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The
K7RA Solar Update
SEATTLE, WA, Dec 29, 2003--This is the last
propagation bulletin for 2003. It includes the sunspot and solar flux numbers
for the normal reporting week which were not included in the update released
prior to the holiday period.
During the reporting week of December 18-24,
average solar flux and sunspot numbers were quite a bit higher than the
previous seven-day period. Geomagnetic indices showed more stable conditions,
with the average planetary A index about half the previous average. Geomagnetic
indices have remained stable since December 24, and sunspot numbers have been
declining along with the solar flux.
Geomagnetic conditions should remain stable
until New Year's Eve, Wednesday, December 31, when recurring solar activity is
expected to manifest as a rise in A indices. The predicted planetary A index
for December 29 to January 11 is 10, 10, 15, 30, 20, 15, 15, 30, 35, 35, 35,
35, 20 and 15. Solar flux is expected to decline over the next few days,
dipping below 100 after January 1 and for the following 10 days or so.
Henry Platt, W3UI, commented on the quiet
geomagnetic conditions on December 24-25. With K indices at 1 or 2, from his
home in Bryn Mawr, Pennsylvania, using 100 W and a half-sized dipole on 80
meters, he was able to work nearly every European station heard on his first
attempt. He contrasts this to rough conditions over the past year on the same
band with the same gear. The key seems to be long winter nights with quiet
geomagnetic conditions.
ARRL Straight Key Night is a popular
operating activity beginning New Year's Eve, December 31, in the US (0000 UTC)
and continuing for the next 24 hours to 2400 UTC on January 1. This is a fun
and relaxed event. Your bulletin author plans to participate if he can only
find his old J-38. Full information is available on the ARRL Web site.
For more information about propagation and an
explanation of the numbers used in this bulletin see the Propagation page on the ARRL Web site.
Sunspot numbers for December 18 through 24
were 114, 113, 104, 105, 152, 144 and 100, with a mean of 118.9. The 10.7 cm
flux was 123, 122.5, 130.1, 133.4, 137.6, 142 and 138.9, with a mean of 132.5.
Estimated planetary A indices were 8, 7, 16, 21, 15, 9 and 8, with a mean of
12.
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 via k7ra@arrl.net.
Page last modified: 10:27 AM, 29 Dec 2003 ET
Page author: awextra@arrl.org
Copyright © 2003, American Radio Relay League, Inc. All Rights Reserved.
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