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The K7VVV Solar Update
SEATTLE, WA, Jan 4, 2002--Solar activity has been lower over
the past week. Average daily sunspot numbers during the week of January 3-9
were nearly 52 points less than the previous week, and average daily solar flux
dropped by 42 points. Along with fewer sunspots there was very little
geomagnetic activity--which is great for HF propagation because of lower
absorption. Many periods over the past week had planetary and mid-latitude K
indices of zero or one.
Solar
flux probably reached a short-term minimum when it was 188.6 on Monday.
Predicted solar flux for Friday through Monday is 230, 235, 240 and 245. Solar
flux should peak near 260 around next Thursday or Friday, then reach another
short-term minimum during the first week of February.
Did
we say this week was quiet? This won't last. A high-speed stream of energy from
a coronal hole is due, and the predicted planetary A index indicates a
geomagnetic storm. Values for Friday through Sunday should be around 30, 20 and
15. There was also a large solar flare at 1801 UTC on Wednesday. Although it
came from a sunspot near the center of the visible solar disk, the blast of
energy from this flare should not bother Earth.
AD4JE
wrote to suggest a good introduction to HF propagation on the Web. He
also asked about Web sites for solar flux, A and K indices, and I referred him
to this flux density data Web site, as well as
the Daily Solar Data gopher site and the Daily Geomagnetic Data gopher site. KC7GOL also
wrote to suggest NASA's Space Weather site.
Several
readers wrote to ask about a problem using the WA4TTK graphing software with
last week's bulletin. This software can grab the data from the bulletin
automatically, but last week the use of a phrase in the text of the bulletin
which was similar to one at the end in the data area caused a parsing error.
WA4TTK has an explanation for these problems and their solutions on his
"CraigCentral" Web site.
You can download his software from his Web site. With recent versions
of the solar plotting software, you can use the ftp function and grab data from
the ARRL to update the data file, instead of entering it by hand or having the
software grab the data from your copy of the bulletin.
Sunspot
numbers for January 3 through 9 were 229, 248, 201, 143, 158, 143 and 159, with
a mean of 183. The 10.7-cm flux was 220.3, 218.2, 212.2, 196.6, 188.6, 199.2
and 228.5, with a mean of 209.1. Estimated planetary A indices were 3, 3, 3, 4,
7, 7 and 3, with a mean of 4.3.
Amateur
solar observer Tad Cook, K7VVV 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 via k7vvv@arrl.net.
Page last modified: 10:33 AM, 11 Jan 2002 ET
Page author: awextra@arrl.org
Copyright © 2002, American Radio Relay League, Inc. All Rights Reserved.
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