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ARRL Propagation Bulletin ARLP038 (1995)

ARLP038 Propagation de KT7H
QST de W1AW  
Propagation Forecast Bulletin 38  ARLP038
From Tad Cook, KT7H
Seattle, WA  September 8, 1995
To all radio amateurs 
ARLP038 Propagation de KT7H
Solar activity was off a bit over the past week, with the average
solar flux down about five points from the week before, and average
sunspot numbers down by over 26.  Geomagnetic activity was mostly
low, but there was a big increase in activity over the past few days
caused by a recurring coronal hole.  The K index rose as high as
six, which indicates very disturbed conditions with dramatic
absorption of HF radio signals.
Look for another peak in disturbed conditions around September 10,
and continued low solar flux.  Flux values should rise slightly and
peak in the mid to high seventies around September 22.
Coronal holes, which are mentioned frequently in this bulletin are
areas in the coronal layer of the Sun through which an unrestricted
flow of high energy particles passes into space.  When the earth
moves through one of these streams, the geomagnetic field is
disturbed and the ionosphere is neutralized by protons.  Coronal
hole activity tends to occur more during the downward trend and at
the bottom of a solar cycle, which is where we are right now.
Sunspot Numbers for August 31 through September 6 were 18, 13, 11,
11, 23, 11 and 11, with a mean of 14.  10.7 cm flux was 75.6, 73.7,
73.3, 73.6, 74.4, 74.6 and 71.8, with a mean of 73.9.


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