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ARRL Propagation Bulletin ARLP028 (2004)

ARLP028 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 28  ARLP028
From Tad Cook, K7RA
Seattle, WA  July 9, 2004
To all radio amateurs 

ARLP028 Propagation de K7RA

Solar flux and sunspot numbers were down again this week.  Last
week's bulletin reported average daily sunspot numbers for that week
dropped over 55 points to 60.9, and this week they dropped another
29 points to 31.9.  The lowest sunspot count was 26 on both July 1
and July 5.  Average daily solar flux from last week's bulletin was
down nearly 19 points to 94.8, and this week it is down a little
more than 15 points to 79.6.  Again this week geomagnetic activity
was quite low.

Solar activity should begin to build over the next few days.  Solar
flux values for the next few days, July 9-12, are predicted at 85,
90, 100 and 110.  Solar flux should peak near 115 around July 13-14.
Geomagnetic conditions should remain quiet, but could become
unsettled due to recurring coronal holes by Monday, July 12.  The
next unsettled period is predicted around July 27.  Recent
helioseismic images show a large sunspot group on the sun's far
side, which will soon begin to come into view.

John Reynolds, N7QF from Northern Utah wrote about an exceptional
6-meter opening on Saturday of Field Day weekend.  He worked 25
states and three countries in eight hours.  I received a similar
report from K7SS in Seattle.

NH6HE sent in a fascinating article on solar science from BBC News
titled ''Sunspots Reaching 1000 Year High''.  It talks about the
Maunder Minimum (a decades long period of no solar activity long
before the dawn of radio) and sampling ice cores for beryllium
isotopes to divine past solar activity.  You can read it at

The current July 2004 issue of National Geographic contains a
wonderful and lavishly illustrated cover article on solar activity.
You really have to see this one.  It comes with a pullout poster
illustrated on both sides.

Reader David Moore sent a link for an article about 3 dimensional
renderings of coronal mass ejections.  Read the article and view
online movies at

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at

Sunspot numbers for July 1 through 7 were 26, 33, 31, 37, 26, 39 and
31 with a mean of 31.9.  10.7 cm flux was 81.3, 80.7, 79.5, 79.4,
78.2, 78.9 and 79.3, with a mean of 79.6.  Estimated planetary A
indices were 13, 9, 9, 6, 7, 7 and 5, with a mean of 8.  Estimated
mid-latitude A indices were 9, 8, 5, 4, 5, 5 and 2, with a mean of


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