Earth’s magnetic field. The planetary A index record shows September 9, 10 and 12 were the most active days, with the index at 36, 33 and 27. The autumnal equinox in the northern hemisphere is just a week away: September 23 at 0905 UTC, which is 5:05 AM EDT or 02:05 AM PDT. Luckily, the increased sunspot activity should continue.

The updated prediction for solar flux and the planetary A index from USAF/NOAA sure changed from Wednesday to Thursday. Solar flux is predicted to be lower than earlier thought and planetary A index higher. Wednesday’s prediction had solar flux at 145 on September 15-17, and 150 September 18-22. On Thursday, September 15 the actual solar flux was 140.7. Thursday’s forecast has solar flux at 140 on September 16-17, 135 on September 18-19, 130 on September 20, and 125, 120, 120 and 110 on September 21-24, and 115 on September 25-29. The predicted planetary A index is 10, 20 and 15 on September 16-18, 5 on September 19-23, 7 on September 24-25, 5 on September 26-29, and 15 on September 30. You can compare the September 14-15 forecasts here. Geophysical Institute Prague predicts quiet conditions September 16-17, quiet to unsettled September 18, active on September 19, quiet to unsettled September 20 and quiet again on September 21-22.

Ed Richmond, W4YO, of Harbor Island, South Carolina writes: “I usually live on 6 meters during the summer sporadic-E season. The propagation went downhill at the end of August, and I more or less quit the band. But on September 9, I noticed some spots on the DX reflector of an opening into northwest South America, and decided to take a look. I heard an S9+ signal on CW and thought it might be a local. When he signed as HK7AAG (Columbia), I nearly fell off my chair. I called and worked him, and about two minutes later, heard HC1HC (Ecuador), not as loud, but copyable. I called and worked him, too. A few minutes later, I worked YV5ZV in Caracas. I had not expected any of this, since September has statistically the lowest incidence of sporadic-E propagation. The whole thing is even more amazing because I live in a CC&R neighborhood and my 6 meter antenna is a dipole mounted about 35 feet high in the attic. I’m always amazed at what I have been able to work with that antenna in four years on 6 meters. Of course, my location helps, too. I live on Harbor Island (EM92sj) -- 14 miles out from Beaufort, South Carolina -- on a barrier island. My QTH is right on a salt marsh that looks out on the Atlantic Ocean. I will continue to check 6 meters for some TEP this month. Hope I get lucky.”

Thanks, Ed!

Scott Bidstrup, TI3/W7RI, of Costa Rica sent an article from New Scientist that suggests that a big enough CME could deposit radiation in low earth orbit that could persist for decades. Scott wonders if there would be a long lasting effect on radio propagation.

Mike Schaffer, KA3JAW, of Tampa, Florida (EL87) monitors television broadcasts across Central America via sporadic-E. On September 10, he wrote: “This morning at 1436, I received a analog NTSC broadcast from Televisora Nacional, TVN-2, HOU in Panama City via sporadic-e at a distance of 1320 air miles. On October 9 at 2110 on September 9, F2 propagation was noticed on NTSC analog channel 2 coming from due south from South America. The first thing I noticed was what appeared to be a out-of-phase sporadic-E taking place, but the video would not sync lock, even though the signal was at moderate signal levels with only light fading. Then the video appeared with warped diagonal, horizontal and vertical scroll bars. The audio was almost non-existent-to-weak, with multi-path distortion that produced a fair amount of scatter reflections. The audio was so muffled that the TV mono speaker was not good enough. To correct this effect, I used stereo headphones. What struck me was that the Spanish audio dialect was not what I am accustomed to hearing from other DX propagation modes from Mexico, Central America countries or northern coast of South America.

“At 2135, the F2 storm had peaked at my location. At this point, I performed a manual channel scan on all VHF low, high, and UHF 14, 15 and 16 channels. The results indicated the maximum usable frequency did not exceed the audio carrier at 59.75 MHz. At 2203, the storm declined to a moderate state. I then saw a weak Spanish black-and-white video program that lasted for perhaps five seconds. I would suspect that it was either coming from Quito, Ecuador at 1950 miles away or Lima, Peru at 2779 miles away, because the bearing to both cities from my location is at 171 degrees in azimuth. Minimum F2 single-hop paths can start roughly 2000 miles and reach a maximum of up to 3000 miles. At 2223, the F2 geomagnetic storm rapidly faded back to normal conditions.”

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.



Instragram     Facebook     Twitter     YouTube     LinkedIn