The K7RA Solar Update


The sunspot appearance reported last week seems to follow the pattern emerging for most of 2008. A spot will appear for one or two days and then suddenly it is gone. Last week's report mentioned the solar wind being at an all time low. This week, NASA announced that so far, 2008 is the "blankest year of the space age," with more than 200 spotless days. The minimum following Solar Cycle 18 in 1954 had 241 days without sunspots, and it preceded the solar max in 1959 for Solar Cycle 19 that had the highest sunspot numbers on record.

Sunspot numbers for September 25-October 1 were 0, 0, 0, 0, 0, 0 and 0 with a mean of 0. The 10.7 cm flux was 68.2, 67.7, 67.3, 67, 66.8, 66.2 and 65.8 with a mean of 67. The estimated planetary A indices were 4, 4, 2, 3, 2, 4 and 6 with a mean of 3.6. The estimated mid-latitude A indices were 1, 2, 1, 2, 2, 3 and 7 with a mean of 2.6.

With September now gone, we now can calculate the 3-month average of sunspot numbers centered on August, which was 1.1. Compare that with 3-month averages going back to June 2006:

Jun 06 28.9
Jul 06 23.3
Aug 06 23.5
Sep 06 21.2
Oct 06 24.1
Nov 06 23.1
Dec 06 27.3
Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Jun 07 18.7
Jul 07 15.4
Aug 07 10.2
Sep 07 5.4
Oct 07 3
Nov 07 6.9
Dec 07 8.1
Jan 08 8.5
Feb 08 8.4
Mar 08 8.4
Apr 08 8.9
May 08 5
Jun 08 3.7
Jul 08 2
Aug 08 1.1

Randy Crews, W7TJ, of Spokane, Washington, commented that extended periods of quiet Sun make propagation more predictable, but zero sunspots affect all bands, not just 15 meters and higher frequencies; even 80 meters is different. After sunset, when residual ionization from the sun is gone, 80 meters suffers. He believes we are seeing a double bottom (October 2007 and now), following the double peak of Solar Cycle 23.

Two weeks ago, on September 19, Michael Reid, WE0H, of St Francis, Minnesota, mentioned his experimental operation on 600 meters (500 KHz) as WD2XSH/16. Mike said the low solar activity and quiet geomagnetic conditions make this part of the spectrum quite attractive for long distance propagation. During the previous week, he and other FCC Part 5 experimental stations were beaconing and getting reports from all over, typically 1000 miles distance.

Early last Friday (September 26) morning, George Hrischenko, VE3DGX, of Zephyr, Ontario, noticed a number of UHF and high VHF (175-220 MHz) television stations coming in from a long distance away. He didn't say where the signals were from, but figures it must be from ducting.

In response to last week's mention of noctilucent clouds and UHF propagation, Ken Beck, WI7B, of Kennewick, Washington, sent a copy of the scientific paper by Bellan referenced in the article in Science Daily, published in the Journal of Geophysical Research, vol 113, D16215. He notes the article mentions propagation from 50 MHz to 1 GHz, so this may be a useful propagation mode for 6 meters as well. Click here to read an abstract of the article and note there is a link on that page providing access to the full article.

Patrick Dyer, WA5IYX of San Antonio, Texas, sent a link to a 1968 article in Soviet Life about noctilucent clouds and experiments run by a Latvian teenager. Read it here.

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.