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ARRL Propagation Bulletin ARLP023 (2012)

ARLP023 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 23  ARLP023
From Tad Cook, K7RA
Seattle, WA  June 8, 2012
To all radio amateurs 

ARLP023 Propagation de K7RA

Average daily sunspot numbers increased about 60% during the past
week (May 31 through June 6), when compared to the previous seven
days (May 24-30). The increase was 48.5 points, from 81.9 to 130.4.
Average daily solar flux was up 18.6 points from 111.6 to 130.2.

The increase in activity began June 1.  On May 29 the daily sunspot
number was 73, with four sunspot groups visible, 1486, 1488, 1490
and 1492. On May 30, the size of groups 1486, 1488 and 1492
diminished, but 1490 grew, and the sunspot number was 78. On May 31
sunspot groups 1486 and 1488 disappeared, and new groups 1493, 1494
and 1495 appeared.  The daily sunspot number was still about the
same, 76.  On June 1 three new groups appeared, 1496, 1497 and 1498,
and the daily sunspot number jumped to 151, and the next day the
sunspot number was 113.

On June 3 sunspot group 1499 appeared, the sunspot number was 133,
and on June 4 three more sunspot groups arose, 1500, 1501 and 1502.
Two groups disappeared, 1490 and 1492, and the sunspot number jumped
again, this time to 155, the high for the week and the highest since
May 14 when it was 156.

On June 5, group 1492 emerged again (briefly), 1495 and 1501 faded,
and new sunspot group 1503 appeared. The sunspot number was 154,
about the same as June 4. On June 6 groups 1492 and 1500
disappeared, and the sunspot number dropped to 131. On Thursday,
June 7, the daily sunspot number dropped to 98, and sunspot groups
1502 and 1503 were gone.  Solar flux also made a big drop, from 140
on June 6 to 128.2 on June 7.

Actually the noon solar flux on June 6 at the observatory (in
Penticton, British Columbia) was 151.9, but because NOAA reported it
as 140, from past experience we know that the higher number was an
outlier, a value indicating that the 2.8 GHz receiver at the
Penticton observatory must have been overwhelmed with radiation,
perhaps from solar wind, that made accurate measurement of solar
flux difficult. This is similar to front-end overload in a receiver,
when a strong nearby signal swamps the input.

you can examine the raw numbers from Penticton.  There are three
readings per day at 1700z, 2000z and 2300z.  The local noon (2000z)
reading is the official solar flux value for the day.  Judging from
the readings just before (138.7, 133.6 and 132.7) and just after
(134.5, 131.4 and 128.2) the June 6 noon reading, an estimated value
of 140 seems generous.

Compare these readings to the solar flux numbers in the NOAA table
of values at and you
can see how the Penticton flux values resolved at one digit past the
decimal point are presented as whole numbers.

There are some nice photos of the observatory at Penticton in a 2011
presentation by astrophysicist Kenneth Tapping at

Geomagnetic activity peaked on June 3, when the planetary A index
was 19, and the high-latitude college A index was 33.  The activity
continues, with the planetary A index on June 4-6 at 16, 17 and 17,
and the predicted planetary A index for June 8-11 at 8, 5, 10 and
10, followed by 5 on June 12-17. Geomagnetic activity is expected to
increase again, with a predicted planetary A index on June 18-20 at
15, 12 and 8. For June 21-25 a planetary A index of 5 is expected,
followed by another peak at 15 on July 1 and again on July 15.

Predicted solar flux is 130 on June 8-10, 135 on June 11, 130 on
June 12, and 125 on June 13-15, 115 on June 16-18, and 110 on June

The recent geomagnetic activity was caused by a coronal hole, an
opening in our Sun's magnetic field allowing solar wind to spew

Petr Kolman, OK1MGW of the Czech Propagation Interested Group says
there is a "High probability of changes in solar wind which may
cause changes in magnetosphere and ionosphere, expected on June
17-18."  He also says to watch for quiet to active conditions June
8-9, quiet to unsettled June 10, quiet June 11-12, quiet to active
June 13, mostly quiet June 14, quiet to unsettled June 15-16, quiet
to active June 17, mostly quiet June 18, active conditions on June
19, quiet to unsettled June 20-21, mostly quiet June 22-23, and
quiet to unsettled again on June 24-27.

You've heard of the glory days of Cycle 19 (maybe you were on the
air in the late 1950s?) and that the twentieth century was an
unusual period of heightened solar activity?  Well check out this
interesting piece, presented by a researcher who thinks the modern
sunspot numbers may have been inflated:

Just after last week's Propagation Forecast Bulletin ARLP022 was
posted, this came in from Mark Bell, K3MSB of Airville,

"Just a quick note on 6 meter happenings from FM19.  I've only been
on six since about 2005, but this year I've seen openings into the
Caribbean, South America, and Europe in late May which is a few
weeks earlier than typical.  On May 26 at 2231Z I worked FG8AR,
followed shortly thereafter by J69MV.  May 31 at 0049Z yielded
HK7AAG who was up and down with deep QSB.  At 1555Z on the same day
I worked Costas SV1DH in KM18.  Costas was putting out a decent
signal into the East Coast.  I emailed him after our QSO and he
reports: "Running hr 1KW RF into 7el Yagi CL6DXX CREATE and I'm on
top of a seven story building, clear to US, but have lots of Athens
city noise limiting greatly my reception and so lost many US station

And last, baby boomers (those of us born in the United States
between 1946 and 1964) of a certain age may recall the scary
early-1960s, when we lived with fear of The Bomb, and the Cold War
raged in the news. There was great fear of Russia and the Eastern
Block, and we would see occasional references in the news to the
Soviet newspaper Pravda and what seemed to us like wild propaganda.
At the same time, we saw public service announcements on television
about Radio Free Europe, transmitting a USA version of truth
(Pravda, by the way, literally translates from Russian as "true" or
"truth") to people "behind the Iron Curtain," who we were told were
hungry for an alternative to state-controlled media.  Well Pravda is
still publishing, and it turns out Radio Free Europe is still
broadcasting. Check out this wild story from RFE quoting a Russian
scientist who posits that increased solar activity correlates with
periods of heightened social unrest:

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 May 31 through June 6 were 76, 151, 113, 133,
155, 154, and 131, with a mean of 130.4. 10.7 cm flux was 117.3,
128.6, 129.1, 129.4, 128.2, 138.7 and 140, with a mean of 130.2.
Estimated planetary A indices were 10, 6, 9, 19, 16, 17, and 17,
with a mean of 13.4. Estimated mid-latitude A indices were 7, 6, 8,
16, 14, 15, and 17, with a mean of 11.9.


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