The K7RA Solar Update
SEATTLE, WA, Sep 10, 2004--Sunspot numbers and solar flux rose during the past week. The average of the daily sunspot number for the reporting period compared to the previous seven days rose nearly by 30 points to 57. Average daily solar flux was up more than 16 points to 106.1. Solar flux is predicted to rise over the next few days. Predicted solar flux is 135 for September 10 and it's expected to remain around 140 for the next four days or so. Fortunately, the planetary A index is expected to remain low, with predicted values September 10-13 at 5, 8, 8 and 10.
Bill Burrows, WA7NCL, wrote to say he likes to use the K index as an indicator of whether conditions will be good. The current mid-latitude K index is available via WWV, and it's updated every three hours. The K index is broadcast at 18 minutes past each hour on WWV and at 45 minutes after the hour on WWVH. It's available anytime by telephone (303-497-3235) or via the Web on the NOAA Space Environment Center (SEC) site. (The mid-latitude K index at 0600 UTC on September 10 was zero. It doesn't get any quieter than that.)
WA7NCL sent along a great resource for predictions of the K index also from the NOAA SEC site. There are several text links on the left for the predictions and also some graphs for comparing recent predictions with actual conditions. The prediction itself is on the text link called "Output List." Ideally, we would like to see a low K index along with higher sunspot and solar flux values.
This weekend is the Worked All Europe DX Contest (SSB). Conditions should be good. And don't forget the autumnal equinox in less than two weeks. As we approach fall, HF propagation will be getting seasonally better.
For more information concerning propagation and an explanation of the numbers used in this bulletin see the ARRL Technical Information Service Propagation page.
Sunspot numbers for September 2 through 8 were 25, 25, 28, 59, 82, 95 and 85, with a mean of 57. The 10.7 cm flux was 93.9, 96.7, 99.3, 103.2, 106.5, 118.9 and 124.5, with a mean of 106.1. Estimated planetary A indices were 9, 3, 4, 7, 14, 16 and 9, with a mean of 8.9. Estimated mid-latitude A indices were 8, 1, 2, 5, 9, 11 and 4, with a mean of 5.7.
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 Frida,y and an abbreviated version also appears in The ARRL Letter. Readers may contact the author via e-mail.
Page last modified: 12:18 PM, 10 Sep 2004 ET
Page author: awextra@arrl.org
Copyright © 2004, American Radio Relay League, Inc. All Rights Reserved.
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