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03 November, 2007
Average daily solar flux and sunspot numbers were unchanged from last
week. The average sunspot number was easy to figure, since there were
none.
Average daily solar flux was essentially the same, 67.3 and 67.2. Since
this is a new month, it is time to go over some monthly sunspot averages.
But more about sunspots later.
A big surprise this week was last weekend's 15 meter activity during
the CQ World Wide DX Phone Contest. We've recently reported 10 and 15
meter activity that seemed surprising for the bottom of the solar cycle,
but openings on Saturday and Sunday, October 27-28 seemed to have little
precedent.
N3RD and KC1XX worked 139 and 150 countries respectively in the contest,
all on 15 meters. All this with still no sunspots.
Dave Hawes, N3RD of Phoenixville, Pennsylvania (about 25 miles northwest
of Philadelphia) wrote, "The band opened strongly to Europe both
mornings, but from the East Coast, there were virtually no eastern Asians
to be had, with only one JA logged here. Several VKs and ZLs made it through,
as did A35, V7, KH6, and FO. KL7RA squeaked through with an ESP level
signal. Of course, the N-S path provided many strong signals, and there
was a good showing from Africa and the Middle East as well. If this is
what no sunspots is like, I can hardly wait for some to show up. There's
no meters like 15 meters!"
I should point out though that N3RD used an array of three stacked 5-element
Yagis. And KC1XX, the station that worked 150 countries on 15 meters,
has an even more impressive antenna installation, which you can see at,
http://www.kc1xx.com.
We've commented recently that the recent 10-meter activity is a surprise
at the bottom of the cycle, but another opinion was put forward by Bob
Adams, W7UH of Bryantown, Maryland. Regarding north-south propagation
on 10 meters, he wrote, "In the 55 years I have been listening and
working 10-meters, this is not unusual. In fact it's quite common. People
should pay more attention to their logbooks and their memories. North/South
propagation is quite common on 10 meters from all parts of the U.S. to
Central and South America and the Caribbean."
Carl Luetzelschwab, K9LA commented, "I think Bob, W7UH summarized
his 10-meter experiences very well. I think the bands are open a heck
of a lot more than we realize - and when a contest comes along, it really
shows."
Carl also commented that, "we have to remember that sunspots are
not the cause of F2 region ionization - it's radiation at wavelengths
between 10 and 100 nm (nanometers). Sunspots, just like 10.7 cm solar
flux, are proxies for the true ionizing radiation."
Carl continued, "The closest measurement we have is the GOES X-ray
data at 0.1 to 0.8 nm in the Weekly Report put out by the Space Weather
Prediction Center, and those wavelengths impact the D region. When the
next report comes out Tuesday evening, we'll see if there was any increased
radiation in the 0.1 to 0.8 nm band - that could indicate we had increased
radiation in the 10 to 100 nm band."
There wasn't the expected increased radiation at .1 to .8 nm. Carl wrote,
"If there wasn't an increase, it was probably a combination of moving
into northern hemisphere winter and some geomagnetic activity that enhanced
the mid and low altitude F2 region."
Jack Emerson, W4TJE of Fancy Gap, Virginia works 15 meters with a 7-element
Yagi at 100 feet and a 5-element Yagi at 75 feet. He wrote, "Maybe
my set-up on 15 meters is giving me a head-start, but over the past month
many other East Coast stations have discovered that 15 has reawakened
as well. What we have been hearing is much more than the seasonal improvement
we always get this time of year, though that surely is helping. Listening
to the band over the past month at my QTH, you would think we were closer
to the top than to
the bottom. I'm not exaggerating. I have filled log page after log page
with Europeans and Mid-East stations on phone and CW. But hearing the
JA on 15m this past weekend, with the solar flux at 68 I think, that takes
the cake. Though he was too weak for me to work, I did hear stations as
far east as W9 working him."
Here at K7RA, I went out mobile on Sunday with a set of monoband whips,
and worked several Caribbean and South American stations before discovering
that I was using the 10 meter instead of the 15 meter antenna.
We received many other reports from people surprised at the
no-sunspot propagation on 15, as well as 10 and 12 meters. It may be that
we're experiencing a combination of factors, including DX stations with
great antennas, and also spotting networks that bring many stations on
the air when an opening occurs. All of this conspires to contrast our
on-air experiences with the remembered or misremembered activity of 11
or 22 years ago.
Below is the latest update on our 3-month moving average of daily sunspot
numbers. We've been tracking this in 2007 to help us spot trends that
might indicate the bottom of the solar cycle.
Dec 05 40.6 Jan 06 32.4 Feb 06 18.1 Mar 06 27.7 Apr 06 38.5 May 06 39.7
Jun 06 28.9 Jul 06 23.3 Aug 06 23.5 Sep 06 21.2 Oct 06 24.1 Nov 06 23.1
Dec 06 27.3 Jan 07 22.7 Feb 07 18.5 Mar 07 11.2 Apr 07 12.2 May 07 15.8
Jun 07 18.7 Jul 07 15.4 Aug 07 10.2 Sep 07 5.4
The average for August, September and October, centered on
September, at 5.4 is the lowest yet for this side of cycle 23. This number
was derived by adding together all the daily sunspot numbers for those
three months, then dividing the sum (492) by the number of days, which
is 92.
The straight monthly sunspot number averages for this year, January through
October, are 28.2, 17.3, 9.8, 6.9, 19.8, 20.7, 15.6, 9.9, 4.8 and 1.3.
October's average is lower than September and October of 2006, during
the minimum between cycles 22 and 23. The monthly averages for August
through November, 1996 were 20.7, 2.9, 2.3 and 25.6.
So what's next? ARRL CW Sweepstakes is this weekend. No
geomagnetic upsets are expected, but no sunspots either. This is a domestic
instead of a DX contest, with the object being to contact as many stations
in as many ARRL sections as possible. There is no provision for working
a station more than once by switching bands, so whichever band offers
the highest rate at any time is the one to be on. You can go to,
http://www.arrl.org/contests/rules/2007/novss.html
to read the
contest rules.
If you would like to make a comment or have a tip for our readers, email
the author at, k7ra@arrl.net.
For more information concerning radio propagation, see the ARRL Technical
Information Service at,
http://www.arrl.org/tis/info/propagation.html.
For a detailed explanation of the numbers used in this bulletin see,
http://www.arrl.org/tis/info/k9la-prop.html.
An archive of past propagation bulletins is at, http://www.arrl.org/w1aw/prop/.
Monthly propagation charts between four USA regions and twelve overseas
locations are at, http://www.arrl.org/qst/propcharts/.
Sunspot numbers for October 25 through 31 were 0, 0, 0, 0, 0, 0 and 0
with a mean of 0. 10.7 cm flux was 67.1, 67.5, 67.1, 67.5, 67.1, 67.2,
and 67.1 with a mean of 67.2. Estimated planetary A indices were 20, 14,
10, 7, 14, 10 and 4 with a mean of 11.3. Estimated mid-latitude A indices
were 10, 10, 8, 4, 8, 10 and 3, with a mean of 7.6.
Source: The
American Radio Relay League
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• All propagation
reports can be found at:
http://www.southgatearc.org/propagation
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