ARRL

ARRL Propagation Bulletin ARLP037 (1998)

SB PROP @ ARL $ARLP037
ARLP037 Propagation de K7VVV

ZCZC AP37
QST de W1AW  
Propagation Forecast Bulletin 37  ARLP037
From Tad Cook, K7VVV
Seattle, WA  September 11, 1998
To all radio amateurs 

SB PROP ARL ARLP037
ARLP037 Propagation de K7VVV

Solar activity still remains fairly high.  The average solar flux
for the past week declined a little over 8 points, but the daily
value actually peaked again on Sunday at 164.6.  The average solar
flux for the previous 90 days went up another two points to 124, and
the solar flux on every day last week was above this level,
indicating a continued general upward trend.  Geomagnetic conditions
were stable, so HF operators enjoyed good propagation.

Solar flux is expected to decline on Friday through Sunday from 140
to 135 to 130. It should then bottom out below 130 early in the
week, then rise above 145 after September 18, above 155 after
September 23, and peak below 170 from September 25 until the end of
the month.  Look for unsettled geomagnetic conditions around
September 18 and 19, caused by a solar wind stream from a coronal
hole.  These predictions are based on the previously observable
regions now rotated off the visible surface of the sun, so a burst
of new activity could raise these values.

VE2FLE sends along an interesting resource for current geomagnetic
conditions.  It is an ftp site, which can be accessed using a web
browser, and the downloaded file can be read with the same.  Check
ftp://suntwo.geolab.NRCan.gc.ca/pub/forecast/forecast.gif to see
current geomagnetic activity in the sub-auroral, auroral and polar
zones.  In addition to current and recent activity, it also provides
forecasts.

Sunspot Numbers for September 3 through 9 were 117, 73, 101, 142,
138, 164 and 156 with a mean of 127.3.  10.7 cm flux was 162.7,
154.7, 154.3, 164.6, 151.2, 153.5 and 145.3, with a mean of 155.2,
and estimated planetary A indices were 9, 7, 6, 6, 7, 11, and 8,
with a mean of 7.7.
NNNN
/EX