The K7RA Solar Update


Solar Cycle 24 continued its upward trend this week. The average daily sunspot number was more than double the value of the week before, rising from 50.9 to 114, while the average daily solar flux rose 44 percent, from 96.8 to 139.4. All this week through Tuesday, sunspot numbers and the solar flux kept rising and beating old numbers, and we had to look further and further back into Solar Cycle 23 to find comparable conditions. Sunspot numbers for March 3-9 were 71, 104, 114, 118, 122, 137 and 132, with a mean of 114. The 10.7 cm flux was 120.9, 126.8, 134.6, 142.5, 153, 155 and 143.1, with a mean of 139.4. The estimated planetary A indices were 12, 10, 5, 5, 10, 5 and 4, with a mean of 7.3. The estimated mid-latitude A indices were 11, 7, 4, 3, 7, 4 and 2, with a mean of 5.4.

On Tuesday, March 8, the daily sunspot number was 137. The last time the daily sunspot number was higher than this was July 7, 2005, when it was 149. Twice this week, the 10.7 cm receiver at Penticton was overloaded -- swamped by energy from a solar flare -- and the daily solar flux value had to be estimated. On March 7 and 8, the noon solar flux readings were 938.6 and 166.7; these were corrected by NOAA to estimated values of 153 and 155. The estimated flux level of 155 was the highest since July 23, 2004, when the solar flux was 165. On Thursday, March 10, the sunspot number was 88 and solar flux was 131.3.

The predicted solar flux for March 11-14 is 130, 130, 125, 125, then 120 on March 15-18, 100 on March 19-21 and then going below 100 until April 2. The predicted planetary A index for March 11-13 is 18, 12 and 10, then 5 on March 14-21, 7 on March 22-23 and 5 on March 24-26, then 7, 7, 19 and 7 on March 27-30. Geophysical Institute Prague predicts unsettled conditions on March 11-14, quiet to unsettled March 15 and quiet March 16-17.

Last week’s report of a South American 2 meter signal heard more than 4700 miles away in North Carolina provoked a number of expressions of disbelief from some folks very knowledgeable about VHF propagation. After exchanging e-mails with the fellow on the South American end, I’m not sure what happened. There are spotting lists showing the station on 10 meter FM that day instead of 2 meter FM, although our South American friend says he was on 2 meters at the time the transmission was heard. There is also a bit of a language barrier making some details unclear. One possibility is that the receiver in North Carolina picked up a 2 meter signal from a downlink from a 10 meter remote base station some distance away.

A new, slightly revised report of recent smoothed sunspot numbers along with predictions is out this week. You can compare this with the last time the same table appeared and note the slightly revised smoothed sunspot numbers from August 2010 through August 2011. The numbers are all slightly lower.

Randy Crews, W7TJ, of Spokane, Washington, posted an exuberant observation about the recent solar activity. He wrote: “During the ARRL International DX SSB Contest, 15 meters was smokin’ and I worked the first European and African Stations on 10 meters since the fall of 2004. The high bands just took on a completely different character. It looks as if this is the end of our long drought on the high bands. QST Technical Editor Joel Hallas, W1ZR, could not have better timed his article in the March issue regarding being ready for the expected surge.”

Jaap Verheul, PA3DTR, wrote to us from Zaltbommel, the Netherlands, about recent conditions: “I have experienced good conditions now for about five days in a row, no wonder -- now the solar flux is up and sunspots 1164, 1165 and 1166 are on the solar disk! I had much fun in the ARRL contest last weekend. Ffiteen meters was a thrill to work USA stations. But that isn’t all: I even found 17 meters open to the USA after dark on Monday evening! I worked W1GUE with 100 W and a dipole on CW. That has not happened for a long time. I am very interested in propagation on 30 meters and I often check this website. It shows a recent high-resolution map of Maximum Usable Frequencies (MUFs) for 3000 km radio signal paths. Today I found out that there is no contour present anymore for 10 MHz in the northern hemisphere. That doesn’t mean that the band is all-open, but from my location, the chances of propagation paths over 3000 kilometers is much better thanks to the new solar cycle and springtime conditions.”

I think instead of reflecting actual current MUF, the map is based on the latest predicted smoothed sunspot number for the month, which is currently 43.

John Shew, N4QQ, of Silver Spring, Maryland, reported excellent conditions during the ARRL International DX SSB Contest last weekend on 10 meters: “While CQing on 10 meters from W3LPL’s superb multi-op contest station Sunday morning -- with the beam pointed southeast around 1250 to attract Barazilians and other South Americans -- I was answered in quick succession by JA6WJL, JA6WIF and BV1EK -- all S9 signals on the long path. Another 10 minutes of CQs attracted no other long path stations, but a check of DX putouts indicate that the band was open long path until around 1330.”

You can get a nice view of the W3LPL antenna array here. Click on “Bird’s Eye” to get a detailed view -- zoom in and click on the compass to see images from different perspectives. You can also expand the image to the left by clicking on the left-arrow on the upper-left corner of the picture.

Roger Harrison, VK2ZRH, of Woollahra, New South Wales, Australia, noted the N4QQ comments recently about trans-equatorial propagation: “For the benefit of newcomers to TEP, I have two web pages -- afternoon TEP and evening TEP -- that each give a detailed introduction to afternoon and evening type TEP, written over 2006-2007 and posted in 2007.” Also, the Australian IPS Radio & Space Services has a PDF on TEP here.

During the 1970s, Harrison worked for seven years at IPS Radio & Space Services: “I was employed in the Low Latitude Research Section for part of that time, working for Dr Leo McNamara (author of Radio Amateurs Guide to the Ionosphere) on TEP. I also pursued my interest in sporadic-E, with the aid and encouragement of IPS colleagues.”

Pat Dyer, WA5IYX, of San Antonio, Texas wrote: “On March 3, I heard my first Argentinean station on 6 meters since August 2005. The 5 W LU7YS beacon on 50.085 was about 539 at 2215.  The LU7YS op himself made some TX and XE2 QSOs, but his CW signal had too much fading on it here for me to try a call.

“On March 2, we had a lot of mid-day and early afternoon 6 meter E-s to the southeast, and there had been hope that would link into the F2 that’s been creeping ever closer recently, as the rising solar flux and season get more favorable. A rule-of-thumb here has been a solar flux of 120-130 is a good level for 6 meter Argentineans in March and April. There was no direct evidence of any E-s involved in the March 3 event, though there is a lot of water in that direction for a linking hop to land in. March is statistically the worst month of the year for VHF E-s here, so that linkage is far more common in April as that season awakens.

“One of my pet peeves regarding the liberal use of TE/TEP to describe these modes: Our daytime 6 meter paths to Argentina are usually the result of a chordal F2 hop (no 1-hop ground reflection), exhibit normal fading and are designated F2F2 (vs F2-F2). The after-dark (‘classical TE’) is caused by a scatter mechanism in the F2 layer and is distinctive in its multi-path and flutter sound. One only has to hear the same-path stations by each mode to appreciate the difference (much pioneer work on this was done in Solar Cycle 19 with ZE2JV documenting it in QST articles).”

Bob Karpinski, WB8B, of Clinton Township, Michigan, sent in a report about using low power on 12 and 17 meters: “With the solar flux reaching 135, 12 meter propagation was unprecedented on March 6 with a lot of DX activity and big signals. The band was already opening into Europe and Africa around 1200, while ending with nice openings across the Pacific and into Japan. Propagation was so exceptional on 12 meter CW that I worked 11 DXCC countries using 1 W of output power and three active elements on a Yagi at 63 feet. The 1 W QRP contacts included M0DHO (Great Britain), LA0DX (Norway), VO1HP (Canada), PA1CC (Netherlands), 4Z4DX (Israel), G3RXP (Great Britain), GM3YTS (Scotland), SV1CQN (Greece), GW3YDX (Wales) , EI6IZ (Ireland), MI0BPB (Northern Ireland) and 6W2SC (Senegal). Additional 12 meter CW contacts were made with SV2BOH (Greece), CO8LY (Cuba) and PA3DTR (the Netherlands) at the 5 W level. Also, 17 meters has been providing excellent evening paths into the northwest, especially on March 6, when I logged a CW QSO with KL7J in Alaska using 1 W QRP around 2300. His signal was a very solid S9+30 dB, which ended my Sunday of contacts with 12 DXCC countries using 1 W of output power.”

Thanks, Bob!

“Mike Treister, W9NY, reported: “Operating W9NY from Dune Acres, Indiana this weekend, I was absolutely astounded by the band conditions on 15 meters (I only worked 15 meters for the ARRL SSB contest). It was like the good old days. Signals from Europe were often coming in 20 over 9, as were many from Japan. While running about 100 JAs late Saturday afternoon with my TH7 aimed in that direction, I kept having stations call me from Europe and South America off the side and back of the beam! I worked several European and Japanese stations who were running only 5-10 W (one British station was running 3 W), and they were all coming in Q5. I received numerous signal reports that I was well over the customary 5 by 9. I slept Saturday night and got up at 6 AM Sunday to see what was happening on 15, and was surprised to find the entire phone band packed with DX stations. This was the most fun that I have had during a contest in many years.”

Max White, M0VNG, of Worcester, England, sent an interesting article from NASA about some early history of sunspot observation.

Tim Goeppinger, K6GEP, of Orange, California, alerted us to a series of comics published this week that feature solar activity. From March 7-10, the comic strip Brewster Rockit is running the series.

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.