ARRL

News

The K7RA Solar Update

08/12/2011

The average daily sunspot numbers declined more than 24 points to 75.1 this week, while the average daily solar flux was down more than 12 points to 104.3. We saw solar flares recently, with a substantial geomagnetic upset on Friday and Saturday -- August 5-6 -- when the planetary A index was 49 and 31. The largest solar flare of the current sunspot cycle, an X7 flare, occurred at 0805 UTC on August 9, emerging from sunspot group 1263. This does not appear to be Earth-directed.

Sunspot numbers for August 4-10 were 81, 94, 85, 89, 80, 54 and 43, with a mean of 75.1. The 10.7 cm flux was 116.3, 109.4, 110, 105.4, 101.5, 97.5 and 90.3, with a mean of 104.3. The estimated planetary A indices were 4, 49, 31, 7, 10, 9 and 7, with a mean of 16.7. The estimated mid-latitude A indices were 3, 32, 14, 6, 8, 5 and 8, with a mean of 10.9.

The latest forecast from NOAA has solar flux at 85 through August 17, then 90, 98, 98 and 100 on August 18-21, and then 105 on August 22-30. The planetary A index is expected to be 7 on August 11, 5 on August 12-15, then 15, 18, 10, 8, 5, 12 and 8 on August 16-22, 5 on August 23-25, and 15, 10, 8, 5 and 5 on August 26-30.

Reviewing recent sunspot activity, there were four sunspot groups visible on August 4: 1260, 1261, 1263 and 1266. The total area covered by sunspots was 1380 millionths of a solar hemisphere, the largest coverage since March 8, 2011. On August 5, new sunspot group 1267 appeared, and on August 6, groups 1260 and 1266 disappeared and new group 1268 arrived. On August 7, 1268 disappeared and 1266 reappeared, and on August 8, 1261 was gone and 1268 emerged again, only to vanish on August 9. On August 10, sunspot group 1267 was gone, and 1268 came back. On August 11, sunspot group 1263 was gone, and new groups 1269 and 1270 appeared.

Kent Doucey, N0IRM, of Galena, Missouri, was on 20 meters SSB on August 3 and worked Victor, E51CG on Rarotonga at 0239. The signals were strong, so they switched to 10 meters and connected again, this time with weaker but quite readable signals, at a distance of about 5900 miles.

Jeff Hartley, N8II, of Shepherdstown, West Virginia, wrote on August 6: “We had some nice sporadic-E on the evening of Wednesday, August 3, with 6 meters open to W9/0. I very briefly worked WA2BEV in Butler, Pennsylvania on 10 meters, only about 190 miles away via E-skip and logged a couple of Michigan stations there, possibly the result of the flares. Conditions were decent, with very good propagation to Australia and long path into South Africa on 20 meters around 1200. I then went up to 15 meters to find ST0R on CW. They were about S4 here and not workable thru the EU/JA pile up -- in 15 minutes, they did not work any North American stations). Returning after 1500, I luckily found their QSX frequency and was the next QSO, with the ST0R signal up to about S6. I then tried 12 meters and worked PA1CC and CS2W on CW. A listen on 10 meters yielded hearing an I0 beacon and hearing IW0 working someone not audible, but CQs yielded no QSOs. Signals on 15 meters in the 1500 hour were good up to Lithuania and Sweden, but I heard nothing from Russia.

“Regarding the comments made by Vince, W7FA, in last week’s Solar Update about solar flare/storm enhancement of signals, this is definitely true, even sometimes over polar paths. But another factor -- time of day -- would explain a big difference in signal strength; his SSB QSO with ST0R in the 2300 hour was at a time when signals would be expected to be much weaker than approaching West Coast sunset around 0200.”

Robert Elek, W3HKK of Johnstown, Ohio, is excited about 6 meters: “There was a huge 6 meter E-skip opening from Central Ohio to New England and the Maritimes this Sunday morning (August 7) around noon, with signals the strongest I’ve heard all season.  Mick, W1JJ -- with his box 9 el Yagis on a cell phone tower -- took my S-meter to unparalleled heights -- 40 dB over! And Roger, VE1SKY, and I had what seemed like a one hour armchair rag chew on a variety of topics, while the S-meter rolled between 20 over and S7. There are a lot more folks getting into meteor scatter with the WSJT software as a way to use 6 meters in the ‘off-season.’ I then worked a couple of 59+ signals from the New York City area, which is very short E-skip, indicative of intense sporadic E ionization. I even heard stations to my west while beaming east-northeast. As I rotated the 5 el Yagi to the west, they dropped out, so I was hearing S3-4 signals from behind me, also bouncing off the same sporadic-E cloud (backscatter) that was propagating signals so well from New England. Incredible!

“Two days earlier, on Friday night between 6-7:30 PM (local time), I made my first aurora QSO ever on 6 meters, and then 23 more into Michigan, Ontario, Wisconsin, Minnesota, Illinois, Iowa, Pennsylvania, Maryland, Virginia, Kentucky, Tennessee and Ohio. Strangest of all, the buzz-saw sounding CW notes came from Steve, KA1VHF, located a mere 20 miles west of me. We’ve worked each other a few times, but this was the first time via aurora! Two days before that, on Wednesday around 1430, I added G8BCG, G4RRA and CU2JT to the grid square collection for this season. So what a week it was! DX, E-skip the loudest of the season and aurora! Six meters ain't dead yet!”

Thanks, Robert!

Earth is currently moving through debris from the comet Swift-Tuttle, giving us the Perseid meteor shower, which should peak August 12-13.

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.



Back