The K7RA Solar Update
SEATTLE, WA, Aug 13, 2004--Big sunspot 649 rotated back
into view this week, and sunspot and solar flux numbers are up. Average daily
sunspot number for the week August 5-11 rose more than 35 points (from the
previous week) to 77.9, and average daily solar flux was up more than 18 points
to 106.5. There were no large geomagnetic events--only some periods of
unsettled to active conditions.
Sunspot 649 is currently in the center of the visible
solar disk and pointed straight toward Earth. It is a possible source of solar flares over the next few days. Solar flux
is expected to rise over the weekend, peaking below 170 from August 15-17. The
Prague Geophysical Institute predicts unsettled geomagnetic conditions for
August 13, unsettled to active conditions for August 14, and quiet to unsettled
conditions for August 15-16.
A solar cycle prediction released from NOAA SESC this week
still shows the current cycle bottoming out around the end of 2006 and the
start of 2007. It shows the lowest sunspot numbers from December 2006 to
January 2007 and the lowest solar flux values from September 2006 through April
2007. For the start of the next cycle, the prediction goes out as far as
December 2007, with a predicted smoothed sunspot number of 21. That's around
the same value predicted for January-February 2005. So, with the cycle
declining, their guess is that sunspot activity shouldn't return to the level
of early 2005 until the end of 2007. This suggests that activity won't return
to current levels until some time in 2008, although it is important to remember
that activity in the rising part of the cycle increases more rapidly than it
declines on the down side of the cycle.
Thomas Giella, KN4LF, wrote to announce a new e-mail
listserver for propagation discussions. You can sign up on the Web, or
subscribe by sending an e-mail
with the word "subscribe" in the message body or subject line.
Reader David Moore sent in a link to an article about
research into the injection of solar wind plasma into Earth's magnetic field.
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 August 5 through 11 were 36, 52, 71,
77, 101, 93 and 115, with a mean of 77.9. The 10.7 cm flux was 88.9, 91, 94.6,
104.8, 113.9, 121.4 and 130.8, with a mean of 106.5. Estimated planetary A
indices were 7, 7, 20, 5, 13, 14 and 13, with a mean of 11.3. Estimated
mid-latitude A indices were 5, 3, 11, 2, 12, 12 and 10, with a mean of 7.9.
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: 10:38 AM, 13 Aug 2004 ET
Page author: awextra@arrl.org
Copyright © 2004, American Radio Relay League, Inc. All Rights Reserved.
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