SB PROP @ ARRL $ARLP039
ARLP039 Propagation DE KT7H
QST DE W1AW
Propagation Forecast Bulletin 39  ARLP039
>From Tad Cook, KT7H
Seattle, WA  September 23, 1994
To All Radio Amateurs
 
The Sun is quiet.  On Tuesday and Wednesday there were no visible
spots on the solar surface, and geomagnetic indices have been very
low as well.  The low geomagnetic indices (the K index and the
A index) mean stable conditions, but the lack of sunspots and
resulting low solar flux make the Maximum Usable Frequency on HF
paths low also.  This is not what we want to see as we enter the
Fall DX season, but be prepared for more of this over the next
several years.  As the current solar cycle declines, we can look
forward to the end of 1997 as the period in the next cycle when
solar activity will increase again to where it is now.  In the
interim, 1996 should be the year of the quiet Sun, with the lowest
average solar flux now projected for October of that year.  The
current projection based on the SESC Regression Model is for the
peak solar flux to be around August, 2000.
 
During the projected peak year of the next cycle, cycle 23, the
author of this bulletin will turn 48.  Starting out in amateur radio
at age 12 between cycles 19 and 20 gave an early start to observing
solar cycles, but still, one does not get to experience very many in
one lifetime.  It is also a sobering thought to realize that one
never knows when an extended period of quiet Sun, or no solar
activity for decades, might return.  There is evidence of several
periods like this throughout history, although none since the
invention of radio.  What other course might the development of
radio have taken if there were no sunspots for the first half of
this century?
 
Sunspot Numbers for September 15 through 21 were 11, 12, 19, 30, 29,
0 and 0, with a mean of 14.4.  10.7 cm flux was 71.5, 70.8, 70.3,
71.9, 70.2, 69.8 and 69.9, with a mean of 70.6.
 
Look for the solar flux to rise to around 90 at the first of
October, and then fall to the present level after mid month.
A recurring coronal hole should bring disturbed conditions around
October 4 through 7.
/EX