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ARRL Propagation Bulletin ARLP034 (2012)

ARLP034 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 34  ARLP034
From Tad Cook, K7RA
Seattle, WA  August 24, 2012
To all radio amateurs 

ARLP034 Propagation de K7RA

Weak solar activity continues.  Average daily sunspot numbers for
the seven days of August 16-22 were down 23 points, or 30 percent,
to 54.6.  Average daily solar flux dropped a little over 16 percent,
or 18.7 points, to 96.  These figures offer a comparison between
August 9-15 and the latest reporting period, August 16-22.
Solar flux is expected to rise above 100 soon, with predicted flux
values from NOAA/USAF at 100 on August 24-25, 105 on August 26-27,
110 on August 28-29, 115 on August 30, and peaking at 130 on August
31 and September 1.  The prediction shows September 2 with a flux
value of 125, then 120 on September 3-5, 115 on September 6-8, 110
on September 9, 105 on September 10, then dipping below 100 on
September 12-15.  The next peak is expected in the three days
following the Autumnal Equinox, with flux values at 135 on September
Predicted planetary A index values are 5 on August 24-25, then 10
and 8 on August 26-27, then 5 again on August 28 through September
7, and 8 on September 8-9, then 5 on September 10-14, then 12 on
September 15-16, 8 on September 17-18, and 5 again through the end
of September.
OK1HH predicts the geomagnetic field will be quiet to unsettled on
August 24-25, quiet to active on August 26, mostly quiet on August
27-28, active to disturbed on August 29, quiet on August 30-31,
mostly quiet on September 1, quiet to unsettled September 2-4, quiet
on September 5-7, mostly quiet on September 8-9, quiet to active
September 10, quiet on September 11, quiet to unsettled September
12, quiet on September 13, and quiet to unsettled September 14-15. reports "the Sun's x-ray output has nearly
flatlined."  Look at readings from 12 years ago, in the summer of
Now compare those numbers with recent x-ray activity:
The daily x-ray background flux is shown in the fourth column to the
right of the daily sunspot number.  Here is the x-ray flux shown in
a graph for the past few days:
The letters and numbers in the x-ray flux column in the previous two
pages correspond to the values on the right side of the graph on the
last page.  Looking back in March, May, July and September of 2000
you can see higher numbers indicated by the letter C, but nothing at
that level recently.  The background x-ray flux is a good indicator
for the level of energy from the sun charging the ionosphere.  The
more the ionosphere is energized, the higher the MUF or Maximum
Usable Frequency is in general, although the MUF varies considerably
according to time of day, season, and the end-points of the path
under consideration.
Larry Godek, W0OGH of Gilbert, Arizona wrote on August 23: "WOW!  Is
it ever all over the place today.  To start with we had a short
opening on 6 meters down TG9 (Guatemala) way.  Then I went up to 20
meters to put in some time doing the WSPR thing.  2 watts to a 4
element Yagi up 30 feet is all I use on 20.  In the time frame after
my transmit cycle I had reports from LA9, VE6, YV4, VK2, KL1 plus
other places around the USA.  The beam was pointed to about 45
degrees (northeast).  What good is a beam doing you if your signal
is going every which way?  Watching the WSPR map showed a lot of
good long haul signals."
(The WSPRnet map Larry speaks of is at  Note you can select which
band you want to observe in a drop-down below the map).
"When I worked the TG9 station on 6 meters, the beam (which is atop
the tower with the 20 meter beam) was also pointed off to the
northeast.  That's where his signal was strongest."
"Working 40 meters today around 2 PM (Arizona time) the band got
really noisy with QRN.  Signals were still good though and then the
QRN went away.  Since then signal strength has swung all over the
place.  Not slow drawn out QSB but fairly quick acting changes.
This morning on 40 we had real short propagation to the southeast
part of the state, no more than 150 miles.  Then it swung around to
where normal east-west signals became more prominent and the fellows
southeast of here were out of the picture.  Nothing really special
about the K, A or SFI index at the time."
"I'd suggest folks take a look at that WSPRnet map when they go
looking for DX.  While it doesn't show every country on the air, you
can at least get an idea of where propagation is good toward.  Nice
map features as well."
Thanks, Larry!
Jon Jones, N0JK had a comment in response to Randy W7TJ in last
week's bulletin.  Jon wrote, "My opinion is solar cycle 24 will
probably be a two-peak cycle.  First peak was fall of 2011.  The
second peak hopefully spring of 2013.  Agree with Randy W7TJ --
enjoy the propagation this fall and spring of 2013.  This may be as
good as it gets on 10 meters and 6 meters for many, many years."
John Van Dalen, N7AME of Everett, Washington wrote: "I have to agree
with Randy Crews, W7TJ of Spokane.  The DX activity for the Seattle
area has been dismal.  I only have small windows to operate right
now and they are 0200-0400z each evening and most weekends.  I look
at the spotting sites on the internet and Europe and Russia are
having a great time as is most of the east coast.  Oh for a solar
cycle like 22 or 23."
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 at  For an explanation of
the numbers used in this bulletin, see  An archive of
past propagation bulletins is at  Find more good
information and tutorials on propagation at
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Instructions for starting or ending email distribution of ARRL
bulletins are at
Sunspot numbers for August 16 through 22 were 34, 42, 56, 69, 52,
64, and 65, with a mean of 54.6.  10.7 cm flux was 98.3, 95.1, 97,
96.2, 96.2, 94.2, and 94.8, with a mean of 96.  Estimated planetary
A indices were 11, 10, 11, 12, 12, 7, and 6, with a mean of 9.9.
Estimated mid-latitude A indices were 10, 11, 11, 10, 11, 7, and 6
with a mean of 9.4.


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