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ARRL Propagation Bulletin ARLP005 (2012)

ARLP005 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 5  ARLP005
From Tad Cook, K7RA
Seattle, WA  February 3, 2012
To all radio amateurs 

ARLP005 Propagation de K7RA

Here are some yearly averages this bulletin neglected at the
beginning of the year.  These are the average daily sunspot numbers
for whole calendar years, from 1994-2011: 48.1, 28.7, 13.2, 30.7,
88.7, 136.3, 173, 170.3, 176.7, 109.2, 68.6, 48.9, 26.1, 12.8, 4.7,
5.1, 25.5, and 29.9. You can see from these numbers that the minimum
between Cycles 22-23 centered around 1996 was over quickly. But the
next minimum before Cycle 24 centered around 2008-2009 was much
longer. In 2011 we were back near the levels we saw in 2006, 1997
and 1995.

Also note that from 2009-2010 the average daily sunspot number
increased by 400% (multiplied five times), but from 2010-2011 it
moved up only 17.3%.

The 3-month moving averages of daily sunspot numbers, centered on
January through December 2011 are: 35.3, 55.7, 72.3, 74.4, 65.9,
61.5, 63, 79.6, 98.6, 118.8, 118.6 and 110. The value centered on
December 2011 is the average of the daily sunspot numbers from
November 1, 2011 through January 31, 2012, and the value centered on
November 2011 includes all daily sunspot numbers from October 1,
2011 through December 31, 2011.

Over the past reporting week - January 26 through February 1 - the
average daily sunspot number declined nearly 37 points to 62.
Average daily solar flux was off nearly 21 points to 120.4. On
February 2 the sunspot number and total area of sunspot regions was
the same as February 1. The noon flux measurement moved from 117.5
to 118 from February 1-2.

Predicted solar flux for the near term is 120 on February 2-5, 110
on February 6-9, 150 on February 10, 155 on February 11-13, 150 on
February 14-19, and 145 on February 20-23.  The forecast in
mid-January for flux levels at 165 on February 17-21 are but a
distant memory.

Unfortunately, for some reason predictions updated for Thursday were
not yet available early Friday, February 3, so the numbers in the
previous paragraph were not updated since Wednesday, February 1. But
you can still get the latest prediction from

The 20 point difference in predicted solar flux should be a
noticeable difference. Although this is not an accurate prediction
method, for comparative purposes I ran a W6ELprop forecast for
February 19 from the center of the USA to Hungary with a solar flux
of 145, and then again at 165. On the higher frequencies in
particular, paths would not be as reliable nor openings as long as
with the higher value.

There is a new updated NASA prediction for the peak of the current
cycle issued early this morning.  The previous update was on January
3. There is no archive of past predictions online, but I can tell
you that the prediction for the peak of Cycle 24 is still for a
smoothed international sunspot number of 96, but it has moved from
February 2013 to late 2013.

NASA gives a detailed explanation of the models they use for
predicting the peak of the cycle, and you can read it all at  Also see the graph
at for a
revised solar flux prediction.

Shortly after the last bulletin was released last Friday, January
27, at 1837 UTC a powerful X-class solar flare was released, but not

In case you missed it last week, Science Friday on NPR ran a
fascinating story on space weather, and they spoke with astronomer
David Hathaway of NASA and astrophysicist Doug Biesecker of NOAA.
You can hear the broadcast from an archive at

They mention ham radio and effects on shortwave radio propagation,
and Biesecker gives a fascinating account of Carrington's
observation of a solar flare and how it caused the great magnetic
storm of September 2, 1859, in which aurora was observed worldwide.

An Alaska news site ran a story on photography of aurora.  Read it

There were two similar articles on the formation of sunspots this
week. One was at,
the other:

We received a nice note from Ed Richmond, W4YO of Harbor Island,
South Carolina (EM92): "The evening of Friday, January 27 into the
28th was extraordinary here. At about 0145z I came into the shack to
take a last check on band activity before hitting the big switch,
checked the DX cluster for activity on 6 meters and saw a whole lot
of TEP activity.  I turned on my rig and immediately heard ZP6CW
calling CQ, weakly.  I called him with no luck. Tuning around, I
heard a bunch of PYs and LUs. Wow! My first experience with
transequatorial propagation after four years of being on the band! I
heard PY1ZV calling CQ, called him, and he came back to me!  Next it
was LU1FAM, followed by LU5FF, PY2XB, ZP5SNA, and CX9AU. Others
heard, but not worked.  The amazing thing about it is my station; a
barefoot FT920 with an indoor dipole beneath the roof at about 35
feet. I was so juiced for the rest of the evening, I couldn't fall
asleep until after midnight!"

A week ago (January 27) Julio Medina, NP3CW of San Juan, Puerto Rico
sent a message about some 6 meter excitement: "Today, January 27,
2012 at 1913 UTC I worked HK0NA (Malpelo Island) on 50.110 MHz. The
signal was 5x9 +30 dB in FK68, and had good propagation with him for
about 2 hours. Also propagation to USA, HP1AC (Panama), 9Y (Trinidad
and Tobago), BM (China), and CO (Cuba). We had tropo and sporadic-E,
also saw television from Cuba. Other locals that worked HK0NA were
KP4EIT, WP4U, KP4ED, WP4LUU, WP4JCF, and WP4NIX among others.  This
is a new country for me on 6 meters."

HK0NA is a DXpedition to Malpelo, which is an 86 acre island lying
235 miles off Columbia's Pacific coast, and about 225 miles from
Panama. The DXpedition web site is and you can
read about and see photos from a 1969 expedition at

The outlook for the week is low solar activity.  When looking at the
STEREO site at on Friday morning I see
little activity save for a bright, complex geomagnetic signature at
180 degrees longitude, on the far side of our sun from Earth.

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 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 January 26 through February 1 were 55, 39, 34,
74, 76, 71, and 85, with a mean of 62. 10.7 cm flux was 128.2,
141.7, 114.5, 109.8, 114.4, 116.5, and 117.5, with a mean of 120.4.
Estimated planetary A indices were 6, 7, 5, 5, 6, 3, and 5, with a
mean of 5.3. Estimated mid-latitude A indices were 5, 6, 6, 5, 5, 2,
and 5, with a mean of 4.9.


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