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ARRL Propagation Bulletin ARLP040 (2011)

ARLP040 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 40  ARLP040
From Tad Cook, K7RA
Seattle, WA  October 7, 2011
To all radio amateurs 

ARLP040 Propagation de K7RA

Sunspot excitement continues, with daily images of our Sun peppered
with spots.  Average daily sunspot numbers for the week were about
the same as the previous week, increasing from 96.1 to 96.7.  The
average daily solar flux dropped from 155.5 to 132.6.  Our three
month moving average of sunspot numbers puts us into activity levels
last seen in mid-2004.

September is over, so now let us look at our 3-month moving average
of sunspot numbers.  The 3-month moving averages for this year -
centered on January through August (August would include numbers
from July, August and September) - were 35.3, 55.7, 72.3, 74.4,
65.9, 61.5, 63 and 79.6.  The jump to 79.6 is a big increase. The
3-month moving average centered on June 2004 was 80.8, which was the
last time the average was near 80.

The latest NOAA/USAF forecast shows solar flux at 125 on October 7,
130 on October 8-13, 110 on October 14-16, 115 and 120 on October
17-18, and 125 on October 19-29.

The Planetary A index prediction shows 10 on October 7, 8 on October
8 and 5 on October 9-27 followed by 8 on October 28-30.

Geophysical Institute Prague predicts quiet to unsettled conditions
on October 7-8, unsettled October 9-10, and quiet on October 11-13.

The monthly sunspot maximum prediction from NASA has the next
sunspot maximum moving forward a month from May to April 2013, with
the sunspot maximum 7 points higher. Last month, the peak was
predicted to be a smoothed sunspot number of 70 in May 2013, and now
the number is 77 in April 2013.

You can read it here:

Note that these are International Sunspot Numbers, which are much
lower than the Boulder numbers reported in this bulletin.

Last week we had a report from Fred Honnold, KH7Y of Hawaii with 6
meter news. A week ago he sent this follow-up, so when he refers to
Wednesday night that is September 28 and "last night" is Thursday,
September 29. Fred writes: "Wednesday night worked 21 VK4s, very
interesting all in the 4th district. Earlier in the evening worked
LU5FF. Yesterday worked ZP5SNA, TI7/N5BEK, LU5FF, 3 PYs, no VKs or
DU. Just Central and South America. I had a YV and HC call me, but
no QSOs with them.

"Another very interesting QSO last night worth chatting about. I
worked Peter, PP5XX that is a 12,500 km path, and within a few
minutes, Peter PP5XX worked BV2DQ, long path, 20,000 km path. Not
bad for 6 meters.

"I have been trying to make sense out of the JPL TEC map and my
openings. Sure does not make sense and the timing seems to be much
different. Like I will be in a blue area with the red area going
over south America and I am still working stations. Sometimes I am
under red and so it says DU and nothing. I need to read up on this!!
That 20,000 km QSO between PP5XX and BV2DQ is exciting for sure."

The TEC map he refers to shows Total Electron Content of the
ionosphere. You can see the real-time map at

Joe Flamini, W4BXG of White Hall, Virginia writes: "Worked Cardiff,
Wales on 10M mobile on my way to work on the September 27. Worked
Puerto Rico on 10M on my way home. Wow! 'bout time!"

Bill Tynan, W3XO of Kerrville, Texas says that Sunday, October 2 was
his best day in the new solar cycle for 6 meters. He lists a bunch
of calls from South America, and notes, "Although many classify all
north/south propagation as TEP, I contend that much of it is F2.
Certainly the HCs who are north of the geomagnetic equator are NOT
TEP. On 6 meters, I run 700 W to a 50ft boom M2 at 70 ft."

TEP refers to trans-equatorial propagation.

Carl Luetzelschwab, K9LA was interviewed in a Tampa, Florida
television news story about "solar storms." Carl hadn't seen it when
reached in England, where he was headed to an RSGB convention,
perhaps to give a presentation on propagation. Read it at

RSGB has an educational web page on VHF propagation. Read it 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 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 September 29 through October 5 were 99, 89, 86,
92, 85, 126, and 100, with a mean of 96.7. 10.7 cm flux was 136.6,
138.1, 136.9, 130.9, 128.9, 130.3, and 126.7, with a mean of 132.6.
Estimated planetary A indices were 15, 8, 9, 11, 6, 6, and 20, with
a mean of 10.7. Estimated mid-latitude A indices were 16, 5, 12, 7,
3, 4, and 12 with a mean of 8.4.


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