ARRL

ARRL Propagation Bulletin ARLP032 (2001)

SB PROP @ ARL $ARLP032
ARLP032 Propagation de K7VVV

ZCZC AP32
QST de W1AW  
Propagation Forecast Bulletin 32  ARLP032
From Tad Cook, K7VVV
Seattle, WA  August 3, 2001
To all radio amateurs 

SB PROP ARL ARLP032
ARLP032 Propagation de K7VVV

Average daily sunspot numbers dropped again this week, this time by
nearly 64 points. The average daily solar flux dropped over 20
points.  On July 31 the planetary A index rose to 23, the result of
a solar wind stream. Geomagnetic activity on that day caused some
impressive auroral displays.

Solar flux is predicted to be 125 for Friday, and around 130 for
Saturday through Monday. Currently flux values are expected to rise
slowly to 140 by August 10. A holographic image of the sun's far
side taken on July 30 shows what may be a large group of sunspots,
so there may be more activity rolling around in a couple of weeks.

Geomagnetic activity could be active again on Friday, settling down
to unsettled for the weekend. The planetary A index for Friday is
predicted to be 20, and 15 for Saturday and Sunday.

With July just ended, here are monthly averages for sunspot numbers
and solar flux from the beginning of the year. Average daily sunspot
numbers, January through July were 142.7, 131, 166.7, 163.6, 135.1,
196.7 and 124.6. Average daily solar flux readings for the same
months were 166.6, 147.2, 177.7, 178.2, 148.7, 173.7 and 131.3.

There was a rise in activity during June, similar to the one around
the end of March and beginning of April, but not as high. The
monthly solar flux average for June probably beats March and April
because the high activity earlier in the year was split over the two
months.

Sunspot numbers for July 26 through August 1 were 115, 96, 88, 59,
64, 85 and 108 with a mean of 87.9. 10.7 cm flux was 123.4, 121.4,
115.5, 116.9, 114.5, 116.8 and 120.2, with a mean of 118.4, and
estimated planetary A indices were 14, 9, 5, 8, 9, 23 and 12 with a
mean of 11.4.
NNNN
/EX