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ARRL Propagation Bulletin ARLP001 (1997)

ARLP001 Propagation de KT7H

Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, KT7H
Seattle, WA  January 3, 1997
To all radio amateurs

ARLP001 Propagation de KT7H

Solar activity was down over the past couple of weeks, as we settle
back into conditions consistent with the bottom of the solar cycle
after the recent, probably final upsurge in activity from the dying
cycle 22.

Looking at the long term, recent data shows that sunspot numbers
probably bottomed out around June or July of last year, but should
return to late 1994 levels around June of this year.  By August
some projections show sunspot numbers about three times what they
were during the same month a year earlier, and by December about
four times the average for December, 1996.

For the ARRL RTTY Roundup this weekend look for slightly rising
solar flux to the mid-seventies, with a possible small bump in
geomagnetic activity coming Monday.  Based on the 27 day solar
rotation, the flux is expected to rise to around the mid-eighties
by January 14, then drop below 80 a few days later, bottoming out
in the low seventies from January 17 through the end of the month.

Recently 15 meters has seen some improvement, although a lot of the
observed propagation is north-south, also referred to as trans-
equatorial.  Look for openings on 17 through 10 meters during
daylight hours, and good conditions on 20 meters.  Look for
conditions to be best on 20 after sunrise and again before sunset.
40 meters is still a good bet for long and medium distance
propagation, and given the continued low solar activity, look for
openings on 80 and 160 meters during the long hours of darkness.

Recently we have been unable to get solar flux numbers resolved to
a tenth of a point.  This should change soon.

Sunspot Numbers for December 19 through 25 were 23, 13, 28, 26, 24,
0 and 0, with a mean of 16.3.  10.7 cm flux was 87.4, 83, 83.7,
81.5, 79.5, 79 and 77, with a mean of 81.6.  Planetary A indices
for the same period were 2, 2, 4, 6, 10, 3, and 6, with a mean of

Sunspot Numbers for December 26 through January 1  were 0 every
day, which is a mean of 0.  10.7 cm flux was 76, 75, 74, 74, 73, 72
and 72, with a mean of 73.7.  Planetary A indices for the same
period were 3, 1, 4, 3, 8, 4, and 2, with a mean of 3.6.


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