Register Account

Login Help

ARRL Propagation Bulletin ARLP046 (2008)

ARLP046 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 46  ARLP046
From Tad Cook, K7RA
Seattle, WA  November 7, 2008
To all radio amateurs 

ARLP046 Propagation de K7RA

Sunspot 1007 is still there, but probably rotating off the visible
solar disk today.  This is the eighth sunspot of the new solar cycle
-- and also the largest.

We've been posting a three-month moving average of sunspot numbers
most months, and now that October has passed, we can update the
table of averages through the month of September.  Last month the
three-month average centered on August was computed by adding
together all of the daily sunspot numbers for July, August and
September (102) and dividing that sum by the total number of days
for those three months (92).  The average centered on August is then
approximately 1.1.  For September, we did the same thing, only this
time summing all daily sunspot numbers for August, September and
October (230), then dividing by the number of days, yielding exactly

Here are the three-month averages back through the Summer of 2006:

Jun 06 28.9
Jul 06 23.3
Aug 06 23.5
Sep 06 21.2
Oct 06 24.1
Nov 06 23.1
Dec 06 27.3
Jan 07 22.7
Feb 07 18.5
Mar 07 11.2
Apr 07 12.2
May 07 15.8
Jun 07 18.7
Jul 07 15.4
Aug 07 10.2
Sep 07  5.4
Oct 07  3.0
Nov 07  6.9
Dec 07  8.1
Jan 08  8.5
Feb 08  8.4
Mar 08  8.4
Apr 08  8.9
May 08  5.0
Jun 08  3.7
Jul 08  2.0
Aug 08  1.1
Sep 08  2.5

For those who check the daily sunspot number from NOAA, the table at was unavailable
Thursday evening.  As an alternate, the quarterly table is online

The quarterly geomagnetic indices can be found at and you can see
that the past few days have been very, very quiet.  This is
something we probably won't see after the solar cycle picks up,
because solar flares and high speed solar wind are more common when
the Sun is active.

Note the numbers for the first week of November.  There are many,
many zeroes, which means less absorption and chance of ionospheric

There are eight daily K index readings, then one A index for that
day.  If the K index is 0 for the whole day, then the A index is 0.
If you saw K of 1 every three hours, then the A index would be 4, K
index reading of 2 yields an A index of 7, K equal to 3 means A
index of 15.  K of 3 and A of 15 are very common during the active
portion of the solar cycle.  In the table, there are planetary
numbers, which represents an average of readings from magnetometers
in multiple locations, mainly at higher latitudes.  The
middle-latitude numbers are readings from Fredericksburg, Virginia,
and the high latitude numbers are from College, Alaska, at the
University of Alaska near Fairbanks.

But perhaps by the time you read this, Friday, November 7 will have
a geomagnetic storm.  NOAA and the U.S. Air Force predict a
planetary A index of 30 for November 7, then 15 the next day, 8 on
Sunday, and 5 every day until November 25.

On November 4, Australia's IPS Radio and Space Services issued an
alert warning of a high speed solar wind from a coronal hole during
the period of November 5-8.  For November 7 it predicted unsettled
conditions with isolated active periods, and mostly unsettled
conditions November 8, with a chance of isolated active periods.

Michael Treister, W9NY of Chicago says that during the recent CQ
Worldwide SSB DX contest (October 25-26) he worked as many
countries, zones and stations on 15 meters as he did on 20 meters.
Michael said, "Conditions were amazing."

He wrote that on the morning of November 2 he, "worked all over
Europe with many reports that I was 5/9 plus 20 and 30 - just like
the good old days. Worked two mobile stations in Greece (they were
5/5-5/7 and Q5) and one station in southern England running 10 watts
to a dipole who was 5/5.  He was so excited about the contact that
he followed up with an e-mail to me! Most of the stations I worked
were running 50 to 100 watts and were coming in on my TH7 beam 5/7
or better.  This was really good propagation."

Michael also said that he tried 10 and 12 meters, but got no
response.  He wrote, "I have not heard signals like this on 15
meters for a couple of years."

Last week Pat Dyer, WA5IYX of San Antonio, Texas wrote concerning
the CQ Worldwide SSB DX Contest that using a 3 element Yagi at 20
feet he worked 10 meter stations, mostly in Brazil, Uruguay,
Argentina and Chile.  He said, "This is typical of the band at solar
minimum where the F2 path is double-hop without an intermediate
ground reflection (oft-called "chordal" or "trapezoidal"). The only
things from northern South America noted here were HC8 and OA. There
was a conspicuous lack of any Caribbean or Central Americans, though
I'm sure that US stations further north (so with longer skip
distances) probably had some.  They also could have had some Es
linking them into the low northern latitudes and then some F2 paths
from there."

This bulletin has mentioned the W6ELprop free propagation software
from time to time, and Carl Luetzelschwab, K9LA has a tutorial
titled "Downloading and Using W6ELprop" at,

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 October 30 through November 5 were 13, 16, 16,
17, 18, 14, and 11 with a mean of 15.  10.7 cm flux was 66.8, 68.1,
66.7, 69.1, 69.5, 68, and 67.7 with a mean of 68.  Estimated
planetary A indices were 11, 6, 1, 2, 1, 1 and 0 with a mean of 3.1.
Estimated mid-latitude A indices were 11, 5, 0, 2, 1, 1 and 0 with a
mean of 2.9.


Instragram     Facebook     Twitter     YouTube     LinkedIn