SB PROP @ ARL $ARLP020<br />ARLP020 Propagation de K7RA<br /><br />ZCZC AP20<br />QST de W1AW <br />Propagation Forecast Bulletin 20 ARLP020<br />>From Tad Cook, K7RA<br />Seattle, WA May 16, 2003<br />To all radio amateurs <br /><br />SB PROP ARL ARLP020<br />ARLP020 Propagation de K7RA<br /><br />Disturbed conditions triggered by a continuous solar wind stream<br />appear to go on and on, week after week, seemingly without end.<br />Nice quiet conditions would result from a daily A index of 10 or<br />lower. Average daily conditions near that level haven't been<br />reported since the week of February 20-26 when the daily average A<br />index was 11.1, or January 9-15 when it was 9.1.<br /><br />Conventional wisdom says that disturbed conditions occur more often<br />when the solar cycle has passed the peak and is headed down, and<br />recent experience seems to bear this out. Recent forecasts for daily<br />solar flux and planetary A index don't predict a daily A index below<br />10 until May 31.<br /><br />A plot from Jim Secan and Northwest Research Associates shows the<br />decline of the solar cycle over the past year at<br />
http://www.nwra-az.com/spawx/ssne-year.html. The latest projection<br />has solar flux rising over the next few days to 110 on Saturday, May<br />17, 120 on Sunday and 125 on Monday. The daily planetary A index<br />projection shows an unsettled 15 thought the weekend, rising to 20<br />on Monday.<br /><br />The solar flux and sunspot numbers were lower this week than last,<br />but the A index was higher. The average daily sunspot number dropped<br />around 100 points from 146 to 46.4, and daily solar flux was down<br />over 40 points to 95.5. Average daily A index rose from 20.7 to<br />29.3.<br /><br />Last week we mentioned Scott Craig, WA4TTK and his solar plotting<br />utility freeware available at<br />
http://www.craigcentral.com/mystuff.asp. Scott says he usually gets<br />100-150 visits per day to his web page, but last Friday when the<br />bulletin came out he got 270, and Saturday it was 393.<br /><br />The announcement this week about the new 60-meter band brings<br />speculation about propagation characteristics. Initially this will<br />probably be used just for domestic communications, since no other<br />country has adopted these frequencies for the amateur service. A<br />quick look with a propagation prediction program shows the band<br />opening and closing at hours somewhere between the 75 and 40-meter<br />bands.<br /><br />With W6ELprop looking from Seattle to Atlanta, assuming that the<br />band is legal one month from now and the sunspot number is around<br />100, 60-meters seems to open a half hour earlier than 75- meters and<br />close a half hour later. Signal strengths during the peak hours,<br />which for the above parameters are from 0500-1000z, are between the<br />levels for 40 and 75-meters as well. A similar projection for<br />mid-September from California to Ohio shows similar characteristics,<br />although with more hours of darkness the openings are longer.<br /><br />Mark Roberts, KD5SMF sent an email this week asking for a source for<br />the numbers used in the W6ELprop software, a free windows-based<br />program that can be downloaded at
http://www.qsl.net/w6elprop/. I<br />wrote to him and said that it is probably better to take an average<br />of several days sunspot numbers and use that instead of the latest<br />daily solar flux. You can get both values at<br />
http://sec.noaa.gov/ftpdir/latest/DSD.txt, and several daily K<br />indices from
http://sec.noaa.gov/ftpdir/latest/DGD.txt.<br /><br />The latest mid-latitude K index is on WWV at 18 minutes after each<br />hour, or you can get the WWV message on the telephone at<br />303-497-3235. The text of that hourly message is available on the<br />web at
http://sec.noaa.gov/ftpdir/latest/wwv.txt.<br /><br />For more information on propagation and an explanation of the<br />numbers used in this bulletin see the Propagation page on the ARRL<br />Web site at
http://www.arrl.org/tis/info/propagation.html. You can<br />write to the author of this bulletin at k7ra@arrl.net.<br /><br />Sunspot numbers for May 8 through 14 were 33, 23, 22, 47, 66, 59,<br />and 75, with a mean of 46.4. 10.7 cm flux was 100.9, 97.1, 92.7,<br />91.5, 93.9, 96.1, and 96.3 with a mean of 95.5. Estimated planetary<br />A indices were 30, 29, 43, 31, 18, 27, and 27, with a mean of 29.3.<br />NNNN<br />/EX
