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ARRL Propagation Bulletin ARLP053 (2009)

ARLP053 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 53  ARLP053
From Tad Cook, K7RA
Seattle, WA  December 24, 2009
To all radio amateurs 

ARLP053 Propagation de K7RA

This bulletin is coming out a day ahead of normal schedule because
of the Christmas holiday on Friday.  ARRL headquarters closes early
today for Christmas Eve at 1900 UTC.

Many of us are nearly giddy with joy over the recent steady increase
in sunspot activity, which seems long overdue. Average daily sunspot
numbers rose over 10 points this week compared to last, from 21.1 to
31.4.  The monthly average daily sunspot numbers for September,
October and November were 6.6, 7 and 7.7, so this is quite a large

Five new sunspot groups emerged since December 9, three of those
over the past week, on December 19 and 20.  These were groups 1035
and 1036 on December 19, and 1037 on December 20.  Today a new
sunspot appears to be forming, and you can see it via the Solar
Terrestrial Relations Observatory at
Look for that bright spot in our Sun's southern hemisphere, around
-65 to -70 degrees longitude.

If we consider there are twelve of these 30 degree segments on the
spinning Sun seen on the STEREO web site, considering a complete
solar rotation takes about 27.5 days, each thirty-degree segment
passes over the horizon in about 2.3 days, or every 55 hours. We
can't tell if every bright spot beyond the horizon is formed into a
sunspot, but we can roughly calculate how long it takes for a
particular area of interest to rotate into view.

Right now on early Thursday morning, December 24, I can see an
active area (number 1035) around +115 degrees longitude or so, about
25 degrees over the horizon.  We can roughly assume that it is about
155 degrees longitude away from its reappearance at the -90 degree
longitude horizon on the other side.  This should be about 11-12
days from now.  Of course we do not know if activity in this area
will increase or decrease in the next couple of weeks.

At we see a
prediction for December 24 (in the December 23 forecast) showing
predicted solar flux values of 76, 74, and 72 for December 24-26,
continuing at 72 until January 4, around the time this region
reemerges, when it rises to 75, then 77 for January 5-6, then 80 on
January 7-9, and 85 for January 10-18.

We also see steady quiet geomagnetic conditions, with planetary A
index rising slightly to 7, just for December 27-28.  Or course,
this could be wrong.  Note that in the December 16-19 forecasts the
expected planetary A index for December 20 was 15. Data from the
bottom of our bulletin shows that planetary A index for that day was
only 1.

The Winter Solstice occurred on Monday, December 21 at 1747 UTC in
the Northern Hemisphere, and days are gradually growing longer.
Spring Equinox is 179 days from today.

We've had reports from Robert Elek, W3HKK of Johnstown, Ohio in two
recent bulletins, and again he comes through with some interesting

Bob reports that John, ON4BW (Jean-Michel Debroux in Braine
l'Alleud, Belgium) is running 600 watts to a 4 element 40 meter Yagi
at 70 feet, and blasting a strong signal into North America during
his mid-day, around 1100 UTC.  Braine l'Alleud is about 10 miles
south of Brussels.  You can see a nice photo of ON4BW and the big
antenna at

Bob says, "Time and time again, strong signals are heard from Europe
2-3 hours past their sunrise here in Ohio, during the so called
dog-days of winter. The combination of a broadcast-station-free
segment of 40 meters and growing global wealth have 40 meter Yagis
popping up all over the 7.125-7.200 SSB band segment, with
corresponding big sigs from around the globe. If you haven't been on
40 SSB for a few years, you WILL be surprised at how much 40 sounds
like 20 meters used to sound. And, it only takes ONE Yagi to make
the circuit, so give them a call. W3HKK is using 100 watts to a
quarter wave ground plane just off the ground, with 6 radials."

"A reminder: This is the time to hear polar stations, north and
southern latitudes. Antarctica, KC4AAC was heard just above the
noise near 7.170 SSB, around 0100 UTC on December 20. Oleg, UU9JX/MM
was worked from the Magellan Straits on 10.110 MHz at about the same
time. Strong LU stations are regulars on 40 SSB in the evening. Plus
OX, TF have been worked in recent weeks with big signals."

On December 18 Bob reported, "Another interesting Friday night on 40
SSB. At times during the evening, the band sounds pretty quiet. More
stateside signals are being heard with the recent rise in sunspots.
And a fair number of Central America and Caribbean stations come and
go. But if you poke around, the juicy DX is there loud and clear.
I2VRN is a beacon, and several EAs also 59+ are heard. Pair of A71
stations (Juma, A71EM and Jamil, A71FJ) were taking turns working DX
on 7.130 MHz with signals around 5x9 from 0400-0445 UTC. 4L4TL
joined in for a while. Juma noted they were over 2 hours past their
sunrise and still the DX kept coming. Juma and Jamil are a couple of
very nice guys looking to spread A71 contacts around to any takers.
A71 activity on 40m has been almost daily all this week, through
December 19."

"Then, tuning up into the 7.135-7.155 MHz range, at least eight ZS
stations were heard working stateside, or rag-chewing in a morning
ZS roundtable, at 0400-0430 UTC. Again it was at least one hour past
their sunrise. ZS3D has been heard in Ohio on a nightly basis with
signals between 57 and 59+10 running 500 watts to a 2 element hex

Dick Grubb, W0QM of Boulder, Colorado used to work at the NOAA Space
Weather Prediction Center.  He sent along an article he scanned from
the current issue of Space Weather, the International Journal of
Research and Applications from the American Geophysical Union.
Titled "Slow Start to Solar Cycle Tied to Sluggish Interior Stream,"
it explains there is a slow moving river of gas deep inside the sun
which may be the reason for the scarcity of sunspots and late start
to the current solar cycle.  Sonograms show it is currently moving
much slower than normal.

The currents typically take 6-8 years to move from the poles to
equator as they spiral east to west, and for this cycle it is taking
1-2 years longer.

When the stream reaches 22 degrees latitude, a new crop of sunspots
and new solar cycle appears.  The jet stream has finally reached
critical latitudes for sunspot development, and we should look
forward to a quick up-tick in activity.  Solar activity is now
expected to peak in May 2013.

The same publication announces a Space Weather Forecasting Contest.
Unfortunately, they do not allow individual entrants without
affiliation to some educational or research institution, but the
criteria (high school students, researchers, grad students, alumni,
etc) look pretty broad, so perhaps individuals may enter after all.
Probably most of us are at least alumni of some high school,
correct?  You can see details at

The new issue of WorldRadio Online is out, at  Check pages 22-24
for Carl Luetzelschwab, K9LA's excellent monthly propagation
feature, this month titled, "Is There a Most Advantageous Band and

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

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for December 17 through 23 were 24, 20, 43, 42, 42,
26, and 23 with a mean of 31.4. 10.7 cm flux was 86.9, 84.2, 81.7,
83.7, 82.7, 82.2, and 78.4 with a mean of 82.8. Estimated planetary
A indices were 1, 2, 1, 1, 1, 2 and 2 with a mean of 1.4. Estimated
mid-latitude A indices were 2, 2, 0, 2, 1, 2 and 3 with a mean of


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