ARRL

ARRL Propagation Bulletin ARLP036 (2013)

SB PROP @ ARL $ARLP036
ARLP036 Propagation de K7RA

ZCZC AP36
QST de W1AW  
Propagation Forecast Bulletin 36  ARLP036
From Tad Cook, K7RA
Seattle, WA  September 6, 2013
To all radio amateurs 

SB PROP ARL ARLP036
ARLP036 Propagation de K7RA

Conditions were quieter again this week. Average daily sunspot
numbers declined from 77 to 69, and average daily solar flux was off
by 9.5 points to 106.9, when compared to the previous seven days,
August 22-28.

Predicted solar flux for the near term is 105 on September 6-10, 100
on September 11-12, 110 on September 13, 120 on September 14-15, 115
on September 16-17, 110 on September 18, 105 on September 19-20, 110
on September 21-22, 105 on September 23-24, and 100 on September
25-28. It then is expected to reach a minor peak of 115 on October
4-5, then 120 on October 9-12.

These predictions come from a 45-day forecast. Yesterday, September
5, the solar flux was 110.1. The first prediction for that date in
this series pegged it at 135, which maintained from July 22-28, then
105 on July 29 through August 4, 115 on August 5-11, 105 on August
12-18, 110 on August 19-28, 112 on August 29, 115 on August 30, 118
on August 31, 112 on September 1-2, and then they nailed it at 110
again on September 3-4. Note that these aren't the flux readings on
those dates. They are the predicted values for September 5, as they
varied from day to day in the daily forecast for the previous 45
days.

You can see those daily forecasts here:

http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html

The planetary A index is in the same forecast. The latest has
predicted planetary A index at 5 on September 6-8, 10 on September
9-10, 12 on September 11, 8 on September 12-14, 5 on September
15-16, then 12, 18 and 15 on September 17-19, 5 on September 20-22,
and 8 on September 23-24.

The Autumnal Equinox (September 22 at 2044 UTC) is a little over two
weeks away. Fall is always a great time for HF DX, when the sun
casts an even glow over our northern and southern hemispheres.
Although solar activity is weak, if this is Cycle 24's peak, now may
be the best time for enjoying HF propagation for some years to come.
Or the Sun could fool us again. Remember that day-to-day variations
in solar activity can swing wildly above and below any predicted
smoothed or averaged sunspot or solar flux number. But we haven't
seen much of that lately.

F.K. Janda, OK1HH offers his geomagnetic forecast. Mostly quiet
conditions September 6-7, quiet to unsettled September 8, quiet to
active September 9, quiet to unsettled September 10, quiet to active
September 11, active to disturbed September 12, quiet September 13,
mostly quiet September 14, quiet September 15-16, quiet to active
September 17, active to disturbed September 18, quiet to unsettled
September 19-21, mostly quiet September 22, quiet to active
September 23, quiet September 24-25, mostly quiet September 26,
active to disturbed September 27, quiet to active September 28,
mostly quiet September 29, quiet September 30, quiet to active
October 1, and quiet on October 2.

Last week's Propagation Forecast Bulletin ARLP035 mentioned average
sunspot numbers, but we were missing two days of data (from August
30-31) to get the complete average.  As it turns out, those two days
had low enough sunspot numbers that it actually dragged the 3-month
moving average and the monthly average for August lower.

So the three month moving averages of sunspot numbers for periods
ending in January through August 2013 were 82.8, 73.6, 80.7, 85.2,
106.4, 106.4, 97.5 and 85.6. The average daily sunspot number for
the month of August was 90.2, up from 80.2 and 86.2 in June and
July.

Thanks so much to Scott Bidstrup, TI3/W7RI in Costa Rica who sent a
link to a fascinating article in Phys.Org News and Astronomy and
Astrophysics about yet another failure to replicate earlier studies
claiming a correlation between planetary positions and solar
activity. In this case, the authors found several serious
statistical errors in the earlier analysis. Read the article and
abstract at,
http://phys.org/news/2013-09-evidence-planetary-solar.html and
http://www.aanda.org/index.php?option=com_content&task=view&id=966&Itemid=277.
Note that for a limited time, the full text of the paper is
available for free by clicking on the "Register Now" button on that
last page.

NASA has an updated prediction for sunspot Cycle 24, and like last
month, they predict the peak for Summer 2013 (that's now!) but they
have downgraded the expected smoothed sunspot number from 67 to 66.
Read it and weep at,
http://solarscience.msfc.nasa.gov/predict.shtml. They do not have
any archive of past predictions, but never fear, I have been keeping
careful track.

A year ago, they sounded an optimistic note, when the September 2012
update changed from a peak of 60 in Spring 2013 to a peak of 76 in
Fall 2013.

A month later in October it changed to a peak of 75 in Fall 2013,
then in November it dropped to 73 in Fall 2013. In December the
number was revised to 72, and in January 2013 the predicted peak was
changed to 69. February's prediction was unchanged, then March 2013
revised the peak down again to 66. April and May were unchanged, and
in June the prediction was revised upward from a peak of 66 in Fall
2013 to a peak of 67 in Summer 2013. July and August were unchanged,
and now we have the number back down a point in again to 66 in
September.

Lawrence, GJ3RAX sent us more nice VHF reports from the British
Isles. The first, in an email on August 30:

"Sporadic-E openings on 6 m are starting to become quite rare at
this time of year. I thought that the one on August 12 was going to
be the last one. I had some nice QSOs that day with IS0, OE1, F4,
HA5, OK2 and EA6. After that I did not catch any more until last
Wednesday August 28 when 6 m opened again. I then had 8 QSOs into
Germany, 3 into OK, one each with OE and SP. Those were between
1430-1545 GMT. A friend of mine told me afterwards that he was also
getting some good ones on 4 m which I did not bother to check. I
would probably have missed the opening if I was not using my IC-756
Pro 2 which I had left on 6 m with the panoramic display visible
when I glanced at it. Any signals that are strong enough to work
with SSB show up well. I do not use any of the other modes.

"The next two days also showed propagation at times. On August 29 I
had one QSO with CT1EUB at 1200 GMT. On August 30 I was in QSO with
EA7/G0WHX at 1030 GMT. The band opened again later after a QSO with
F6HRP, who is relatively local, at 1720 GMT followed by CT1FJC.

"I have not had any QSOs on the HF bands recently. I listen at times
but rarely hear anything on the bands from 17 m to 10 m which seems
very strange considering that we are at about the peak of this solar
cycle. I used to keep skeds on 17 m with friends in the USA and
Canada. My antenna on those bands is an old Cushcraft R5 at only 10
feet above the ground. On 20 m I usually hear some European activity
but often without hearing anyone speaking English. Even 40 m seems
quieter that it used to be as I used to use it as a chat band during
daytime with those in other parts of the British Isles. I have not
been on 80 m recently, even at night, and it seems to be years since
I used Top Band.

"Thanks for mentioning our VHF and Microwave groups on Yahoo. After
that both gained new members from the USA. The VHFandUHF group is
now up to 125 members."

And on September 6, another report:

"Every Tuesday evening there is a short VHF contest, organized by
the RSGB, on a different band each week. They run from 8 pm to 10:30
pm local time, now still BST. This week, on September 3, it was on 2
m and conditions were interesting. I only come on for part of the
contest each week as I never take them seriously from the
competitive point of view. This time I started shortly after 9 pm
and started with a QSO with an EI station, then G, GW and GD. My QSO
with GD8EXI was my best DX that evening at about 356 miles,
according to QRZ. After that it was all G stations apart from
exchanging notes with some of the others here in GJ. One of them had
worked up to GM but that might have been on CW. I only use SSB.

"I had heard reports of some of the more northern stations working
down to EA8. I did hear weak signal from the north of England,
towards the end of the contest, working an EA8 so I turned my beam
south but did not hear anything.

"The contest next Tuesday evening will be on 70 cm:
http://www.rsgbcc.org/vhf/.

"Wednesday morning, September 4, it was still good on 2 m and I
worked 4 stations in the south of EI where it was mostly a sea path
between us apart from a bit of Cornwall to get over. They were
between 320 and 370 miles away. I also worked into the south of GW
and a French station at about 200 miles near Paris. One of the EI
stations wanted to try 70 cm as well although he knew that he had an
antenna problem. We made it although it was rather marginal. Later
he was able to fix the problem with his antenna so we tried again in
the evening but nothing was heard. The region of high pressure had
moved and it was raining at his end.

"I have heard nothing on 6 m since the QSOs on August 30 so it looks
as if the Sporadic-E season is over and we are getting into the
tropo season.

"There is the 144 MHz Trophy Contest this weekend on Saturday and
Sunday. I am not expecting conditions to be good for that one but I
will be on for some of the time but not while I am watching the F1
motor racing from Monza."

Thank you Lawrence.

Not hearing anything on 10 meters? Check out "Tony's 10 Metre Band
Report" from G4CJC:

http://www.southgatearc.org/bands/10metres/september2013/september_05.htm#.UimEfD_VV9M.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at,
http://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.

Sunspot numbers for August 29 through September 4 were 55, 62, 60,
71, 84, 74, and 77, with a mean of 69. 10.7 cm flux was 108.8,
107.5, 107.5, 103.8, 105.6, 106, and 109.3, with a mean of 106.9.
Estimated planetary A indices were 3, 8, 11, 9, 10, 7, and 6, with a
mean of 7.7. Estimated mid-latitude A indices were 4, 7, 11, 10, 11,
8, and 9, with a mean of 8.6.
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