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ARRL Propagation Bulletin ARLP053 (2011)

ARLP053 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 53  ARLP053
From Tad Cook, K7RA
Seattle, WA  December 30, 2011
To all radio amateurs 

ARLP053 Propagation de K7RA

This is the last Propagation Forecast Bulletin of 2011.

Average daily sunspot numbers were up over the past week, 12.3
points or about 13 percent, to 107.6. Likewise, average daily solar
flux rose 14.2 points - or 11% - to 143.1.

Predicted solar flux for the near term is about the same, 145 on
December 30 through January 6. From January 7-8 predicted flux
values are 130, then 135 on January 9-12, and 140 on January 13-15.
Solar flux is expected to peak around 150 on January 24, then go to
a minimum of 130 on January 31 through February 4.

Predicted planetary A index is 8, 5, 10, 10 and 8 on December 30
through January 3, then 5 on January 4-27, and 8 on January 28-29.

Geophysical Institute Prague predicts unsettled conditions December
30, quiet to unsettled December 31 to January 1, and quiet
conditions January 2-5.

Conditions should be good for Straight Key Night, the 24 hours in
which we celebrate our communications heritage with CW and manual
keys. See details at

Funny how these predictions sometimes turn out.  You can subscribe
to geomagnetic warnings from the Ionospheric Prediction Service,
part of the Australian Department of Industry, Science and
Resources.  They issued a geomagnetic disturbance warning at 0338z
on December 22, predicting quiet conditions prior to possible shock
arrival on December 24, active conditions possible December 25, and
unsettled to active conditions December 26.

A coronal mass ejection appeared to be in a geoeffective position,
meaning it was aimed at Earth. But apparently it missed us, and the
readings from magnetometers bear this out.  Check the A and K index
recordings at and
note all quiet around those dates. The high latitude college A index
(and the K index it is based on) from Fairbanks, Alaska was a flat
zero from December 23-28, and this is at a latitude that is most
affected by high solar activity.

You can subscribe to the IPS warnings via Similar products
are available from NOAA SWPC at

This article
( from Great
Britain's Daily Mail seems to warn of mayhem from a "massive solar

But in the body of the text, we see that NOAA's Space Weather
Prediction Center wrote: "Category G1 (Minor) geomagnetic storms are
expected 28 and 29 December due to multiple coronal mass ejection
arrivals. R1 (Minor) radio blackouts are expected until 31

And here is a worse example, although I do not know if "Romania
Business Insider" is a real newspaper, but they do list a byline for
a reporter with an email address. The article at
seems to recycle six-year-old news releases.

Note that the quote about "30 to 50% stronger" seems to be from this
news release from 70 months back:  Of course the
latest predictions say 2013 instead of 2012, weaker and not
stronger, but I have no idea where that prediction for activity as
big as Cycle 19 in the late fifties came from. The latest cycle
forecast was issued a couple of weeks back:

According to Robert Steenburgh, KA8JBY of Longmont, Colorado you can
monitor solar flare impacts on the ionosphere at Since there hasn't been
much activity of late, you can check out past conditions in the
archive at An
experimental auroral forecast is at

We don't know the precise daily average of sunspot numbers for the
calendar year, but with 99.5% of the data available, our figures are
pretty close.

Of course, a calendar year is an arbitrary period for averaging
sunspot numbers, but the yearly averages of daily sunspot numbers
for 2003-2011 are 109.2, 68.6, 48.9, 26.1, 12.8, 4.7, 5.1, 25.5 and
80.1. This is a good trend, and note that the average daily sunspot
numbers for the past 100 days (again, another arbitrary period) is
117.1, substantially higher than all of the past year, and higher
than all of 2003.

If you want to look at average sunspot numbers for every month since
January 1749 (that's 13,713 weeks) check  Note these
are the lower International Sunspot Numbers, not the NOAA values we
give here.  Also note that the current Gregorian calendar was not
adopted in the United States until three years and eight months
after the beginning of this record.  Back then, it was all Julian

Did you know that in 2011 we had only two days with zero sunspots?
In 2010 it was 51 days, and 2009 had 260 spotless days.

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 December 22 through 28 were 105, 123, 101, 66,
110, 126, and 122, with a mean of 107.6. 10.7 cm flux was 145.8,
138.2, 142.8, 144.3, 145.6, 140.3, and 144.8, with a mean of 143.1.
Estimated planetary A indices were 2, 1, 1, 1, 1, 0, and 2, with a
mean of 1.1. Estimated mid-latitude A indices were 4, 2, 2, 3, 2, 2,
and 4, with a mean of 2.7.


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