ARRL Propagation Bulletin ARLP004 (2008)

ARLP004 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 4  ARLP004
From Tad Cook, K7RA
Seattle, WA  January 25, 2008
To all radio amateurs 

ARLP004 Propagation de K7RA

Sixteen consecutive days with no visible sunspots, and still
counting.  This is the way it is at solar cycle minimum.  Enjoy it
now, because there will be a time in the future when solar winds are
constant and the geomagnetic field active, and although we will have
many sunspots, you may think back fondly on this time.  Particularly
for operators at high latitudes, geomagnetic instability is a
problem.  Just talk to anyone who lives in Alaska, the Klondike,
Northwest Territories or Nunavut.  They'll tell you about other
parts of the sunspot cycle, when they tune 20 meters for weeks on
end without hearing a signal.  Quiet conditions this weekend will be
good for the CQ World Wide 160-Meter CW Contest.

We've been tracking a 3-month smoothed sunspot number, and if
January ends next week with still no sunspots, the three month run
centered on December will still have an average above the previous
three months, making October the minimum.  We'll know for sure next
week, but the three month moving averages centered on June through
December should be 18.7, 15.4, 10.2, 5.4, 3, 6.9 and 7.7.  If the
no-sunspot days continue through the end of January, then the sum of
all sunspot numbers for November, December and January will be 707,
and dividing that by the total number of days for the three months
(92) yields a result of approximately 7.68478, or 7.7, the average
centered on December 2007.

The US Air Force and NOAA predict solar flux to continue around 70
through the end of this month, 75 for February 1, and 80 for
February 2-3.  Perhaps we'll see sunspots return for that first week
in February.  They also predict a quiet planetary A index of 5
through the end of this month, and then 15, 12, 10, 10 and 5 for
February 1-5.  Geophysical Institute Prague sees quiet conditions
January 25-30 and quiet to unsettled for January 31.

Among several messages this week about new vs. old cycle sunspots
was one from Neal Enault, WA6OCP of Sunnyvale, California.  He
pointed out that an old article from NASA 18 months ago gives a good
explanation of the magnetic orientation of sunspots. You can read
about it at,  Note
that southern hemisphere sunspots have opposite polarity from
northern hemisphere spots, and the polarity refers to the
orientation of the spots, from east to west.  This is presented
clearly toward the bottom of the page under, "More to the Story."

Think of those solar disk images as a mirror image of earth, so west
is on the right side, and east on the left, opposite of how we look
at a map on earth.  Picture it as though you are lying in the grass
on a warm day, with your head toward the north and feet pointed
south and your arms stretched out to each side.  As you lie there
with your eyes closed enjoying the warmth (don't look at the Sun!)
your right arm points west and your left arm points east.  If you
raise your right (west) arm and point toward the Sun's right edge,
you are pointing at the Sun's western limb.

As the Sun rotates, the spots travel from east to west, left to
right, and Cycle 23 spots in the northern hemisphere of the Sun have
north polarity to the right, and south polarity to the right in the
southern hemisphere.  Cycle 24 spots are just the opposite.

You can observe the difference in the image of spots by comparing
the southern hemisphere spots in the article linked above, to
northern hemisphere spots in this very recent article on the web at,

Neal says a good source of images to observe spot polarity is from
SOHO at,
As Neal points out, this works as long as there are spots to
observe!  Note you can click on the image to get a much closer view.
Remember that the dark side of the spot means south polarity, and
white means north.  So in the southern hemisphere look for Cycle 24
spots to have north, or white on the right side, and white on the
left in the northern hemisphere.  Also remember that we are mixing
directions and polarity in this text.  North polarity doesn't refer
to the north part of the image!

Many emails this week referred to the 40 meter moonbounce experiment
at HAARP, the High Frequency Active Auroral Research Program in
Alaska.  The subject of many wild conspiracy theories in the 1990s
(about weather control, mind control, or Tesla's secret death-ray),
last week it was used to beam powerful 40 meter signals at the Moon,
and the public was invited to listen for echoes.  Information on the
experiment is at,
Although HAARP is open to the public and performs no classified
research, you can see some of the wild claims about its alleged
secret agenda by just doing a web search on HAARP.  This isn't Area
51, after all, and the public is welcome.  Although I would never
reference them as a source, Wikipedia gives a nice rundown on the
project at,  If your collection
of QST Magazine includes the September 1996 issue, check page 33 for
an article titled "The High Frequency Active Auroral Research
Program," by K3NS.

Shelby Ennis, W8WN of Elizabethtown, Kentucky sent in a nice report
about the strong echoes he received from HAARP via the Moon, and
included a video link at of
K7AGE receiving the echoes.  The echoes seem weak at the beginning
of the program, but later become quite dramatic.

Shelby, by the way, works moonbounce on 2 meters, and has been using
meteor scatter since 1955.  At you can see
Shelby seated at his operating position, appropriately attired in a
nice tuxedo.

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, see the ARRL
Technical Information Service web page at,  For a detailed
explanation of the numbers used in this bulletin see,  An archive of past
propagation bulletins is at, .
Monthly propagation charts between four USA regions and twelve
overseas locations are at,

Sunspot numbers for January 17 through 23 were 0, 0, 0, 0, 0, 0 and
0 with a mean of 0.  10.7 cm flux was 73.7, 71.1, 70.8, 70.2, 71.6,
70.3, and 70.6 with a mean of 71.2.  Estimated planetary A indices
were 10, 10, 9, 6, 4, 2 and 3 with a mean of 6.3.  Estimated
mid-latitude A indices were 7, 10, 6, 4, 3, 2 and 3, with a mean of