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ARRL Propagation Bulletin ARLP034 (2013)

ARLP034 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 34  ARLP034
From Tad Cook, K7RA
Seattle, WA  August 23, 2013
To all radio amateurs 

ARLP034 Propagation de K7RA

Solar activity picked up this week, with average daily sunspot
numbers for August 15-21 up nearly 42 points (forty-nine percent) to
126.9, when compared to the previous seven days.  Likewise, average
daily solar flux increased from 111.7 to 126.3.
The latest prediction from USAF/NOAA has solar flux at 130, 125,
120, and 115 on August 23-26, 110 on August 27-29, 105 on August 30,
95 on August 31 through September 1, 100 on September 2, 105 on
September 3-4, 110 on September 5-8, 115 on September 9-11, 120 on
September 12-13, and 125 on September 14-16. It then drops below 100
to 95 again on September 27-28.
Predicted planetary A index is 15, 25, 20, 12, and 8 on August
23-27, 5 on August 28-30, then 12, 15 and 10 on August 31 through
September 2, 5 on September 3-9, then 10, 15 and 18 on September
10-12, 8 on September 13-14, then 5, 15, 22, 12 and 8 on September
15-19 and 5 on September 20-26.
OK1HH predicts in his geomagnetic activity forecast that August
23-24 will be active to disturbed, quiet to active conditions on
August 25, quiet to unsettled August 26, mostly quiet August 27-29,
quiet August 30, active to disturbed August 31 and September 1,
quiet to unsettled September 2, quiet September 3-5, mostly quiet
September 6-7, quiet September 8-9, quiet to active September 10-11,
active to disturbed September 12-13, quiet September 14, mostly
quiet September 15, quiet September 16, quiet to active September 17
and active to disturbed September 18.
On Saturday, August 17, 2013 the Penticton observatory recorded
solar flux values of 123.2, 149.7 and 129 at 1700, 2000 and 2300
UTC. The local noon value at 2000 UTC is always reported as the
official flux value for the day, but NOAA reported it as 125 instead
of 149.7.  They do this when the noon number appears to be an
outlier caused by overload of the 2.8 GHz receiver used to produce
these numbers. I suspect the overload was caused by a significant
and long duration M3 class solar flare, erupting from sunspot 1818
at 1824 UTC.
The NOAA estimate is produced by selecting a number somewhere
between the morning and afternoon readings.
A look at the weekly Preliminary Report and Forecast for August 5,
2013 (see shows the
most recent prediction for smoothed sunspot numbers peaking in
January and February 2014.
The Arizona Daily Star ran an interview with Matt Penn, the
astronomer who predicted the possible disappearance of future
sunspots based on weakening solar magnetic fields. Read it at
David Dary, W5ZAX of Norman, Oklahoma sent in an interesting article
about a different method for tracking the complexity of the solar
magnetic field. It posits that the sun may be more active than it
appears. Read it at
Note they give a link to the original journal article. You may be
able to access the article in the Astrophysical Journal online for
free via an account at your local public library.
Roland Anders, K3RA of Elkridge, Maryland reports on August 19: "15
meters continues to be fantastic into Indonesia from 8 am until past
1 pm EDST. Besides the many strong YB stations, in the past several
days during the 1300 to 1745Z time period on 15 I've worked JA, BY,
BV, 9M2, 9M4, V8, 9V, HS, 4S, VU, and UN. And the EU signals are
crushingly loud! But when 15 is that good to EU, it is a clue to try
12 meters. I've found 12 open in the morning hours several times in
the last week. Today, I called CQ on 12 (dead band) and worked 2 IT9
stations at 12:45Z. After some more CQs with no answers, I returned
to 15. I'm sure 12 was open to EU from time to time during the
morning -- maybe all morning, but I didn't get back to 12 until

"For the next hour I worked DX over a wide area: Starting with a
walloping signal from CU8AS, I then worked stations as far North as
TF and east to SV and HZ. But the biggest surprise was at 1644 when
I worked YB0NFL S9 over the North Pole. Arif worked a lot of EU and
NA DX over the half hour or so--that's 12 meters at midnight Jakarta
time! And, there were a couple of EU stations heard on 10 meters
when 12 was open. So, it seems like we're getting into fall
conditions on 12 and 10 meters. This much maligned sunspot cycle has
a lot to offer!"
Later he wrote: "Went back to 12 meters at 2100Z, and the band was
wide open to EU. Some stations VERY loud. Then, at 2130Z I heard JAs
answering an LU CQ, so I call CQ with beam to JA and worked seven
JAs, several very strong. Viva 12!"
Laurence, GJ3RAX from the Isle of Jersey sent this in: "I have been
following the discussions on this solar cycle and the question of
whether there will be a second peak. Looking at the graphs of the
previous ones I interpret them as all having a second peak even if
it is not as well defined as in the more recent 2 cycles. Obviously
the graphs do show that the second peak is normally weaker than the
first one. The shape of the present one looks as if that trend is
going to be followed although it is often dangerous to make such
"You have probably seen the same predictions that I have suggesting
that Cycle 25 will be even weaker and some think it could be
virtually flat. Looking at the historical information it does seem
to do that about every 100 years."
"The conditions on the HF bands have been so poor with my rather
minimal antenna system that I have not been able to resume skeds
with my friends in the USA and Canada. Those used to be mainly on 17
meters. Instead we have been catching up in person when some of my
friends have come over here to visit me! That is partly why I have
now gone back on the VHF and UHF bands instead."
"From what I can recollect of the recent cycles I think that the
best conditions each time on the 6 meter band have been during the
second peak rather than during the first one. This year I have been
using a rather low gain log periodic antenna covering 50 MHz to
1,300 MHz. Photos are on my entry. I have had QSOs with 39
countries on 6 meters so far this year and all were on SSB. I keep
thinking I should learn Morse or try some of the digital modes. Most
of those have been within Europe and North Africa (EA8, EA9 and
CT3). On the second of this month I was on during the only
transatlantic opening I have caught this year. I worked VE1YX and
five in the USA. My radio on 6 meters is the IC-756 Pro 2."
"A few weeks ago I got back on the 4 meter band after an absence of
about 30 years. There are now many more countries on the band than
when I was first on. My score this year is now 11 countries although
I could have got a lot more if I had been on earlier in the Sporadic
E season. I am using a Spectrum transverter, with 20 watts out,
driven by an FT-817."
"On 2 meters I have had 9 countries, 70 cms 7 countries and 23 cms 5
countries this year all using an IC-910X. Last year I was able to
work into Germany on all three of those bands during November when I
had just got back on those bands. I have worked Germany this year on
2 meters. I am hoping to be able to get more on the list when the
Tropo season starts which is usually in October."
"Earlier this year I joined the Yahoo group for the microwave bands, . That one is very
interesting but I later realized that I could not find a suitable
one for the lower VHF and UHF bands so I recently started one - . That group now has 69
members and seems to be growing nicely. We already have 3 members in
the USA so maybe we will get more from your part of the world soon."
Thanks, Laurence! Many readers may be unfamiliar with the 4 meter
amateur band at 70 MHz, which is used in Europe but not North
America. Some links to information on 4 meters:,,
For more information concerning radio propagation, see the ARRL
Technical Information Service at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are 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 August 15 through 21 were 129, 104, 96, 134,
161, 115, and 149, with a mean of 126.9. 10.7 cm flux was 122.7,
119.9, 125, 126.1, 128.3, 131.5, and 130.4, with a mean of 126.3.
Estimated planetary A indices were 15, 23, 7, 6, 5, 5, and 18, with
a mean of 11.3.  Estimated mid-latitude A indices were 15, 27, 9, 8,
6, 5, and 13, with a mean of 11.9.


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