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ARRL Propagation Bulletin ARLP037 (2011)

ARLP037 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 37  ARLP037
From Tad Cook, K7RA
Seattle, WA  September 16, 2011
To all radio amateurs 

ARLP037 Propagation de K7RA

Although average daily sunspot numbers are lower - down nearly 13
points to 91.7 - average daily solar flux is higher by 6.7 points
(to 122.2) and solar activity is rising rapidly.  You could see it
coming earlier this week by glancing at the STEREO mission (at when you looked at the back side of the
Sun. Lots of activity was evident, and you can still see quite a bit
more (those white patches) just over the eastern horizon, which is
on the left side of the image beyond -90 degrees.

The image of the daily Sun at shows a disc
peppered with sunspots, a welcome sight after watching the current
solar cycle appear to stall.

Numerous CME events disturbed Earth's magnetic field, and the
planetary A index record shows September 9, 10 and 12 were the most
active days, with the index at 36, 33 and 27.

The Autumnal Equinox in the Northern Hemisphere is just a week away,
September 23 at 0905 UTC, which is 5:05 AM EDT or 02:05 AM PDT.
Luckily, the increased sunspot activity should continue.

The updated prediction for solar flux and planetary A index from
USAF/NOAA sure changed from Wednesday to Thursday.  Solar flux is
predicted to be lower than earlier thought and planetary A index

Wednesday's prediction had solar flux at 145 on September 15-17, and
150 September 18-22.  On Thursday, September 15 the actual solar
flux was 140.7.

Thursday's forecast has solar flux at 140 on September 16-17, 135 on
September 18-19, 130 on September 20, and 125, 120, 120 and 110 on
September 21-24, and 115 on September 25-29.  Predicted planetary A
index is 10, 20 and 15 on September 16-18, 5 on September 19-23, 7
on September 24-25, 5 on September 26-29, and 15 on September 30.

You can compare the September 14-15 forecasts at

Geophysical Institute Prague predicts quiet conditions September
16-17, quiet to unsettled September 18, active on September 19,
quiet to unsettled September 20, and quiet again on September 21-22.

Ed Richmond of South Carolina writes, "I usually live on 6 meters
during the summer sporadic season. The propagation went downhill at
the end of August, and I more or less quit the band.  However, on
September 9, I noticed some spots on the DX reflector of an opening
into northwest South America, and decided to take a look.

"I heard an S9+ signal on CW and thought it might be a local.  When
he signed as HK7AAG (Colombia) I nearly fell off my chair. I called
and worked him, and about two minutes later, heard HC1HC (Ecuador),
not as loud but copyable. I called and worked him as well.  A few
minutes later I worked YV5ZV in Caracas. I had not expected any of
this, since September has statistically the lowest incidence of
sporadic-E propagation.

"The whole thing is even more amazing, because I live in a CC&R
neighborhood, and my 6 meter antenna is a dipole mounted about 35
feet high in the attic. I'm always amazed at what I have been able
to work with that antenna in four years on 6 meters.

"Of course, my QTH doesn't hurt either. I live on Harbor Island
(EM92sj) 14 miles out from Beaufort, SC, on a barrier island.  My
QTH is right on a salt marsh that looks out on the Atlantic Ocean.

"Will continue to check 6 meters for some TEP this month.  Hope I
get lucky."

Thanks, Ed!

Scott Bidstrup, TI3/W7RI of Costa Rica sent an article from New
Scientist suggesting that a big enough CME could deposit radiation
in low earth orbit around the earth that could persist for decades.
Scott wonders if there would be a long lasting effect on radio
propagation.  Read it at

Mike Schaffer of Tampa, Florida (EL87) monitors television
broadcasts across Central America via sporadic-E.

On September 10 he wrote, "This morning at 1436 UTC I received a
analog NTSC broadcast from Televisora Nacional, TVN-2, HOU in Panama
City, Republic of Panama via sporadic-E at a distance of 1,320 air

On September 9 Mike wrote, "At 2110 UTC on Friday, September 9, 2011
F2 propagation was noticed on NTSC analog channel 2 coming from due
south from South America.

"The first thing I noticed was what appeared to be a out of phase
sporadic-E taken place but the video would not sync lock even though
the signal was at moderate signal levels with only light fading.
Then the video appeared with warped diagonal, horizontal and
vertical scroll bars.

"The audio was almost non existent to weak with multi-path
distortion that produced a fair amount of scatter reflections. The
audio was so muffled that the TV mono speaker was not good enough.
To correct this effect stereo headphones were used.

"What struck me was that the Spanish audio dialect was not the
normal that I am accustomed to hearing from other DX propagation
modes from Mexico, Central America countries or northern coast of
South America.

"At 2135 UTC the F2 storm had peaked at my location. At this point a
manual channel scan was performed on all VHF low, high, and UHF 14,
15 and 16 channels. The results indicated the maximum usable
frequency did not exceed the audio carrier at 59.75 MHz.

"At 2203 the storm declined to a moderate state. It was at this time
a weak Spanish black & white video program appeared lasting
perhaps five seconds in duration.

"I would suspect that it was either coming from Quito, Ecuador at
1,950 miles or Lima, Peru at 2,779 miles distance because the
bearing to both cities from my QTH is at 171 degrees in azimuth.

"Minimum F2 single-hop paths can start roughly 2,000 miles and reach
a maximum of to 3,000 miles.

"At 2223 the F2 geomagnetic storm rapidly faded back to normal

On September 5 Mike wrote, "At 0001 UTC, a second northern Es event
took place on 90.1, CBC Radio 2 airing the Strombo show from
Sunbury, Ontario, Canada rushed in like a local broadcaster at 1,300
miles distance."

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 8 through 14 were 47, 65, 77, 94, 97,
118, and 144, with a mean of 91.7. 10.7 cm flux was 110.1, 111.8,
116.2, 121.3, 123.9, 129.4, and 142.6, with a mean of 122.2.
Estimated planetary A indices were 4, 36, 33, 9, 27, 17, and 4, with
a mean of 18.6. Estimated mid-latitude A indices were 2, 13, 20, 8,
17, 11, and 5, with a mean of 10.9.


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