ARRL Propagation Bulletin ARLP001 (2004)

ARLP001 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, K7RA
Seattle, WA  January 2, 2004
To all radio amateurs 

ARLP001 Propagation de K7RA

This is the first propagation bulletin for 2004, and time to review
averages from 2003 and compare them to previous years.  This is also
the ninth propagation bulletin posted in the last six weeks in an
effort to keep you well informed of HF conditions through the
Thanksgiving and Christmas holidays.

From the third quarter of 2002 through the last quarter of 2003, the
average daily sunspot numbers were 193.5, 152.7, 120.3, 107.3, 110.2
and 99.2.  Average daily solar flux for the same six quarters were
178.1, 164.2, 134.3, 124.2, 120.8 and 137.4.

Average daily sunspot numbers for the years 1997 through 2003 were
30.7, 88.7, 136.3, 173, 170.3, 176.6 and 109.2.  Average daily solar
flux for the same seven years was 81, 117.9, 153.7, 179.6, 181.6,
179.5 and 129.2.  We can sure see a decline in the solar cycle over
the past few years by averaging the daily numbers annually.

Over the next week, expect solar flux numbers between 120-125.  A
geomagnetic forecast for January 1 predicted planetary A index
values for January 2-8 of 20, 15, 35, 30, 35, 35 and 25.  With the
exception of this Saturday, January 3, those look like rough
conditions with geomagnetic storms, especially when the A index is
above 30.  This should be the result of a big blast of solar wind
beginning on Sunday, January 4.  Remember that long winter nights
are great for 160, 80, 60, 40 and 30 meters.  The noise of
summertime is long gone and long hours of darkness are great for the
lower frequencies, at least when there isn't a major geomagnetic

We've featured links to U.S. and Canadian sites with information on
space weather, but check from Australia.  This
is the web site for the Australian Space Weather Agency.  Click on
Space Weather to get an update on geomagnetic indices and HF fadeout
warnings.  Select HF Systems, and then look to the vertical field on
the left and click on links to ionospheric maps for Australasia,
Asia, North America, North Atlantic and Europe.

If you've ever been interested in plotting solar flux and sunspot
numbers, in the past we've mentioned Scott Craig, WA4TTK and his
free Solar Data Plotting Utility, which runs in Windows.  On New
Year's Eve, I uploaded 15 years of data for his program to his web
site.  This is nice if you haven't been running this program before
and updating the data file.  The software can pull the data out of
the bottom of this weekly bulletin and add it to the existing data
file.  It can also grab the data via FTP from the ARRL.  However, if
you have any gaps or are starting new with this program, the
complete data file through December 31, 2003 can be quite handy.
Download it if you need it, and you can add to it weekly or daily
from here on.  Get it from,
specifically at  Note that
Scott has a chart showing that he has an MSDOS version of his
program, and the Windows version runs on Windows 95 or NT4.  I've
personally used his program with Win98, Win98 SE, Win2k Pro and
WinXP Pro with no problems.

For more information about propagation and an explanation of the
numbers used in this bulletin see the Propagation page on the ARRL
Web site at

Sunspot numbers for December 25 through 31 were 58, 65, 47, 47, 56,
15 and 25 with a mean of 44.7. 10.7 cm flux was 139.1, 137.2, 161.5,
119, 114.5, 107.7 and 105.6, with a mean of 126.4. Estimated
planetary A indices were 6, 9, 12, 12, 6, 8 and 17, with a mean of