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ARRL Propagation Bulletin ARLP038 (2011)

ARLP038 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 38  ARLP038
From Tad Cook, K7RA
Seattle, WA  September 23, 2011
To all radio amateurs 

ARLP038 Propagation de K7RA

Compared to the uneventful past few years, sunspot activity was
truly remarkable this week. Daily sunspot number for September 16
was 173, a level that hasn't been reached since over six years ago,
way back on July 5, 2005 in Cycle 23, when the sunspot number was

Solar flux reached 150.1 on September 18. Just six months ago it was
slightly higher - 153 on March 7 and 155 on March 8 - but prior to
that the only higher number was 157.3 on August 22, 2005, about 7
weeks after the sunspot number of 181.

Average daily sunspot numbers for the past reporting week (Thursday
through Wednesday, September 15-21) we up over 45 points from the
previous week to 137, and average daily solar flux rose nearly 22
points to 144.

Currently the solar flux and planetary A index forecast from
USAF/NOAA calls for solar flux of 155, 160, 165 and 170 on September
23-26, 175 on September 27-30, 130 on October 1, and 135 on October

These flux values through September 30 are quite a bit higher than
the values predicted a day earlier, and run in the ARRL Letter.

Planetary A index is predicted at 5 on September 23, 15 on September
24-25, 5 and 8 on September 26-27, 5 on September 28-30, 8 on
October 1, and 5 on October 2-7.

Geophysical Institute Prague sees quiet conditions September 23-25,
quiet to unsettled September 26-27, and quiet again on September

At 2323 UTC IPS Radio and Space Services in Australia issue a
warning of upcoming geomagnetic disturbance on September 24-25 due
to a coronal mass ejection.

You can download the latest (October) edition of WorldRadio Online
at to read this month's
Propagation column from Carl Luetzelschwab, K9LA, on pages 30-33.
This month's effort uses ray tracings from the Proplab-Pro software
( to help explain refraction,
absorption and polarization of radio signals.

Today is the Fall Equinox in the Northern Hemisphere.  In fact I am
writing these words at the exact time of the equinox, right at 0905
UTC on September 23.

Angel Santana, WP3GW of Trujillo Alto, Puerto Rico is excited about
all the new solar activity right around the equinox. He wrote,
"Almost two weeks ago I did not have much luck on the Work All
Europe SSB contest. On 20 and 40 meters I only had 77 QSOs. But last
Saturday September 17 at about 1500 UTC 10 meters exploded with
European stations. Did someone say sunspot numbers over 100, and
everybody got on the air?

"First to work was F4EZJ, then OT4A who even asked if there were a
contest, for the fast pace of the contacts. Even worked 5B4AIF and
went to 12 meters and worked EA9IB. Returned to 10 and some even
answered my call. Later at 2000 UTC went to 12 meters and worked
another bunch of Europeans. If this is a preview of the upcoming
contest period, we're in for a roll!"

Rob Steenburgh, KA8JBY says the Space Weather Prediction Center now
has a Facebook page.  Check
NW7US has a similar Space Weather and Radio Resources page at

Jeff Hartley, N8II of Shepherdstown, West Virginia wrote: "I knew it
was probably going to be a good day (September 16) when 4W6A was the
first signal heard on 21295 at around 1200Z; he was not workable,
running EUs I couldn't hear. 20 sounded fair, logging BP100 (Taiwan)
and BA8AG. Then a quick check of 15 at 1245Z showed 4W6A up to about
S4-5 and looking for 'North America only'; after several tries, he
was in the log; he was busy. By 1300Z, EU signals were loud on 15
and 12M was opening up to EU. On 12m, I logged 4K9W, OM5DP,  and
OE3GCU, then checked 10M at 1314Z to find YL2SM S7 running 4/4 Yagis
and a KW; he was getting very few CQ answers. At 1416Z I found
E21EJC in Thailand signing with a station on 28005 CW. Kob was about
S5-6 and gave me a '599, very loud' report, what a surprise!
Eventually at 1418Z, I had a nice CW run of stations on 10M as far
as the Ukraine and as far north as SP and HA and west as PA. After
checking 12M to find good signals from RA3CQ and SK2AT. Starting at
1457Z I was able to run Europeans on 10M phone with some having S9+
signals as far west as EI3JS, north to DJ8CG, and east to 9A1HDE.

"After a long break, I returned to some of the best late day 12M
conditions to EU I can ever remember. Between 1856 and 1933Z, I ran
off about 25 EU SSB QSOs including SM5FQQ and six SQ/SPs. Everybody
was loud; I never got down to the weak ones until right at the end.
Then, a check of 10M yielded a SSB QSO with EC1KR at 1935Z who was

"Saturday September 17, the Scandinavian Activity Contest CW started
at 1200Z which is only about an hour after sunrise. By 1220Z when I
fired up, OH9W is very northern Finland had a good signal on 15. OH
was the best place to be in almost all of EU for a while; LAs were
very weak and EU stations calling the OHs were much weaker than they
were, pretty ideal conditions for the contest! By 1330Z, SMs and LAs
were much better and 10M was open over a scatter path beaming 90-120
degrees over southern Africa which persisted until past 1500Z. I
managed to make 15 Scandinavian scatter path QSOs on 10; the loudest
were good copy about S3-4, but most were right near the noise level.
LN3Z and OH3MEP were the loudest. 20M at 1500Z was not very good and
the K index was rising; it is 5 as of 2000Z! 40 and 80 were horrible
to Scandinavia at 0130Z, but improved quite a bit by 0330Z. There
were some loud northern Scandinavians on 20 at 0130Z and others
reported 15M open as late as 2300Z."

Jimmy Mahuron, K9JWJ of Salem, Indiana and several other readers
sent in a link to an article from NASA Science News titled "The
Secret Life of Solar Flares." Read it at

Jon Pollock, K0ZN of De Soto, Kansas writes: "I was on 17 M this
evening (September 18) and found signals were extremely strong to
both E and W (I live just west of Kansas City) late into the
evening. I worked WA2MDF at about 9:30 PM CDT and he was running
well over S-9 with 100 W and a 170 ft. end fed long wire. About 30
min. later I worked K6GVG in San Diego at about 10:15 CDT. He was
peaking 20 dB over S-9 at times! These are some of the strongest
signals I have heard in a long time on 17 M at this hour of the
night...and from both coasts nearly simultaneously. The band was
very quiet (low noise) which usually means very long skip. I also
heard some weak JAs and VKs in the CW band. Antenna here is nothing
fancy: a 128 ft. Center Fed Zepp at 40 ft. Conditions tonight
reminded me of the 'good old days' (previous sunspot peaks)."

Fred Honnold, KH7Y of Ocean View, Hawaii (the SSW corner of the Big
Island) wrote on September 18: "Wanted to let you know we have been
having excellent TEP (Trans-Equatorial) openings on 6 meters the
last two weeks. In the last week I worked FK8CP, E51USA, A35CT, many
VK, JA, DU, VR2XMT, BA7s SI IO, and BD7OH.  During last night's
opening TV from china on 49.749 MHz was 40 dB over S9 at times. The
6 meter band was full of sync buzz for about three hours. A very
exciting evening! Seems the openings start about 0600 UTC and can
last till 1000 UTC just about every night here in Hawaii."

Reg Beck, VE7IG of Williams Lake, British Columbia (at 52.13 degrees
north latitude) wrote: "I was up in the middle of the night and
checked 12m around 0930Z on 17 Sept here in VE7. It was wide open
over the North Pole into Europe and central Asia. I logged a lot of
Europeans and some Asians in zone 17. I couldn't get through the big
pileup to JT1DX but he was loud at times. The band was up and down
with very loud signals suddenly dropping down then coming up with
flutter then clearing then flutter again then weak, etc. The opening
lasted past 1000Z then went out."

Julio Medina, NP3CW of San Juan, Puerto Rico wrote: "Today
(September 16) we had a good opening to Europe with signals from 559
to 579 on 28.050 from 1445-1737 UTC. Stations worked: OH1ND, IK1RGK,

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 15 through 21 were 167, 173, 138, 144,
128, 101, and 108, with a mean of 137. 10.7 cm flux was 140.7,
143.1, 144.8, 150.1, 140.9, 144.3, and 144.2, with a mean of 144.
Estimated planetary A indices were 5, 2, 32, 5, 3, 6, and 2, with a
mean of 7.9. Estimated mid-latitude A indices were 4, 2, 14, 5, 2,
6, and 2 with a mean of 5.


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