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ARRL Propagation Bulletin ARLP013 (1998)

ARLP013 Propagation de K7VVV

Propagation Forecast Bulletin 13  ARLP013
From Tad Cook, K7VVV
Seattle, WA  March 27, 1998
To all radio amateurs

ARLP013 Propagation de K7VVV

Solar activity remained high last week.  Average solar flux for the
previous ninety days rose two points from 97 to 99.  Solar flux was
well above these values on each day, indicating a good trend upward.

Looking at a graph of both solar flux and sunspot numbers over the
past two months, a general upward trend becomes apparent.  HF radio
users can hope that the March 15 solar flux of 133 establishes a new
level of activity for the current cycle that will be sustained.  A
glance at the chart at gives a graphic
illustration of this.

March 21 saw a geomagnetic storm, with planetary A indices jumping
to 33.  This was caused by a solar flare, and within a couple of
days conditions had quieted back down.

Conditions over the next few days should be fair for the CQ
Worldwide WPX Phone Contest.  The solar flux on Friday through
Sunday is forecast to be 111, 111 and 110.  Flux levels are expected
to drop below 100 after April 1, then above 100 after April 5 and
above 110 by April 7, peaking near 120 around April 10 and 11.
Active to minor storm geomagnetic conditions are expected over April
6 and 7.

Over the next few weeks good propagation between northern and
southern hemispheres associated with spring conditions should
continue.  During daylight look for the best worldwide conditions on
15, 17 and 20 meters, and 30 and 40 meters after dark.

Sunspot Numbers for March 19 through 25 were 80, 100, 95, 114, 72,
83 and 79 with a mean of 89.  10.7 cm flux was 124.8, 126.5, 125.8,
127.6, 122, 120.6 and 115, with a mean of 123.2, and estimated
planetary A indices were 4, 7, 33, 11, 5, 7, and 16, with a mean of


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