The K7RA Solar Update
SEATTLE, WA, Apr 8, 2004--This bulletin is going out a day
early because ARRL Headquarters is closed Friday, April 9. Solar flux values
and sunspot numbers both dropped this week. Average daily sunspot numbers
declined more than 46 points, and solar flux was down nearly 20.
Solar flux is expected to rise over the next couple of
days. Predicted solar flux for Thursday through Monday, April 8-12, is 105 for
Thursday and Friday and 100 for Saturday through Monday. Flux values and
sunspots should rise again for a few days next week.
A coronal mass ejection near Sunspot 588 spewed toward Earth
April 6. Currently that sunspot is squarely in the center of the solar disk,
aimed straight at us. The ejection should hit Earth today, April 8. The predicted
planetary A index for Thursday through Monday, April 8-12, is 30, 20, 15, 12
and 8.
There was a solar wind a couple of days back that caused
geomagnetic instability late on April 5 and through most of April 6. Another
solar wind on April 3 caused similar conditions.
For more information concerning propagation and an
explanation of the numbers used in this bulletin see the Propagation page on the ARRL Web site.
Sunspot numbers for April 1 through 7 were 100, 99, 68,
69, 85, 66 and 57, with a mean of 77.7. The 10.7 cm flux was 112.8, 108.1,
107.4, 108.9, 108.7, 101.4 and 98.1, with a mean of 106.5. Estimated planetary
A indices were 3, 3, 23, 12, 14, 21 and 10, with a mean of 12.3.
Amateur
solar observer Tad Cook, K7RA, Seattle, Washington, provides this weekly report
on solar conditions and propagation. This report also is available via W1AW
every Friday and an abbreviated version also appears in The ARRL Letter. Readers may contact the author k7ra@arrl.net.
Page last modified: 10:28 AM, 08 Apr 2004 ET
Page author: awextra@arrl.org
Copyright © 2004, American Radio Relay League, Inc. All Rights Reserved.
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