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ARRL Propagation Bulletin ARLP005 (1998)

ARLP005 Propagation de K7VVV

Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7VVV
Seattle, WA  January 30, 1998
To all radio amateurs

ARLP005 Propagation de K7VVV

Solar activity increased this week over last, but not by much.
Average sunspot numbers were up by 17 points, and average solar flux
was also higher, but by less than five points.  Average solar flux
for the previous 90 days rose from 96 to 97, and the daily flux was
above the average for that day on five out of seven days.  This
indicates a moderate general upward trend in solar flux values.

Solar flux peaked at 108.3 on Sunday, but is now headed down to the
low nineties.  For January 30 through February 1 flux values are
projected at 94, 93 and 91.  A Coronal Mass Ejection earlier on
January 25 should cause unsettled conditions on the last two days of
January, but the A index is only expected to rise to around 20.
This is enough though to cause problems over polar radio paths and
in higher latitudes.  Solar flux is expected to bottom out around 90
between February 5-9, then rise up near 100 again later in the

Sunspot Numbers for January 22 through 28 were 37, 57, 88, 104, 99,
98 and 89 with a mean of 81.7.  10.7 cm flux was 93, 96.9, 97.5,
108.3, 100, 100.8 and 96.6, with a mean of 99, and estimated
planetary A indices were 4, 3, 4, 9, 3, 6, and 2, with a mean of

The January, 1998 issue of Scientific American has an interesting
article on the Ulysses mission, which is returning new data on high
latitude solar magnetic fields.  NASA has a web site for this
mission at

Another NASA project of interest to solar observers is the Advanced
Composition Explorer (ACE), launched last summer.  The February,
1998 issue of Monitoring Times magazine has an informative article
on solar weather and the ACE mission.  The Goddard Space Flight
Center ACE web site is at


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