De: "ARRL Web site" À: Cc: Objet: ARLP036 Propagation de K7RA Date: vendredi 4 septembre 2009 18:17 SB PROP @ ARL $ARLP036 ARLP036 Propagation de K7RA ZCZC AP36 QST de W1AW Propagation Forecast Bulletin 36 ARLP036 From Tad Cook, K7RA Seattle, WA September 4, 2009 To all radio amateurs SB PROP ARL ARLP036 ARLP036 Propagation de K7RA 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. The monthly average of the daily sunspot number, January through 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 through 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 through 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 through August. The previous figure, for June, is an average of daily sunspot numbers for May through July. In other words, sum all the daily sunspot numbers from May 1 through July 31, which equals 478. Divide by 92, which is 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 at, http://science.nasa.gov/headlines/y2009/03sep_sunspots.htm 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 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. NW7US interviewed Dr. Penn this week in his podcast, which you can download from http://tinyurl.com/NSWARPP-E04. Very interesting interview with lots of details on his research. Regarding sunspots disappearing, check out the comments from K6SGH on his web page, http://www.k6sgh.com/index.html. An interesting comment came 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 (2 uncles and others, lots of silent keys now) 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 sunspot 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 hundred mile path, the path normally has been good, even at 100 watt level. Is a good plausible explanation in existence for these conditions?" This brings to mind an August 2007 email from Jerry Reimer, KK5CA of Spring, Texas. Jerry mentioned that short skip on low frequencies depends on NVIS (Near Vertical Incidence Skywave) 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 at http://www.swpc.noaa.gov/ftpmenu/lists/iono_day.html. 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. Another source of real time info are the HAP (Hourly Area Predictions) charts at http://www.ips.gov.au/HF_Systems/6/6/1. Select a location from the drop down menu, and you see a map showing propagation for various frequencies from that location. Go to http://www.ngdc.noaa.gov/stp/IONO/ for more information about ionosondes. 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 note 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 NW 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 40m." "Conditions the past few months have been very quiet, with very little happening on 20m and up, although I have still been working DX on CW and PSK most evenings (0800-1400z). There are nearly always Russians to be seen on 20m PSK afternoons and evenings here." "40 and 30m provide continuing interest, particularly CW and PSK. Contacts to the Pacific Islands and S Asia and JA are available in the evenings when I get on the air. Some Indian Ocean contacts to be had, recently with VQ9JC and VQ9LA on Diego Garcia on 20 and 40m, and 4S7NE in Sri Lanka." "75m SSB looks average for this time of year with USA on most evenings. 40m CW to USA is mostly good, and SSB is light. I've also been hearing some North America on 160m CW most evenings, and have worked a couple. Top band OK out to Western Australia, Queensland and the western Pacific Islands (out to about 2500mi)." "Nothing much from Europe, Africa, South America and the Caribbean for some months." "Local club nets on 80m in the evenings have sometimes been difficult, over the past few months with close stations weak, those beyond about 500mi 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." Thanks, Luke! 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 EU on 17m from 2300-0000z from Michigan. CT1JOP was worked on 17m CW with only 1 watt on 8/27/09 2330z! He lowered his power to 5w during the QSO and we had a 2-way QRP contact with 559 signals." Steve Ickes, WB3HUZ of Lightfoot, Virginia wrote: "Despite the lack of sunspots, I've been enjoying world wide DX on 40 meters daily. 80 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." If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net. For more information concerning radio propagation, see the ARRL Technical Information Service web page at, http://www.arrl.org/tis/info/propagation.html. For a detailed explanation of the numbers used in this bulletin, see http://www.arrl.org/tis/info/k9la-prop.html. An archive of past propagation bulletins is at http://www.arrl.org/w1aw/prop/. Monthly propagation charts between four USA regions and twelve overseas locations are at http://www.arrl.org/qst/propcharts/. Instructions for starting or ending email distribution of this bulletin are at http://www.arrl.org/w1aw.html#email. Sunspot numbers for August 27 through September 2 were 0, 0, 0, 0, 12, 12, and 0 with a mean of 3.4. 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. Estimated planetary A indices were 5, 2, 2, 19, 5, 4 and 3 with a mean of 5.7. Estimated mid-latitude A indices were 4, 2, 2, 12, 5, 2 and 2 with a mean of 4.1. NNNN /EX