SB PROP @ ARL $ARLP015<br />ARLP015 Propagation de K7RA<br /><br />ZCZC AP15<br />QST de W1AW <br />Propagation Forecast Bulletin 15 ARLP015<br />>From Tad Cook, K7RA<br />Seattle, WA April 11, 2003<br />To all radio amateurs <br /><br />SB PROP ARL ARLP015<br />ARLP015 Propagation de K7RA<br /><br />Sunspots and solar flux values dropped this week after a rise the<br />week prior. Average daily sunspot numbers were down nearly 72<br />points, while average daily solar flux values were down nearly 21<br />points. Solar flux is expected to decline, dropping below 100 by<br />Sunday, April 13. It should reach a minimum around 85 from April<br />16-17.<br /><br />A solar flux value of 85 is about equivalent to a nominal sunspot<br />number of 28.7. Solar flux at 70 or below is generally what you see<br />when the sunspot count is 0. For instance, for over a month from<br />September 13 to October 20, 1996 the sunspot number was 0 every day.<br />Solar flux during this period ranged from 66.4 to 70. On Monday of<br />this week helioseismic holography revealed a large sunspot group<br />forming on the sun's far side.<br /><br />This was another week with active geomagnetic conditions, although<br />the planetary A index never went above 26. April 8 brought a brief<br />G1 level geomagnetic storm caused by solar wind. On April 10 earth<br />is entering another solar wind stream. The predicted planetary A<br />index value for Friday is 20, followed by 15 for every day through<br />April 19.<br /><br />Pat, W5OZI in Texas wrote last week to say he'd been hearing his own<br />backscatter echoes from the south on 6-meters. He was working ZP6CW<br />in Paraguay with the ZP6 beaming west. On April 4 Pat wrote,<br />"Yesterday, was the same, highlighted by a QSO with 5W1SA in Western<br />Samoa at 2202z followed an hour later with a quick QSO with ZL3TY."<br /><br />Spaceweather.com is showing a neat drawing of twenty days of a<br />sunspot group's progression across the solar disk, from March 12<br />through March 31. See it at<br />
http://spaceweather.com/swpod2003/10apr03/blom.jpg.<br /><br />This web site is produced by Dr. Tony Williams, who has a new<br />service out called Space Weather Phone. This service provides verbal<br />alerts of space weather events, and you can set alert levels and<br />times of day when it will call you concerning geomagnetic storms and<br />aurora warnings. You can learn about it at<br />
http://www.spaceweatherphone.com.<br /><br />Here are some web sites we haven't mentioned in awhile. Check<br />
http://www.sec.noaa.gov/solar_images/index.html for an archive of<br />solar images. For daily space weather, check<br />
http://www.sec.noaa.gov/SWN/ and
http://spaceweather.com. For daily<br />space weather alerts, check<br />
http://www.sec.noaa.gov/alerts/solar_indices.html.<br /><br />For more information about 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.<br /><br />Sunspot numbers for April 3 through 9 were 154, 148, 94, 75, 77, 52,<br />and 88, with a mean of 98.3. 10.7 cm flux was 155.7, 165.5, 137.4,<br />125.9, 115.6, 112.3, and 109.4, with a mean of 131.7. Estimated<br />planetary A indices were 14, 26, 23, 9, 6, 20, and 25, with a mean<br />of 17.6.<br />NNNN<br />/EX
