ARRL

ARRL Propagation Bulletin ARLP046 (2004)

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 12, 2004
To all radio amateurs 

SB PROP ARL ARLP046
ARLP046 Propagation de K7RA

This was a wild week for propagation, fraught with radio blackouts,
6-meter auroral propagation, wild solar wind and severe geomagnetic
storms.

Looking at the numbers summarized at the end of each bulletin, this
week's average daily planetary A index (indicating geomagnetic
instability) was up by nearly 70 points to 77.6, and the
mid-latitude A index increased over 36 points to 41.9. Average daily
sunspot numbers and solar flux declined. Our reporting week, for the
convenience of putting out this report prior to each weekend, runs
from each Thursday through the following Wednesday.

The prediction for the next few days is for continuing aurora
displays and geomagnetic storms, but the storms should subside. The
predicted planetary A index for today, November 12, is 100, followed
by 30 on Saturday and 10 on Sunday. Today's possible geomagnetic
storm is predicted because of a coronal mass ejection blown into
space on November 10. But this blast is not aimed at earth, so the
effect is not as strong as it would be if the event were squarely in
the middle of the solar disk.

Predicted solar flux, which averaged under 130 this week, is
expected to decline over the next few days and then rise again, with
predicted flux values of 90, 85, 85, 90, 100 and 105 for November
12-17. Solar flux and associated sunspot numbers for the short term
are expected to peak some time around November 23-24.

A good web site to look at to see the rise of geomagnetic numbers
over several latitudes is at,
http://www.sec.noaa.gov/ftpdir/indices/DGD.txt. This shows the
previous month, so if you're looking at this in the future (perhaps
on the archive on the http://www.arrl.org/w1aw/prop/ web site),
you'll only see the current conditions, not what we're seeing today.

The numbers are quite dramatic, especially if you have a feel for
the A index and K index that you hear on the hourly WWV broadcasts,
and how they relate to what you are hearing on the air.

Lots of mail came in concerning geomagnetic storms, which
accompanied unstable and often unusable conditions on the HF bands,
but produced interesting propagation and excitement on VHF. Jon
Jones, N0JK, paraphrasing last week's bulletin, wrote that "The VHF
Community *is not* hoping 'it is more moderate than the current
prediction.'"

Chip Margelli, K7JA wrote an interesting note concerning HF
conditions at the end of the CW Sweepstakes followed by all the
excitement on 6-meters. He said that some signals on 15-meters had a
distinct aurora flutter, but others were completely flutter-free and
quite loud. About 50 percent of the stations to the east of him (he
is in Southern California) had an auroral characteristic.

I'll let Chip tell the rest: "About 0545z November 8th (late Sunday
night in California), KH6SX reported on the 50 MHz Propagation
Logger that he was hearing the K6FV beacon on 6-meters. I quickly
rotated my beam in his direction, and with one call I had him in the
log. His signal was full of rapid aurora flutter, which is
astounding for a path to Hawaii!"

He goes on to say, "The opening then moved westward, with W6YM,
WA6KLK, KG6I, and others in the Northern California working him. It
progressed to the Northwest, where N7EPD, KE7V, K7SS, and
undoubtedly more logged him. Then further west to KL7FZ in BP51!
And then JA2DDN and a host of other JAs were worked by KH6SX!"

Chip adds, "From here in Southern California, the signal
characteristics suggest some odd auroral-E to AU link. It's hard to
imagine a "normal" E opening with such a wide distribution, and the
westward progression suggests an enhancement ahead of the
heliopause. But I think the book may need some re-writing on this
one, and the exact mechanics are a bit of a mystery to me. I bet an
inspection of the solar wind velocity plots after 0500z would make
interesting reading."

He continues, "No easterly propagation was observed, to my
knowledge, from Southern California prior to the KH6 event. If this
really was an aurora event worked from Hawaii, this may be a
"first," and KH6SX is to be congratulated for being so on the ball!"

The 50 MHz Propagation Logger web page that Chip mentioned is at,
http://www.dxworld.com/50prop.html.

K7SS here in Seattle related moments of sheer joy on 6-meters. It
was reported that in Connecticut, Dennis Motschenbacher, K7BV,
bagged his fiftieth state on 50 MHz when he worked Kevin Forster,
NL7Z in Wasilla, Alaska via aurora.

Junji Saito, JA7SSB wrote that he was on 20 and 30 meters on
November 8 around 1430-1500z (late evening in Japan) when the bands
are usually closed for him, but he generated a big pileup of
European stations. He noticed that the signals had deep fading and
echoes.

Carl Zelich, AA4MI sent in a useful link to a glossary of
solar-terrestrial terms. It is on the NOAA Space Environment Center
web site at http://www.sec.noaa.gov/info/glossary.html.

If you would like to comment or have a tip, email the author at,
k7ra@arrl.net.

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at,
http://www.arrl.org/tis/info/propagation.html.

Sunspot numbers for November 4 through 10 were 135, 83, 106, 94, 93,
90 and 50 with a mean of 93. 10.7 cm flux was 136, 141.2, 128.8,
129.6, 124.1, 140.9 and 104.6, with a mean of 129.3. Estimated
planetary A indices were 7, 4, 3, 39, 189, 120 and 181, with a mean
of 77.6. Estimated mid-latitude A indices were 5, 1, 4, 19, 116, 47
and 101, with a mean of 41.9.
NNNN
/EX