ARRL

ARRL Propagation Bulletin ARLP046 (2009)

SB PROP @ ARL $ARLP046
ARLP046 Propagation de K7RA

ZCZC AP46
QST de W1AW  
Propagation Forecast Bulletin 46  ARLP046
From Tad Cook, K7RA
Seattle, WA  November 13, 2009
To all radio amateurs 

SB PROP ARL ARLP046
ARLP046 Propagation de K7RA

Sunspot region 1029 disappeared after October 30, but not because it
faded away.  It was transiting over our Sun's western horizon on its
trip around the back side.  Six days after it was gone a new region
1030 appeared for several days, November 5-7.  On November 8 region
1030 had faded away and seemed like other weak spots we've seen over
the past couple of years, except they appeared for one day with a
sunspot number of 11.  Sunspot region 1030 ran for three days with
sunspot numbers of 15, 16 and 11.  But then on November 9 the
sunspot region re-emerged, with sunspot numbers of 14, 13, 11 and 11
through November 12.

While 1030 is passing over the western limb, we can still see
sunspot region 1029 transiting the far side of our local star, and
now it is approaching the eastern horizon.  A short time ago this
observation would have been impossible, but with the STEREO mission
(see http://stereo.gsfc.nasa.gov/) our total vision of the Sun now
approaches 85%.

Old region 1029 appears as a bright area of magnetic disturbance,
and we can't actually determine what the sunspot number or the total
area of the region might be, but it still appears to have a large
and robust magnetic signature.

The 45-day Air Force and NOAA Ap and flux forecast gives us some
clue about the dates it may emerge into view, and when it is most
directly facing Earth.

Predicted solar flux is 73 for November 13, 74 on November 14, 75 on
November 15-21, and 80 for November 22-24.  After that the forecast
shows it declining to 75, 72 and 70.  This suggests it might reach
the most geoeffective position, that is, the position where it is
near the Sun's central meridian relative to the Earth, around
November 22-24.

Conditions have been good, with continued weak or missing solar
wind, and very quiet geomagnetic indicators.  As noted in previous
weeks, a check of geomagnetic data at
http://www.swpc.noaa.gov/ftpdir/indices/DGD.txt shows day after day
with K index values at 0, which is as low as it can go.  During past
times and previous cycles, it was common to see a constant K index
of 3, and A index of 12-15 for mid-latitudes. Note at the bottom of
our bulletin that the average daily mid-latitude A index for the
past week was less than 1!

That same NOAA and Air Force prediction shows a low planetary A
index of only 5 for November 13-18, 8 on November 19-20, 6 on
November 21, and back to 5 again for November 22 and onward.
Geophysical Institute Prague for November 13-19 predicts quiet
November 13-14, quiet to unsettled November 15, and quiet again
November 16-19.

Bernie Mitchell, KD8KEO of Wayne, Michigan says he is a new amateur
radio operator (about 9 months) and had good luck on 40 meters with
the Nightwatch Net in the evening, but around the end of October
after 0000 UTC he noted signals seemed weak.

He didn't say where the other stations are, but running some numbers
through a propagation program -- such as W6ELprop -- shows quite a
seasonal variation between the end of October and two months
earlier, when using targets such as the center of the continental
United States, or Atlanta, for example.  But looking west, the
propagation is better on 40 meters.  Using California as a target,
about 2000 miles away, propagation seems to be good day and night in
August or October, whether we have sunspot activity or not.

Atlanta is only about 600 miles from Bernie, and 40 meters seems to
need a longer path at this time of year, and also note that signals
to the west have sunlight over the path much later in the day.

Willis Cooke, K5EWJ wrote in with a comment about backscatter.  He
writes, "I read with interest about the QSO between W5ZIT and AE5PW
on 10/30/09."

He continues, "On 11/02/09 I found HL3ERJ at 5x7 on 17 meters SSB at
2311 UTC. I gave him a quick call in the pile and received a prompt
answer with a 4x4 report. Many others across the western US were
calling but he could not hear them. W5/VK2ACM came on and announced
that he was in Louisiana and was the only other station to work Choi
(HL3ERJ) while I was listening. A California station asked Clint
(W5/VK2ACM) to QSY up and I followed. I found that Clint was 5x9
with my beam pointed toward Korea, but disappeared when I pointed it
at about 17 degrees toward Shreveport (where Clint was), 229 miles
to the North. After the California station finished, I called Clint
and we talked for about 5 minutes before he disappeared during one
of my short transmissions. An email to Clint confirmed that he had
not moved his beam from the NW and I had dropped out suddenly."

He goes on to say, "This is what I think is an E layer Ion Cloud
lying over the NW US and back scatter. W5ZIT with a fixed pattern
antenna would not be able to detect his path. We see this fairly
often on ten meters where it is often the only mode of propagation
available. It is also present on lower frequencies, but is sometimes
masked by F layer propagation so the only clues are shorter than
normal propagation to nearby stations. Actually, I think it is not
really short when the signal bounces off a cloud 1 or 2 thousand
miles away to return to Earth 1 or 2 hundred miles away. Usually
back scatter signals are not so strong, but sometimes they are."

Thanks, Willis!

Jon Jones, N0JK of Wichita, Kansas dropped a short line about 10
meters in the CQ Worldwide SSB DX Contest.  On Saturday afternoon,
October 24, HT2N in Nicaragua and several Brazilian stations were
very loud.  Using 10 watts on 10 meter SSB into a shortened
mag-mount CB whip on the roof of his car, he worked HT2N and PY5KD
around 2100 UTC while driving around and listening.

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 web page 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/.

Instructions for starting or ending email distribution of this
bulletin are at http://www.arrl.org/w1aw.html#email.

Sunspot numbers for November 5 through 11 were 15, 16, 11, 0, 14,
13, and 11 with a mean of 11.4.  10.7 cm flux was 70.5, 70.9, 70.6,
70.9, 72.1, 72.8, and 72.4 with a mean of 71.5.  Estimated planetary
A indices were 1, 0, 1, 6, 4, 1 and 1 with a mean of 2.  Estimated
mid-latitude A indices were 0, 0, 0, 4, 2, 0 and 0 with a mean of
0.86.
NNNN
/EX