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ARRL Propagation Bulletin ARLP011 (2013)

ARLP011 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 11  ARLP011
From Tad Cook, K7RA
Seattle, WA  March 15, 2013
To all radio amateurs 

ARLP011 Propagation de K7RA

Solar indicators were mixed this week, with the average daily
sunspot number down 8.4 points to 84.9, but average daily solar flux
up 5.9 points to 118.5. Geomagnetic indices were much quieter, with
the average planetary A index down 4.7 points to 4.4, and the
average mid-latitude A index down 5 points to 3.9. The main reason
for this is there weren't any active days this week, such as March
1-2 in the previous week's report.

The predicted solar flux for March 15-17 is 120, then 115 on March
18-19, 110 on March 20, 105 on March 21, 95 on March 22-24, 100 on
March 25-26, 105 on March 27, 110 on March 28-31, 115 on April 1-3,
then solar flux peaks around 120 on April 4-11. This prediction for
solar flux at 120 on April 4-11 is fairly recent, first appearing in
the March 11 forecast. Prior to that date, values were predicted
around 100-105, and back before February 25, 95 was the predicted
level. The predicted March 15-17 flux value of 120 is also recent.
On March 6 the predicted values were 95 for that period.

The average of predicted solar flux for the next five days, March
15-19 is 118, right around the average of 118.5 for the past
reporting week, March 7-13.

The predicted planetary A index on March 15-16 is 17 and 12,
indicating more geomagnetic activity similar to March 1-2. The
predicted planetary A index is 5 on March 17-20, 8 on March 21, 5 on
March 22-27, 18 and 10 on March 28-29, and 5 again on March 30
through April 16.

OK1HH predicts the geomagnetic field will be active to disturbed on
March 15, quiet to unsettled March 16-17, mostly quiet March 18,
quiet to unsettled March 19-21, active to disturbed March 22, quiet
to active March 23, quiet March 24-25, mostly quiet March 26, quiet
to active March 27-28, quiet to unsettled March 29-30, mostly quiet
March 31, and quiet on April 1-4.

At 0600 UTC on March 15 the Australian Space Forecast Centre
reported that a sudden impulse of 22 nT was detected in
magnetometers at 0527 UTC. Due to a CME, increased geomagnetic
activity is predicted on March 15-16. Minor storm periods at high
latitudes are possible.

The coronal mass ejection and M1 class solar flare were from sunspot
group 1692, right in the center of the visible solar disc viewed
from Earth, and was Earth-directed.

In recent online articles about a possible two-peak Cycle 24, they
were talking about the peak in late 2011 and another in 2013. But I
noticed recently that solar physicist Dean Pesnell of NASA is
suggesting a peak in late 2013 and another in 2015. Check the last
line of the first paragraph of this article posted yesterday on the
ARRL website:

Robert Elek, W3HKK sent these observations about the TX5K operation
on Clipperton Island:

"Kudos to the ops at TX5K!  And to their nifty web site. I love the
world map, spotting of call signs, almost instantaneous log updates,
QSO totals, etc. It lets you see the propagation on a visual basis,
call by call.

"I had not realized TX5K was on the air until, during our club
effort at WW8OH for the ARRL SSB DX Contest on March 2-3, we worked
them. Post-contest, and after catching up on my sleep Sunday night
and most of Monday, I turned on the rig, right after dinner, and
TX5K was EVERYWHERE, with big sigs!  I worked them on 12, 15, 17,
30, 40 and 160 meters, many bands on both SSB and CW, during an
amazing three hour stretch of operating!

"The station here is modest: 100 watts to an assortment of single
band ground planes, and an inverted L for 160m. Working them so
quickly, often on the very first or second call, was mind-blowing.
Their pile-ups were HUGE. It had to be a miracle of good timing,
plus a little experience to boot.

"I have since worked them on 160 thru 10m. Great job by TX5K!
Thanks, guys!"

For a peek at the vertical antennas at W3HKK, click the photo on the
upper right on his page at Note
you will have to log in, but accounts are free.

Brian Alsop, K3KO of Henderson, North Carolina commented that "DXers
shouldn't overlook VOACAP while chasing new ones." He sent a couple
of circuit reliability plots from his location to ZL9CI and 9M4SLL
on Spratly, and noted that the times he worked them lined up with
the predictions. "I recently downgraded to 500 watts, a 2 element
tri-bander at 40 feet and rotary dipole for 30/17/12 at 42 feet. I
need all the help I can get. Besides the DX cluster, knowing what
paths at what time may be possible helps."

K9LA has a tutorial on the ARRL web site for using VOACAP, and you
can see it at

Finally, at is a handy tool
for converting a street address into latitude/longitude coordinates.
This is useful for determining locations for propagation prediction
and other programs based on FCC database address records, or for
your own location.

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 March 7 through 13 were 80, 59, 63, 89, 105, 95,
and 103, with a mean of 84.9. 10.7 cm flux was 113.8, 115, 116.2,
119.2, 119.7, 123, and 122.9, with a mean of 118.5. Estimated
planetary A indices were 4, 3, 6, 4, 5, 5, and 4, with a mean of
4.4. Estimated mid-latitude A indices were 2, 3, 6, 3, 4, 6, and 3,
with a mean of 3.9.


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