ARRL

ARRL Propagation Bulletin ARLP054 (2001)

SB PROP @ ARL $ARLP054
ARLP054 Propagation de K7VVV

ZCZC AP54
QST de W1AW  
Propagation Forecast Bulletin 54  ARLP054
From Tad Cook, K7VVV
Seattle, WA  December 21, 2001
To all radio amateurs 

SB PROP ARL ARLP054
ARLP054 Propagation de K7VVV

Today is the shortest day of the year. The days are very short in
northern latitudes. Here in Seattle, the hours between sunrise and
sunset are over seven and a half hours longer on June 21 than they
are now. Check out the nighttime bands such as 160 and 80 meters.

There weren't any big upsets from solar flares disturbing last
weekend's 10-Meter contest. Unsettled conditions did appear, but not
until Monday, and then the planetary A index only went to 15.

Solar flux and sunspot numbers were slightly lower this past week
compared to the previous period. Average sunspot numbers were off by
a little over 4 points, and average solar flux was down by nearly
11. The view of the sun currently shows a few spots, with not much
activity. The current outlook shows solar flux rising slowly in the
near term, reaching a peak around December 30 through January 2.
Solar flux is predicted to be right around 215 for Friday through
Monday, and then rising slowly after that.

Even though there currently is not much activity, there is some
growth in sunspot 9742. It is rotating toward a position where it is
more earth-directed, and could threaten with strong solar flares.
There is also a group of sunspots on the sun's far side, detectable
via helioseismic holography, which could provide some more activity
when they come into view.

Sunspot numbers for December 13 through 19 were 212, 202, 198, 204,
215, 210 and 158 with a mean of 199.9. 10.7 cm flux was 220.2,
245.8, 217.8, 209.1, 205.5, 211.8 and 208.2, with a mean of 216.9,
and estimated planetary A indices were 4, 4, 11, 10, 15, 8 and 9
with a mean of 8.7.
NNNN
/EX