QST de W1AW
Propagation Forecast Bulletin 38 ARLP038
Seattle, WA September 8, 1995
To all radio amateurs
SB PROP ARL ARLP038
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.