ARRL

ARRL Propagation Bulletin ARLP027 (1998)

SB PROP @ ARL $ARLP027
ARLP027 Propagation de K7VVV

ZCZC AP27
QST de W1AW
Propagation Forecast Bulletin 27  ARLP027
From Tad Cook, K7VVV
Seattle, WA  July 5, 1998
To all radio amateurs

SB PROP ARL ARLP027
ARLP027 Propagation de K7VVV

Solar activity was up last week, with average sunspot numbers
increasing from about 70 to around 120, and average solar flux up
about 16 points.  On June 26 a big geomagnetic disturbance was
triggered by solar flare activity, and the planetary A index rose to
48, with planetary K indices as high as seven.  N7DB reported
significant auroral propagation on six and two meters as a result.

Over the next few days, Friday through Sunday the solar flux is
predicted to be 120, 118 and 116, with planetary A index of 12, 15
and 15.  Geomagnetic activity should continue unsettled through this
weekend, and solar flux should drop to 110 by the following weekend.
It should rise above 120 again around July 26.

Over the past month the average solar flux did not increase
significantly compared to previous months.  The average flux for
June was 108.5, while for April and May it was 108.3 and 106.7.  The
quarter just ending had an average flux of 107.8, while the average
flux for the last quarter of 1997 and the first quarter of this year
were 94.3 and 98.8.

American and European space controllers lost contact last week with
SOHO, the Solar and Heliospheric Observatory.  This satellite has
provided a great deal of valuable data and stunning pictures of the
sun since it was put into operation in 1997, but in the early hours
of June 25 ground controllers lost contact with the craft.

Sunspot Numbers for June 25 through July 1 were 84, 99, 125, 133,
137, 127 and 126 with a mean of 118.7.  10.7 cm flux was 106.2,
109.2, 115.2, 122, 119.3, 120.9 and 126.8, with a mean of 117.1, and
estimated planetary A indices were 10, 48, 5, 5, 4, 5, and 8, with a
mean of 12.1.
NNNN
/EX