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ARRL Propagation Bulletin ARLP045 (2006)

ARLP045 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 45  ARLP045
From Tad Cook, K7RA
Seattle, WA  November 3, 2006
To all radio amateurs 

ARLP045 Propagation de K7RA

Sunspot numbers rose over the past few days. Though the average
sunspot number for the past reporting week (Thursday through
Wednesday) was about the same as the previous week, the emergence of
sunspots 921 and 922 brought the daily sunspot number over October
29 through November 2 to 0, 15, 34, 46 and 59. This number will
probably rise through the weekend.

The increased sunspot numbers may correlate with some activity
observed for the past few days on the higher bands. A glance at on Thursday evening shows that during the day,
Asian Far East stations on 10 and 12 meters were hearing and working
the XF4DL expedition on Socorro Island (this is in the Pacific
Ocean, roughly 300 miles south of Baja California on roughly the
same latitude as Mexico City). Also apparent on 10 and 12 meters is
E51QMA in the North Cook Islands heard and worked by North American

Helioseismology detects (see a new spot emerging
on the far side of our Sun which should rotate to face us in a few
days, around November 7. Why this, when we might be only months away
from sunspot minimum, predicted to occur some time around April 2007
(see  Attribute it
to the many large short term variations we see in solar activity
during any cycle.

October is over, and we now know the average sunspot number for the
month (14.7) and the average solar flux (74.3). Here are the monthly
averages for the past thirteen months:

The average daily sunspot numbers for the months October 2005
through October 2006 were 13, 32.2, 62.6, 26.7, 5.3, 21.3, 55.2,
39.6, 24.4 , 22.6, 22.8, 25.2 and 14.7. Average daily solar flux for
the same months was 76.6, 86.3, 90.8, 83.4, 76.5, 75.5, 88.9, 80.9,
76.5, 75.8, 79, 77.8 and 74.3.

We can compare the recent monthly sunspot averages to the averages
during the last solar minimum in 1996. The monthly average sunspot
numbers for January 1996 through April 1997 were 18, 9.1, 12.1, 8.5,
11.9, 18.8, 13.2, 20.7, 2.9, 2.3, 25.6, 15.1, 8.7, 11.4, 13.7, and
24.5. We see the lowest numbers were in September-October 1996, and
six months prior to that, the numbers weren't far off from what
we've seen for the past three months, 22.8, 25.2 and 14.7.

Last week was the phone weekend of the CQ World Wide DX Contest.
Geomagnetic conditions were a bit unsettled. This weekend is the CW
weekend for ARRL Sweepstakes, and conditions should remain quiet
through the weekend, with increased sunspot numbers. Many contesters
would rather see those conditions on a DX contest weekend, but we
can't complain. The predicted planetary A index (lower numbers
indicate more stable geomagnetic conditions), for November 3-9 are
8, 8, 5, 5, 5, 5 and 20. Geophysical Institute Prague predicts
unsettled conditions for November 3, quiet to unsettled November 4,
quiet conditions November 5-7, quiet to unsettled November 8, and
unsettled to active November 9.

Larry Godel, W0OGH in Gilbert, Arizona reports that he experienced
good 10 meter FM openings last weekend to California and Texas. He
was able to work through the W5DFW repeater and another near
Yosemite in California with full-quieting signals. He comments that
on Sunday morning, "on the 40 meter AM net, local stations (those
within 100 miles) were strong as 20db over S9. Within 5 minutes they
were gone and within half an hour they were all back, strong as
ever. Conditions stayed that way for several hours thereafter."

Finally, I don't know if this fellow in Quebec is a ham operator,
but he should be. This illustrates a personal fantasy I had as an 11
year old. Problem was, it was 1963, and we didn't have the
technology yet. Take a look at these videos at, and

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,

Sunspot numbers for October 26 through November 1 were 0, 2 14, 28,
0, 15, 34 and 46 with a mean of 19.9. 10.7 cm flux was 71.9, 72,
74.7 , 73.3, 75.7, 80.1, and 86.7, with a mean of 76.3. Estimated
planetary A indices were 1, 2, 14, 21, 9, 4 and 6 with a mean of
8.1. Estimated mid-latitude A indices were 1, 3, 12, 13, 6, 2 and 5,
with a mean of 6.


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