The K7RA Solar Update
SEATTLE,
WA, Apr 15, 2005--This week saw an insignificant rise in
average daily sunspot numbers and solar flux compared to the previous
week. Average daily sunspot numbers were up by a little more 1 point
to 40.6. Average daily solar flux rose by more than 5 points to 86.9.
There was a rise in geomagnetic
activity due to a solar wind stream from a coronal hole. The
planetary A index numbers for April 12, 13 and 14 were 30, 26 and 19.
We have moved out of the solar wind, and the prediction is for
quieter conditions. The predicted planetary A index for April 15, 16,
17 and 18 is 12, 10, 8 and 5. Sunspot counts and daily solar flux
numbers are expected to stay about the same--perhaps declining
slightly after April 19.
On the Web site for the Western
Washington DX Club I spotted a number of links to
presentations from past club meetings, either on technical topics or
DXpeditions. One that might be of interest to “Solar Update”
readers is a PDF of K9LA’s talk on 160 meter propagation at
last summer’s Northwest DX Convention. This very interesting
tutorial covers several aspects of 160-meter propagation, and it
examines the notion that this band is better during the sunspot
minimum.
For
more information concerning radio propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service
Propagation page.
Sunspot numbers for April 7
through 13 were 49, 56, 43, 42, 17, 32 and 45, with a mean of 40.6.
The 10.7 cm flux was 87.8, 87.7, 88.4, 88.3, 87.5, 84.9 and 83.5,
with a mean of 86.9. Estimated planetary A indices were 8, 4, 4, 4,
10, 30 and 26, with a mean of 12.3. Estimated mid-latitude A indices
were 4, 2, 2, 2, 6, 23 and 18, with a mean of 8.1.
- 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 appears in The
ARRL Letter. Readers may contact the author via
e-mail.
-
Page last modified: 10:54 AM, 15 Apr 2005 ET
Page author: awextra@arrl.org
Copyright © 2005, American Radio Relay League, Inc. All Rights Reserved.
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