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ARRL Propagation Bulletin ARLP015 (2009)

ARLP015 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 15  ARLP015
From Tad Cook, K7RA
Seattle, WA  April 9, 2009
To all radio amateurs 

ARLP015 Propagation de K7RA

Today the bulletin is out on Thursday, April 9, because ARRL
Headquarters is closed tomorrow on the Good Friday holiday.

Just as we reported in the last three bulletins, again there were no
sunspots this week.  In this time of the quiet Sun,
has a new feature keeping track of all these days with no spots.  On
the left side of the page at below the
image of the Sun and the current daily sunspot number, it says "New:
Spotless Days."  Early on April 9 it says "Current Stretch: 14 days,
2009 total: 89 days (87%), Since 2004: 597 days, Typical Solar Min:
485 days."

But if we show no spots in this bulletin plus the past three, that
accounts for at least 28 days, so why do the new Spotless Days
numbers say it has been 14 spotless days since the last sunspot?
The last run of sunspots we show is over two days, March 6-7, so
through yesterday, April 8, there have been 32 spotless days.

If we use the archive feature on the Spaceweather page (look in the
upper right side of the page) and go back to March 26, although
Spaceweather shows the sunspot number is zero, the text beneath the
Daily Sun image says "A proto-sunspot is struggling to emerge at the
circled location."  So if no sunspots emerge later today, April 9,
that would account for 14 days since March 26.

Recently the 45 day forecast for daily solar flux and planetary A
index at has
consistently predicted a solar flux at 70 for every day into the
future.  The last of these was on March 24.

Then on March 25 the prediction was for solar flux at 72 for March
28-31.  On March 26 that changed showing solar flux at 72 on March
28 through April 2.  On March 27 the solar flux rose to 72 (actually
71.6) and the forecast was the same, but extended the 72 number
through April 3.  Solar flux has not reached 72 since then, but the
March 28 forecast extends the reading of 72 through April 4.

On March 29 it extends to April 5, and on March 30 to April 6.  On
March 31 it extends 72 until April 9, three additional days, but it
also shows a new period with a flux of 72, April 23 to May 6.  April
1 is the same, but April 2 the flux is dropped to 71 for April 3-9.
The April 3 prediction gives up on the slightly higher flux values
for the near term, but still predicts 72 for April 23 to May 6.  The
forecast remains the same until April 7, when the 72 flux for April
23 to May 6 is shortened to April 23-29.  So it appears that even
these near term predictions for a very small increase in activity
are continually revised downward.

In the April 8 forecast, it shows the planetary A index for April
9-10 at 15 and 8, then dropping to 5 until April 21.  Early on April
9 we are experiencing the effects of a solar wind stream, and
planetary K index rose from 3 to 4 at 0300z.

Geophysical Institute Prague predicts quiet to unsettled conditions
April 10, quiet April 11-14, quiet to unsettled April 15, and
unsettled April 16.

Robin McNeill, ZL4IG of Invercargill, on New Zealand's South Island
has been on HF for about a year, and is another of many new
operators I am hearing from who are enjoying HF propagation at the
bottom of the sunspot cycle.

Robin wrote, "With the sunspots and thus the MUF as very low as they
are, surely this means that 40 meters is currently as good as it
ever gets? In fact, shouldn't 40 meters currently be as good as any
band ever gets? I base this assertion on the fact that 40 meters is
currently very close to the MUF and, as you note in the last
bulletin, there are now few QRN causing solar events."

He continues, "But that doesn't explain why only a handful of
European superstations and very few others find their signals into
ZL for hams like me on 40 meters with modest wire antennas and urban
QRM, even using the grey line. (That said, I have had a handful of
QRP SSB QSOs into Europe recently, though I was working hams who
have 3-el beams with presumably low QRM locations- one of them, in
fact, seemed surprised I was running 5 watts PEP and not 500 watts
PEP output, which surprised us both). Or have I overlooked

40 meters is a good band right now, but it isn't "as good as any
band ever gets."  When solar activity returns, the MUF will rise
enough to use the 10-20 meter bands, which typically will have less
absorption than 40 meters.  In addition, the average ham is more
likely to have greater antenna efficiency on the higher HF bands.

Another factor affecting Robin is that Europe is clear on the other
side of the planet from him.  For instance, from his location to
England is over 19,000 km (over 11,000 miles) away.  Yet Los Angles
is over 11,500 km (nearly 7,200 miles) from him.

If we do some propagation projections using W6ELprop using a
smoothed sunspot number of 3 for today, it shows a very narrow
period of strong signals over the path to England, from 1900-1930z,
when the MUF is 10.9-11.2 MHz.  A couple of hours later the MUF
briefly reaches a peak of 14.7 MHz.

But for the path to Los Angeles, a 40% shorter route, the opening is
very strong on 40 meters from 0530-1430z, and then MUF reaches a
peak of 22.4 MHz at 2330z.  In fact, toward Los Angeles, 20, 17 and
15 meters are good possibilities as well, but not on the path to

Carl Zelich, AA4MI of Chuluota, Florida sent a tip about an
interesting NASA presentation called, "NASA Science Update to
Discuss Anatomy of Solar Storms," at 1:00 PM EDT (1700z) on Tuesday,
April 14.  You can watch this live on NASA TV on the internet at  In many areas NASA TV is
carried on basic cable via academic research channels, such as the
University of Washington's UWTV in Seattle.  For the complete NASA
announcement, check

Another message in, this time from Rich Zwirko, K1HTV of Amissville,
Virginia, about the joys of the extended solar minimum and the
resulting quiet geomagnetic field.

Rich writes, "I'm now in my 4th month of retirement. I retired after
48 years in broadcasting (the last 28 at the Voice of America).
Based on what the 'experts' were saying a number of years ago, I
figured that soon after retirement I would be using the F2 layer to
add more DX countries to my 148 country total on 50 MHz.  Boy, were
the experts wrong!"

He continues, "Well, as they say, if life hands you lemons, make
lemonade. With the extended solar minimum and very low MUF numbers,
my lemonade is being made on 160 Meters. Shortly after retirement my
XYL Phyllis (K1WSN) and I moved to a new QTH in Virginia. The first
antenna to go up was a 160 meter Inverted-L. At the old Maryland QTH
I had worked 200 countries on the Topband with 100 Watts."

Rich goes on to say, "After 6 weeks of operating, five new ones have
been added to the K1HTV 160 meter low power country total. They
include K5D, CP4BT, OA4TT, T2OU and, a few days ago, VK9GMW on
Mellish Reef became 160 Meter country #205."

He ends with, "So, keep the solar minimum going. We Topband folks
are loving it!"

Thanks, Rich.  I recall some years ago when our propagation bulletin
reported constant geomagnetic storms, week after week.  Those in
higher latitudes, like much of Canada and especially Alaska, had
almost no HF communications as a result.  We've almost forgotten
what those times were like!

Check out the K1HTV bio at,

Another great and positive message, forwarded by KF7E, who says,
"this man is clearly an optimist for whom 'the glass is half full,'
never half empty. It is a refreshing viewpoint."  His friend Mickey,
K5ML of Paradise Valley, Arizona lives in a development with a
strict homeowner's association, and that means "No Antennas

Mickey writes, "Got back on the air in January '07 after being QRT
for over 2 decades. I was told that we were at the bottom of the
sunspot cycle but the cycle would be turning up soon. There has been
no significant upturn in the cycle since then. However, since
getting back on the air using a ground mounted vertical and very low
wire antennas, I've worked 206 countries and 39/40 zones. And I know
from experience that it's much easier to work DX with a beam or a

He ends with, "Like everyone else, I'd like to see the sunspots come
back. But the other day a question popped into my mind: 'When the
sunspots return, what am I going to work then that I'm not working
now?' We will work DX on higher frequencies more frequently than
now, but that's about it. I'm beginning to think all this talk about
sunspots is overrated. I'm glad I didn't wait for the sunspots to
come back before getting back on the air."

Thanks, Mickey!

See Mickey's bio and more about his antennas at,

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 a detailed
explanation of the numbers used in this bulletin, see  An archive of past
propagation bulletins is at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for April 2 through 8 were 0, 0, 0, 0, 0, 0, and 0
with a mean of 0.  10.7 cm flux was 70.6, 70.4, 70.1, 70.4, 68.8,
70.2, and 70 with a mean of 70.1.  Estimated planetary A indices
were 3, 2, 2, 4, 3, 2 and 5 with a mean of 3.  Estimated
mid-latitude A indices were 0, 2, 0, 3, 2, 2 and 4 with a mean of


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