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ARRL Propagation Bulletin ARLP014 (2007)

ARLP014 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  March 30, 2007
To all radio amateurs 

ARLP014 Propagation de K7RA

The daily sunspot number ended the stretch of zeroes on March 23,
after 10 days of totally blank sun. Since then the daily sunspot
number has ranged from 11 to 23. Note that as mentioned in recent
bulletins, the daily sunspot number is not the same as the number of
sunspots, but represents the number of spots and individual groups
of spots. The minimum non-zero sunspot number is 11, when there is
one spot visible.

Geomagnetic activity came a little earlier than predicted, with the
active day on Saturday, March 24. The latest forecast shows the next
period of higher geomagnetic activity on Monday, April 2. The
sunspot numbers and solar flux should remain about the same, with no
more than one or two spots visible.

Geophysical Institute Prague predicts quiet geomagnetic conditions
for March 30 and 31, unsettled activity on April 1 and 2, quiet to
unsettled on April 3, and quiet again on April 4 and 5.

Keith O'Brien, N4ZQ of Clearwater, Florida wrote in reminiscing
about solar activity from long ago:

"I had just turned 11 years old in February 11, 1958. I was about a
year and half away from getting my first, one year -- non renewable
-- 5 WPM, Novice License. My family lived on the south shore of Long
Island in the town of Merrick. But what I remember about that
particular date was a night sky that was as bright an orange as any
noon day. I recall climbing the center stairs to the second floor of
my Colonial style house to watch the fantastic sight out the north-
facing window.

"Little did I understand what I was witnessing, but probably one of
the largest auroras of modern time. I recall reading the New York
papers the next day where they talked about a large radio blackout
due to the storm.

"The light from the auroras was visible all the way south to Mexico.
It was a sight to behold and has stuck with me all these years.

"But what I would like to find, if possible, is what the surface of
the sun looked like at that time. How many sun spots were there and
how large they were?"

I found a drawing for Keith done on that day in Japan. You can see
it on the web at,
You can see other drawings from by clicking on Sunspot
Drawings in the Index, then under Drawings click on the year you
want, then you will see filenames which are the dates of the

Don Smith, N6NAX of Phoenix, Arizona writes that he is working the
world on 20 meter PSK with only three watts. He observes "KH6CW
working stations non-stop in Europe and USA" on 20 meter PSK. Even
with 0 or nearly no sunspots, he is still seeing many signals from
all over and 20 and 40 meters. He reports using a home built
vertical antenna "like the one described in October 1995 edition of
QST magazine."

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 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,

Sunspot numbers for March 22 through 28 were 0, 14, 11, 11, 17, 11
and 23 with a mean of 12.4. 10.7 cm flux was 72.5, 72.5, 72.8, 73.7,
73.8, 73.3, and 74.6, with a mean of 73.3. Estimated planetary A
indices were 2, 10, 21, 10, 11, 12 and 7 with a mean of 10.4.
Estimated mid-latitude A indices were 1, 7, 16, 8, 7, 9 and 6, with
a mean of 7.7.


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