ARRL Propagation Bulletin ARLP054 (2005)

ARLP054 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 54  ARLP054
From Tad Cook, K7RA
Seattle, WA  December 23, 2005
To all radio amateurs 

ARLP054 Propagation de K7RA

Average daily sunspot numbers dropped about five points and average
solar flux was down about three points, when compared to the
previous week. Geomagnetic indexes were down also. Sunspot 838
currently looks the most interesting, as it is expanding rapidly and
not quite in the center of the visible solar disk, which is the area
that has the most effect on the Earth.

The predicted solar flux for the next few days is around 90,
slightly higher than it has been recently, but only by a few points.
Sunspot 838 is growing rapidly, but will probably not emit any solar
flares. The planetary A index for December 23-26 is predicted at 7,
7, 10 and 7.

Alan Dujenski, KB7MBI of Woodinville, WA sent a link he found to an
interesting PowerPoint presentation on propagation. It is a little
easier to give the URL for the main page of the site, which is, the web site of the ARRL South Carolina
section. You can find the presentation in both PowerPoint and Word
formats by clicking on "Technical Presentations by N4UFP." In
addition to other interesting presentations, you'll find one titled
"HF Radio Propagation." Click on that link, and you will be taken to
the link that Alan sent.

More 10 meter propagation notes, but this goes back to the recent 10
meter contest. Don Strong, W7IUO from Preston, Idaho (isn't that the
little burgh where "Napoleon Dynamite" was filmed?) wrote that
during the contest he worked VK, ZL and KH6 around 1900z (I assume
both days?) and worked W2 and W3 stations from 1800-1930z. Being in
Idaho, he was in hot demand as a multiplier. I believe he did all of
this by loading into 40 and 80 meter dipoles.

Red Haines, WO0W (the second character is an O, the third is zero)
of Minnesota sent in some links to ionospheric maps created with
ionosonde data. Red wrote:

"Look at and its links for maps
of ionospheric condition, foF2 etc, derived from ionosonde data.
These maps are experimental and they map foF2 to the MHz, not very
high resolution. They display the locations of the ionosondes from
the data for the maps are derived."

He goes on to say, "Look at and its links for
data, foF2, foFes, and more, from individual ionosondes.  Data is,
of course, history by the time we can read it. In this case, it is
40 minutes or more old. This site identifies the 'sondes from which
the above referenced maps are derived."

Red continues, "While these sites are specific to North America, the
links connect to similar products for the rest of the world."

He reminds us also that MUFs based on prediction techniques are
forecasts, while the actual ionosonde readings tell us what really
happened. The forecasts tell us what might happen, and what is

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for December 15 through 21 were 47, 47, 45, 45, 63,
53 and 45 with a mean of 49.3. 10.7 cm flux was 87, 85.8, 85.2,
85.6, 89.5, 87.8, and 86.5, with a mean of 86.8. Estimated planetary
A indices were 2, 5, 5, 3, 8, 16 and 8 with a mean of 6.7.
Estimated mid-latitude A indices were 2, 3, 2, 2, 6, 11 and 5, with
a mean of 4.4.