SB PROP @ ARL $ARLP001<br />ARLP001 Propagation de K7RA<br /><br />ZCZC AP01<br />QST de W1AW <br />Propagation Forecast Bulletin 1 ARLP001<br />>From Tad Cook, K7RA<br />Seattle, WA January 6, 2006<br />To all radio amateurs <br /><br />SB PROP ARL ARLP001<br />ARLP001 Propagation de K7RA<br /><br />Average daily sunspot numbers for the past week (December 29 through<br />January 4) were nearly 22 points below the previous period. Average<br />daily solar flux was about the same. Average daily mid-latitude<br />geomagnetic indices (A and K index) were exactly the same, and the<br />planetary A and K index were slightly lower.<br /><br />For the near term expect sunspot numbers and solar flux to stay<br />around the same levels (low), but gradually rise to a short term<br />peak around January 15-16. The A and K index should also stay quiet,<br />with a returning active patch of Sun causing unsettled to active<br />geomagnetic conditions around January 16 and again around January<br />23-24. January 10-12 should have very quiet, stable geomagnetic<br />indicators.<br /><br />Those forecasts are from the U.S. Air Force, via NOAA. Geophysical<br />Institute Prague expects quiet conditions for January 9-11, quiet to<br />unsettled today, January 6, and again on January 12, and unsettled<br />conditions January 7-8. Currently our Sun is quiet, and the<br />interplanetary magnetic field points north, both indicators of quiet<br />geomagnetic conditions.<br /><br />Now that we have the solar flux and sunspot numbers for all of 2005,<br />it is time for a review of annual averages.<br /><br />Average daily sunspot numbers for the years 1999 through 2005 were<br />136.3, 173, 170.3, 176.6, 109.2, 68.6 and 48.9. Average daily solar<br />flux for the same years was 153.7, 179.6, 181.6, 179.5, 129.2, 106.6<br />and 91.9. The steady decline over each calendar year since the<br />2000-2002 period should continue through the end of this year. Two<br />years from now we should know when trends turned around.<br /><br />David Greer, N4KZ of Frankfort, Kentucky reports more surprising<br />short lived 10 meter propagation in the form of an opening toward<br />Europe on December 31. Last Saturday morning he heard many strong<br />European stations on 12 and 15 meters, so he went to 10 meters and<br />called CQ at 1427z with his 3-element Yagi pointed toward Europe.<br />I5KAP answered with a weak but readable signal. Dave reports, "Seven<br />minutes later I heard F5LIW calling CQ and worked him too. Again,<br />signals were weak but readable. After we signed, he began calling CQ<br />again but with no takers from what I could hear. At 1439z, I heard<br />IK4GRO calling CQ. At S7, he had the strongest signal. We exchanged<br />reports and he began calling CQ again but no takers from what I<br />could hear. Then the signals were gone." Dave runs 100 watts on 10<br />meters.<br /><br />Felipe Ceglia, PY1NB of the state of Rio de Janeiro in Brazil passes<br />word that he has a web site for DXers, which can be found at,<br />
http://www.dxwatch.com/. He carries this bulletin, along with<br />spotting services.<br /><br />Carl Luetzelschwab, K9LA sent in an interesting piece that he wrote<br />for this week's bulletin in response to an email exchange with Red<br />Haines, WO0W. It is titled "The T Index and SSNe."<br /><br />Carl writes, "Due to the day-to-day variability of the ionosphere,<br />our propagation prediction programs use a monthly median model of<br />the ionosphere. Thus the prediction outputs (usually MUF and signal<br />strength) are statistical over a month's time frame. We have a<br />monthly median model, as opposed to a daily model, because the<br />developers did not find a satisfactory correlation between what the<br />Sun was doing on a given day and what the ionosphere was doing on<br />the same day. The proper correlation was between smoothed sunspot<br />number (or smoothed solar flux) and monthly median ionospheric<br />parameters (foE, foF2, hmF2, etc)."<br /><br />He continues, "In order to get a better picture of what the<br />ionosphere is doing 'now', two similar methods have been developed:<br />the T Index and SSNe. The T Index comes out of Australia's IPS<br />(Ionospheric Prediction Service), and is named after its developer<br />Jack Turner. SSNe (equivalent sunspot number) was developed by the<br />US Air Force Global Weather Central organization, and is available<br />from Northwest Research Associates. The websites are,<br />
http://www.ips.gov.au/HF_Systems/4/2 and,<br />
http://www.nwra-az.com/spawx/ssne24.html, respectively."<br /><br />Carl goes on to say, "Both of these methods basically vary the<br />sunspot number in a F2 region model of the ionosphere to force the<br />model to a best fit to current foF2 data from worldwide ionosondes.<br />Note the phrase 'best fit' - it's not a perfect fit, as the<br />ionosphere does not necessarily track at all locations. For example,<br />the F2 region ionization over the Millstone Hill (MA) ionosonde may<br />increase at a given hour, while just 400 miles away the F2 region<br />ionization over the Wallops Island (VA) ionosonde may decrease at<br />the same time."<br /><br />He ends by saying, "What does using the T Index and SSNe buy us?<br />Neither gives us a daily model of the ionosphere due to the issue<br />cited in the previous paragraph. Nor does either take into account D<br />region and E region issues. But with respect to the F2 region, they<br />close the gap between the heavily averaged smoothed sunspot number<br />and short-term increases or decreases in sunspot activity (they also<br />can show the effect of geomagnetic storms). An example of this is<br />late December 2005. The official smoothed sunspot number for<br />December 2005 will come in somewhere between 10 and 20, but the<br />increased sunspot activity at the end of the year indicated that<br />using a sunspot number of 40 in your favorite prediction program<br />(from the SSNe website) would have given you a better 'now'<br />prediction."<br /><br />Thank you, Carl!<br /><br />If you would like to make a comment or have a tip for our readers,<br />email the author at, k7ra@arrl.net.<br /><br />For more information concerning radio propagation and an explanation<br />of the numbers used in this bulletin see the ARRL Technical<br />Information Service propagation page at,<br />
http://www.arrl.org/tis/info/propagation.html. An archive of past<br />propagation bulletins is found at,
http://www.arrl.org/w1aw/prop/.<br /><br />Sunspot numbers for December 29 through January 4 were 77, 67, 62,<br />41, 37, 39 and 25 with a mean of 49.7. 10.7 cm flux was 90.3, 89.9,<br />87.4, 87.4, 84.5, 84.9, and 84, with a mean of 86.9. Estimated<br />planetary A indices were 8, 7, 9, 4, 5, 3 and 2 with a mean of 5.4.<br />Estimated mid-latitude A indices were 7, 6, 9, 5, 5, 3 and 1, with a<br />mean of 5.1.<br />NNNN<br />/EX
