The K7RA Solar Update


No sunspots appeared this week, although there were hopeful signs. reported on October 11 that a new sunspot was "struggling to emerge," but it faded quickly, and the Sun has been blank since then. Sunspot numbers for October 8-14 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 68.8, 69.2, 70, 70.4, 70.1, 69.8 and 70.9 with a mean of 69.9. The estimated planetary A indices were 2, 3, 2, 6, 2, 2 and 2 with a mean of 2.7. The estimated mid-latitude A indices were 1, 1, 0, 7, 1, 2 and 0 with a mean of 1.7. For this week, expect more of the same quiet geomagnetic conditions. Geophysical Institute Prague expects quiet to unsettled conditions today, October 16, then quiet conditions October 17-22. NOAA and US Air Force predict the planetary A index for today at 7, then back down to 5 for the foreseeable future. They expect solar flux to be up to 72 today through October 30.

We got a nice response from Dr Joseph B. Gurman, Project Scientist on the NASA Solar Terrestrial Relations Observatory (STEREO) regarding observing sunspots on the far side of the Sun: "Those bright spots are indicators of magnetic activity, which may or may not be associated with sunspot groups. The bright areas you see, called 'plage' (pronounced 'plahj') in the solar physics business (thanks to some solar astronomer of yore who thought they looked like white-sand beaches, 'plage' being French for beach), represent areas higher in the solar atmosphere than the visible surface of the Sun where (1) magnetic fields are stronger than in their surroundings, and (2) material has been heated to higher temperatures than in their surroundings.

"The two appear to go together, somewhat paradoxically when one considers that only a few hundred km lower in the atmosphere, sunspots are cooler than the surrounding photosphere. Plage is a feature of both active regions with sunspots ('sunspot regions') and active regions without visible spots. Indeed, in the coronal extreme ultraviolet (EUV) lines (Fe IX, X; Fe XII; Fe XV) in which the STEREO images are obtained, we call anything of a certain size and that bright that persists for hours to weeks an active region, regardless of whether NOAA has assigned it a number. If there are no spots, it may be 'old plage' from a region whose spots have disappeared, a new region that will eventually produce spots or a modest active region that never shows more than tiny 'pores' (spots without penumbrae), that are sometimes very difficult to see from the ground."

We also heard from William Thompson of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who wrote "No, we can tell if there's an active region or not, but we can't determine from the EUVI data alone whether that active region will have a sunspot." Dr. Gurman also mentioned checking magnetic maps of the Sun from the ground based GONG network (Global Oscillation Network Group) and animations of solar magnetic activity. What I currently see using these tools is very little magnetic activity.

Robert Brock, K9OSC, of Fridley, Minnesota, expressed some frustration trying to install the free propagation prediction program W6ELprop on a PC running Microsoft Vista. This suggestion ran in this bulletin back in 2007, and the key is to be sure you are logged in to the PC as Administrator, then from Windows Explorer right-click the installation file, and from the drop-down menu select "Run as Administrator." This is just an annoyance caused by security features in the operating system. I haven't tried Windows 7, which is due to be released this week, but probably similar steps will be needed.

In the April 24 and May 1 from earlier this year, we mentioned WSPRnet, the Weak Signal Propagation Reporter Network that looks to be a promising tool for looking at HF propagation. The October 2009 issue of CQ Magazine has an interesting interview with Nobel Laureate Dr Joe Taylor, K1JT, the developer of WSPRnet and other weak signal signaling methods. You can read it online here. Also, Steve Nichols, G0KYA, gave a talk on WSPR at the recent Radio Society of Great Britain (RSGB) convention. You can download his excellent PowerPoint presentation here. If you don't have PowerPoint, part of the Microsoft Office suite, you can download a free PowerPoint viewer here.

After recent items in this bulletin about VHF propagation and fog banks, Len Halvorsen, WA2AMW, wrote: "The comments from Alan, KI6HPO, reminded me of an article I read many years ago about a VHF/UHF propagation enthusiast in Hawaii who would search for (Tropo?) Propagation Ducts to the mainland by driving up the side of the volcano (the access road to the observatory telescopes) and stopping at various altitudes to test for existing propagation conditions to the West Coast. He would often find paths to the mainland that were open only from within a narrow band of altitude on the side of the volcano. Above and below that band, the propagation corridor did not exist, nor was it accessible from his mobile/portable equipment."

Carson Haring, AC0BU, of Corydon, Iowa, says he was surprised to see VHF fog propagation a subject of discussion because he assumed it was common knowledge: "Here in southern Iowa, where I work removing trees under the power lines from before the Sun rises, I very often have assumed that fog influences propagation on 2 meters. Many summer mornings --from the time we get to the work site until the fog burns off, maybe 9 or 10 AM -- I can reliably use 2 meters for long-distance QSOs from my bucket truck mobile."

Also commenting on KI6HPO was Jug, WA6MBZ, of Santa Barbara, California, who wrote, "Until he died, we had an American who had been an AT&T employee who retired, then moved to San Quentin, Mexico, about 250 miles below the US-Mexican border. Every year for many years during the summer months, he would come on the Santa Barbara repeater on 146.790 MHz. He knew when the signal level was right, and therefore when he could, he would get into our repeater with a usable signal. Our repeater is located on a hill near the beach called The Mesa. It is at about 400 feet above sea level. He could not get into our other repeaters that were located up at about 4000 feet. He was a very friendly guy and we used to talk to him for hours on end. I don't think any of our group ever asked him if he could get into other repeaters along the coast of Southern California." Thanks, Jug!

Also coming in this week were 6 meter sporadic-E reports. Jon Jones, N0JK, reported from Kansas on Saturday, October 11 that he saw double-hop e-skip on 6 meters to beacons in Costa Rica, Bahamas and Florida. That same evening, October 12 at 0200 UTC, he worked WA4GPM in FN11 and N2LID in FN12 on 6 meters. On 10 meter CW on October 11, 2217-2236 UTC, he heard TX4SPA working N0RR, N4KG, KF6JOQ, W6QE, K1ZZI, KT4MM and W7DO.

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 in The ARRL Letter. Check 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.