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ARRL Propagation Bulletin ARLP012 (1997)

ARLP012 Propagation de KT7H

Propagation Forecast Bulletin 12  ARLP012
From Tad Cook, KT7H
Seattle, WA  March 21, 1997
To all radio amateurs

ARLP012 Propagation de KT7H

The biggest news this week was that we are at the equinox, and hours
of daylight are about equal between the northern and southern
hemispheres.  Look for improved worldwide conditions on HF bands as
we head into spring.  Otherwise, there has been no improvement in
solar activity, with conditions last week showing no significant
change over the previous week.  Solar flux and sunspot numbers were
only slightly higher, and on four days the solar flux was just
slightly above the average of 75 for the previous 90 days.

The outlook for the next few weeks has solar flux remaining in the
mid 70s, with a rise in geomagnetic disturbances centered around
March 26 and 27.  The March 1997 issue of the magazine Scientific
American has a remarkable article about the Solar and Heliospheric
Observatory (SOHO), which is held in the point where the Earth's and
Sun's gravitational pulls are equal, some 1 million miles toward the
Sun from Earth.  There is an extensive gallery of images from the
data transmitted from the satellite on the Web at

Sunspot numbers for March 13 through 19 were 18, 43, 42, 25, 15, 24
and 0, respectively, with a mean of 23.9.  The 10.7 cm flux was
74.1, 75.5, 75.8, 75.7, 75.1, 74.3 and 73.7, respectively, with a
mean of 74.9.  Estimated planetary A indices for the same period
were 7, 4, 6, 8, 5, 6, and 4, respectively, with a mean of 5.7.