SB PROP @ ARL $ARLP039<br />ARLP039 Propagation de K7VVV<br /><br />ZCZC AP39<br />QST de W1AW <br />Propagation Forecast Bulletin 39 ARLP039<br />>From Tad Cook, K7VVV<br />Seattle, WA September 20, 2002<br />To all radio amateurs <br /><br />SB PROP ARL ARLP039<br />ARLP039 Propagation de K7VVV<br /><br />Average sunspot numbers were up a bit this week compared to last,<br />and solar flux on average was about the same. Solar flux peaked in<br />the short term on September 10 at 220.5 and has been mostly<br />declining since. Solar flux on Tuesday through Thursday of this week<br />was 194, 176.8 and 165.3, and for Friday though Sunday is predicted<br />at 165, 160 and 155. Sunday's value may continue for a few more days<br />and should be the minimum for the near term. Assuming returning<br />activity from the current solar rotation, solar flux is expected to<br />peak again around October 6-11.<br /><br />The big news this week though is the autumnal equinox, set for early<br />this Monday UTC. 10-meters is seasonally best around this time, and<br />K7SS reports a great opening during the recent Worked All Europe<br />contest between the West Coast and Europe on 10-meters on Friday and<br />Saturday mornings. He is also hearing Africa via longpath on<br />15-meters at night, and 20-meters is staying open quite late toward<br />the west.<br /><br />Gary, N8MJZ asks why the equinox is good for DX. Around the equinox<br />the southern and northern hemispheres get approximately an equal<br />amount of sunlight. This means that there aren't any short days<br />anywhere on the planet with the accompanying early winter band<br />closings, and with more equal solar radiation around the earth MUFs<br />are generally higher.<br /><br />Go to<br />http://www.ucar.edu/communications/newsreleases/2002/space.html for<br />an article about a new space weather forecasting initiative funded<br />by the National Science Foundation. This article also references the<br />''Windows to the Universe'' site at http://www.windows.ucar.edu/,<br />which has a number of interesting features, including views of<br />electron densities in the ionosphere and details on ionospheric<br />sounding.<br /><br />Sunspot numbers for September 12 through 18 were 258, 246, 256, 168,<br />190, 228 and 225, with a mean of 224.4. 10.7 cm flux was 212.4,<br />206.1, 206.9, 187.8, 182.6, 194, and 176.8, with a mean of 195.2.<br />Estimated planetary A indices were 17, 16, 11, 8, 8, 13, and 14,<br />with a mean of 12.4.<br />NNNN<br />/EX