SB PROP @ ARL $ARLP051<br />ARLP051 Propagation de K7VVV<br /><br />ZCZC AP51<br />QST de W1AW <br />Propagation Forecast Bulletin 51 ARLP051<br />>From Tad Cook, K7VVV<br />Seattle, WA December 6, 2002<br />To all radio amateurs <br /><br />SB PROP ARL ARLP051<br />ARLP051 Propagation de K7VVV<br /><br />Average sunspot numbers were up a bit this week, and average daily<br />solar flux barely changed. Geomagnetic indices were quieter.<br /><br />Now that December is here, let's review average daily solar flux and<br />sunspot numbers for November, and compare them with previous months.<br />Here are monthly averages for solar flux and sunspot numbers for<br />this year. From January through November, 2002 the average daily<br />sunspot number for each month was 189, 194.5, 154.3, 144.4, 146,<br />183.5, 191, 206.4, 153.9 and 159.8. Average daily solar flux for the<br />same months was 227.3, 205, 179.2, 141.4, 148.7, 174.4, 183.9,<br />175.8, 167 and 168.7.<br /><br />This weekend is the ARRL 160-Meter Contest. It would be good to have<br />low geomagnetic activity for this contest. Right now the predicted<br />planetary A index for Friday through Monday is 12, 15, 20 and 15.<br />This indicates unsettled to active conditions on Saturday and Sunday<br />due to coronal hole effects. There is a chance of moderate solar<br />flare activity over the next few days. Solar activity is likely to<br />be low. Predicted solar flux for the next few days is 160-175.<br /><br />Chester, KD5TFK wrote in to ask, "How much longer can we expect<br />great propagation on 10-meters?" He assumes we are on the downside<br />of the current solar cycle.<br /><br />One way to look at this is to compare likely conditions for the<br />10-meter contest coming up the weekend of December 14-15. Last year<br />the average daily solar flux around the time of the contest was<br />about 228. This year it is likely to be about 175. If we check the<br />weekly Preliminary Report and Forecast of Solar Geophysical Data<br />from the NOAA SEC web site at<br />
http://www.sec.noaa.gov/weekly/index.html, they run an occasional<br />prediction for smoothed sunspot and solar flux numbers. The last<br />prediction was at the end of the November 5 issue. The smoothed flux<br />value they are predicting for December 2003 is about 41 points lower<br />than for December 2002, so let us use a value of 134 for December of<br />next year. Next try plugging these dates and values into W6ELprop<br />(see the site,
http://www.qsl.net/w6elprop/ ).<br /><br />If I do a 10-meter prediction for last December from Seattle to<br />Japan using a flux value of 228, I show a good predicted opening<br />from 2230-0130z with a relative dB level of 21. Run the same test<br />with a solar flux of 175, and the period shortens to 2230-0030z. Do<br />it again with 134 for the solar flux, and it shows a possibility of<br />an opening around 2300z.<br /><br />Try it again on 10-meters from Dallas to Brazil. Last year has a<br />strong opening from 1300-0030z, this year 1330-2330z, and next year<br />1400-2200z. The solar activity will gradually decrease, and<br />10-meters will be affected.<br /><br />Sunspot numbers for November 28 through December 4 were 124, 107,<br />150, 97, 155, 135, and 144, with a mean of 130.3. 10.7 cm flux was<br />139.7, 141.3, 146.2, 149.6, 146.1, 145.9, and 148.7, with a mean of<br />145.4. Estimated planetary A indices were 15, 14, 16, 16, 11, 11,<br />and 12, with a mean of 13.6.<br />NNNN<br />/EX
