The K7RA Solar Update
This week we saw another one of those fast-disappearing sunspots -- it lasted just two days, over the last day of August and the first of September. No other sunspots were observed during the month of August. Sunspot numbers for August 27-September 2 were 0, 0, 0, 0, 12, 12 and 0 with a mean of 3.4. The 10.7 cm flux was 67.7, 67.9, 68, 67.2, 68.3, 69.1 and 68.2 with a mean of 68.1. The estimated planetary A indices were 5, 2, 2, 19, 5, 4 and 3 with a mean of 5.7. The estimated mid-latitude A indices were 4, 2, 2, 12, 5, 2 and 2 with a mean of 4.1.
The monthly average of the daily sunspot number, January-August 2009, is 2.8, 2.5, 0.8, 1.3, 4, 6.6, 5.1 and 0.4. The three-month moving averages of daily sunspot numbers for October 2008-July 2009 were 4.5, 4.4, 3.6, 2.2, 2, 1.5, 2, 4.2, 5.2 and 4. This takes into account all the daily sunspot numbers for September 2008-August 2009, and those numbers are for the center months of each of those three month moving average periods.
The latest figure -- for July 2009 -- is an arithmetic average of all daily sunspot numbers for June-August. The previous figure -- for June -- is an average of daily sunspot numbers for May-July. In other words, sum all the daily sunspot numbers from May 1-July 31, and that equals 478. Divide by 92 -- the number of days in those three months -- and it equals approximately 5.196, or 5.2 rounded off. For June and July we saw the moving average drop from 5.2 to 4, and if September has no sunspots after the one on September 1, then the three-month average centered on August will be 2. So what is coming up in the near term? Continued low solar flux and possibly no sunspots. Geophysical Institute Prague predicts quiet to unsettled conditions for September 4 and 8.
We received many tips and comments this week about the lack of sunspots, and a link to an article titled "Are Sunspots Disappearing?" It concerns the work of Livingston and Penn at the National Solar Observatory in Tucson and their observation that magnetic fields from sunspots are declining. It is important to note that most of their measurements are after the peak of Solar Cycle 23, so this may be normal during the decline of a cycle, not just this one. Also, when they say there may be no sunspots by 2015, this is an extrapolation. Since we do not know what has happened in previous cycles regarding this more accurate measurement of magnetic fields from sunspots, it may be unrealistic to assume that the trend will continue. Tomas Hood, NW7US, interviewed Dr Penn this week in his podcast. It's a very interesting interview with lots of details on his research. Regarding sunspots disappearing, check out the comments from Steven Hammer, K6SGH, on his Web page.
Here's an interesting comment from Jim Williams, K5NN, of Wichita, Kansas. Jim wrote, "As an old retired electrical engineer and a ham dating back to 1952, I'm wondering what the explanation for consistent long skip might be. I have been involved in an informal net on 75 meter SSB for close to 50 of those years before going to work-about 7AM central time. We never used to have consistent problems with long skip; now, most mornings short skip is 200 miles. As I have been active through several sun spot minimums, the extended periods of long skip around daylight was never such a problem. Lately, it has taken a kilowatt to be just above the noise on a 100 mile path, the path normally has been good, even at 100 W level. Is a good plausible explanation in existence for these conditions?"
This brings to mind an August 2007 e-mail from Jerry Reimer, KK5CA, of Spring, Texas. Jerry mentioned that short skip on low frequencies depends on Near Vertical Incidence Skywave (NVIS) propagation. The propagation out to 100 miles depends on the high angle component of the antenna radiation bouncing or refracting off the ionosphere overhead. Longer skip depends on lower angle radiation. Jerry mentioned that for reliable short skip propagation, the frequency used should be only 50-80 percent of the fMUF.
Recent fMUF values from ionosonde data may be found here. If I click on the Boulder (Colorado) data, I see that over the past day the fMUF above Colorado may not be high enough to support short skip on 75 meters. The HAP (Hourly Area Predictions) charts are another source of real time info. Select a location from the drop down menu and you see a map showing propagation for various frequencies from that location. For more information about ionosondes, check this link out.
We got a report this week from Luke Steele, VK3HJ, in Benloch, Victoria, Australia. He will soon see the spring equinox down under (our autumnal equinox in the Northern Hemisphere is September 23, nearly three weeks from now), and notes at the end of his comments that he echoes K5NN regarding 80 meters.
"Just thought I'd drop a line and offer a DX perspective from my modest station in central Victoria, 50 miles northwest of Melbourne. My main antenna here is a 520 foot doublet at 60 feet with open wire to the shack, and a 1/4 wave vertical for 40 meters. Conditions the past few months have been very quiet, with very little happening on 20 meters and up, although I have still been working DX on CW and PSK most evenings (0800-1400 UTC). There are nearly always Russians to be seen on 20 meter PSK afternoons and evenings here. Forty and 30m provide continuing interest, particularly CW and PSK. Contacts to the Pacific Islands and South Asia and Japan are available in the evenings when I get on the air. There are some Indian Ocean contacts to be had, recently with VQ9JC and VQ9LA on Diego Garcia on 20 and 40 meters, and 4S7NE in Sri Lanka. Seventy-five meter SSB looks average for this time of year, with USA on most evenings. Forty meter CW to USA is mostly good, and SSB is light. I've also been hearing some North America on 160 meter CW most evenings and I have worked a couple. Top band okay out to Western Australia, Queensland and the western Pacific Islands (out to about 2500 miles). There has been nothing much from Europe, Africa, South America and the Caribbean for some months. Local club nets on 80 meters in the evenings have sometimes been difficult over the past few months, with close stations weak and those beyond about 500 miles loud. There's also DX to be had in the mornings here, but I usually miss that, not being a 'morning person'! So, there is still DX to be had, but operating modes and methods need to change to suit."
Bob Karpinski, WB8B, from Clinton Township, Michigan, has been having fun running QRP on 17 meters. Bob wrote: "There was a very sporadic opening with very good signals from the far western edge of Europe on 17m from 2300-0000 UTC from Michigan. I worked Nelson Resende, CT1JOP, on 17 meter CW with only 1 W on August 27 at 2330 UTC! He lowered his power to 5 W during the QSO and we had a teo-way QRP contact with 559 signals."
Steve Ickes, WB3HUZ, of Lightfoot, Virginia wrote: "Despite the lack of sunspots, I've been enjoying worldwide DX on 40 meters daily. Eighty meters has been more active in the last few weeks, with very strong signals (5-9+20) from many stations out of Europe. It can only get better as the static begins to subside with fall coming."
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.