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ARRL Propagation Bulletin ARLP011 (2001)

ARLP011 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 11  ARLP011
From Tad Cook, K7VVV
Seattle, WA  March 16, 2001
To all radio amateurs 

ARLP011 Propagation de K7VVV

Solar flux declined this week, having reached a short-term peak a
week prior to Wednesday. But average daily solar flux and sunspot
numbers were higher this week than last. Daily sunspot numbers
reached a peak of 174 on Monday. This is the highest it has been
since February 9, when it was 179, or January 23, when it was 178.

Geomagnetic conditions have been quiet, with A indices in the
single-digits. Quiet conditions should continue, although there is a
possibility that sunspot group 9373, currently at the center of the
solar disk oriented toward earth, could produce some solar flares on
Thursday or Friday. You'll hear the results on the WWV reports a few
days later if the K index rises above 3.

Solar flux is expected to be around 135 on Friday and 130 for the
following few days, then rise to around 145 on March 22-24. By
comparison, a year ago the average sunspot number and solar flux
reported in this bulletin (ARLP011) was respectively 193.4 and

Scott Craig has a revised version of his Solar Data Plotting
Utility, which works with the data presented in this bulletin. The
new version was released last week, and has a new feature which can
connect to the internet and automatically download the solar data
from an ARRL FTP site. His website is at, and the software is at

Next week is the spring equinox, with anticipated spring propagation
conditions. 15 and 20 meters should be open later into the evening,
with 20 meters possibly open all night. 10 meters should improve
around the change of seasons, but will probably degrade for
worldwide propagation as spring moves toward summer.

Sunspot numbers for March 8 through 14 were 98, 113, 131, 139, 174,
110 and 159 with a mean of 132. 10.7 cm flux was 167.2, 161.4,
160.1, 157.8, 157.6, 147.3 and 142.2, with a mean of 156.2, and
estimated planetary A indices were 6, 6, 5, 4, 10, 7 and 7 with a
mean of 6.4.


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