ARRL

ARRL Propagation Bulletin ARLP001 (1998)

SB PROP @ ARL $ARLP001
ARLP001 Propagation de K7VVV

ZCZC AP01
QST de W1AW
Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, K7VVV
Seattle, WA  January 2, 1998
To all radio amateurs

SB PROP ARL ARLP001
ARLP001 Propagation de K7VVV

Conditions were good for the last week of 1997 with higher solar
activity than the previous week and mostly low geomagnetic activity.
The exception was on December 30, when the global K index went as
high as six and the global A index was 25.  This was due to a
coronal mass ejection on December 26 as well as a coronal hole.  On
the last day of the year the average solar flux for the previous 90
days rose from 94 to 95, and the solar flux was above that level
each day of the week.

Average solar flux has steadily risen over this past year,
particularly in the second half.  Average solar flux for the first
quarter of 1997 was 73.8, and 73.6 for the second, 82 for the third
and 94.3 for the fourth quarter.  Look for steadily rising figures
in 1998.  (The reason that 94.3 for the last quarter is not the same
as the 95 average for the previous 90 days is that the last quarter
was all of October through December, which was actually 92 days.
The 95 number mentioned in the previous paragraph is rounded up, and
the difference in averages is only .18.)

For the short term, we should have fair conditions for the ARRL RTTY
Roundup this weekend.  There are no predicted geomagnetic
disturbances, and the solar flux for January 2-4 is forecast at 98,
93 and 90.  The latest projection shows the solar flux going down to
the mid to high eighties, then back above 90 around January 16, and
above 100 after January 21.

Sunspot Numbers for December 25 through 31 were 56, 50, 56, 55, 79,
56 and 64 with a mean of 59.4.  10.7 cm flux was 104.7, 104.7, 95.9,
102.1, 104.4, 101.3 and 104.5, with a mean of 102.5, and estimated
planetary A indices were 2, 1, 2, 2, 3, 25, and 4, with a mean of
5.6.
NNNN
/EX