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ARRL Propagation Bulletin ARLP006 (2002)

ARLP006 Propagation de K7VVV

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7VVV
Seattle, WA  February 8, 2002
To all radio amateurs 

ARLP006 Propagation de K7VVV

Average daily sunspot numbers were higher, rising 38 points over the
previous week. Solar flux continued a decline from last week, with
average daily flux down over 18 points. Solar flux for the short
term peaked January 29, and has declined since. Predicted solar flux
for Friday through Monday is 190, 185, 180 and 175. Flux values
should reach a minimum near 170 for the short term, then jump
suddenly higher around February 16. Geomagnetic conditions are
expected to be moderate.

For the past few days the earth has been in a stream of solar wind
from a coronal hole, causing some geomagnetic activity. Planetary K
indices were as high as 4. Also on February 1 there was another
solar wind disturbance commencing around 0558z which caused some
aurora activity and planetary K indices as high as 5. This is
generally bad for HF communications because of absorption,
especially over polar paths. What HF operators generally want to see
are many sunspots, such as we have currently at the peak of this
solar cycle, but without flares or the accompanying geomagnetic

Every day we receive email asking for explanations of the indices in
this bulletin and requests for basic texts. The New Shortwave
Propagation Handbook published by CQ is a good source, and also the
propagation section of any recent ARRL Handbook is useful. You can
also find an archive of back issues of this bulletin at . A good explanation for the numbers
in this bulletin by K9LA was in the first bulletin of this New Year,
Propagation Forecast Bulletin ARLP001 in that same archive. Other
issues of the bulletin will cover propagation topics of interest to

Sunspot numbers for January 31 through February 6 were 238, 256,
222, 273, 274, 286 and 226 with a mean of 253.6. 10.7 cm flux was
242.6, 245.6, 240.6, 232.9, 234.6, 220.6 and 202.5, with a mean of
231.3, and estimated planetary A indices were 5, 11, 18, 5, 6, 16
and 16 with a mean of 11.


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