ARRL

ARRL Propagation Bulletin ARLP012 (2012)

SB PROP @ ARL $ARLP012
ARLP012 Propagation de K7RA

ZCZC AP12
QST de W1AW  
Propagation Forecast Bulletin 12  ARLP012
From Tad Cook, K7RA
Seattle, WA  March 23, 2012
To all radio amateurs 

SB PROP ARL ARLP012
ARLP012 Propagation de K7RA

Solar activity declined this week.  Average daily sunspot numbers
were off by over 13 points to 75.1, and average daily solar flux
dropped over 32 points to 102.1.

Solar flux dropped barely below 100, but rounded up to 100 as shown
on the NOAA SEC site at,
http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt.

The next short-term peak in solar flux is expected at the 135 level
for April 3-6.  Predicted solar flux for March 23-25 is 100, 105 on
March 26, 110 on March 27, 115 on March 28-29, 120 on March 30, and
130 on March 31 through April 2, then 135 on April 3-6, and 130,
120, 115 and 105 on April 7-10, 100 on April 11-15, 105 and 110 on
April 16-17, and 100 on April 18-22.

Predicted planetary A index is 5 on March 23-27, 10 on March 28, 8
on March 29-31, 5 on April 1-2, 8 on April 3-4, 5 on April 5-9, then
12, 5, 5, 15 and 10 on April 10-14, and 5 again on April 15-23, then
10 on April 24, 8 on April 25-27, and 5 on April 28-29.

The CQ World Wide SSB WPX Contest should see good conditions this
weekend.

Even with the decline, new sunspot groups were popping out this
week.  On Thursday, March 15 sunspot group 1435 appeared, and the
next day 1436 emerged, followed by 1437 on March 17. On March 18,
1437 disappeared, followed by 1436 on March 19, and on March 20 two
new groups, 1438 and 1439 appeared. On March 21, 1439 disappeared
while 1440 emerged. On March 22, three new sunspot groups, 1441,
1442 and 1443 appeared.

Fred Glenn, K9SO of Palatine, Illinois sent in an interesting
article about neutrino communications.  You can read about it here:
http://www.v3.co.uk/v3-uk/v3-co-uk-labs-blog/2161410/scientists-digital-neutrino-beam-transmit-practically.
Of course, with a 0.1 Hz data rate - would a dit take 10 seconds to
transmit? - and a 170 ton detector, this medium requires a little
work.

Howard Lester, N7SO pointed out that the link we gave in last week's
Propagation Forecast Bulletin ARLP011 to Alan Friedman's images show
photos taken in Buffalo, not Brooklyn.  Also, I had a real "doh!"
slap-my-forehead moment when he pointed out that pictures of the Sun
are not affected by light pollution from city streetlights and other
urban sources that bedevil astronomers searching the night sky.

In a message titled "Propagation Weirdness," Jim Hadlock, K7WA of
Seattle, Washington on March 22 wrote, "This morning while chasing
EU stations on 17 meter CW I worked 9M6YBG (at 1614Z on 18080) - and
it wasn't the first time.  Last year on March 30 I worked him at
1627Z, about midnight his time. I guess it's 'anything can happen
day!'"

I thought that might be unusual if Jim was beaming Europe, as the
short path antenna heading from Seattle to Europe is about 30
degrees. Short path toward East Malaysia is about 300 degrees and
long path about 120 degrees.  But then it occurred to me that Jim
may not have been using a highly directional antenna.

Doing some crude propagation modeling with W6ELprop, the time that
Jim contacted 9M6YBG is actually the beginning of a second opening
for the day on 17 meters at this time of year in early spring. The
model shows a brief opening from 0600-0730 UTC (11:00 PM Pacific
Daylight Time until 12:30 AM) but the second opening looks better,
after 1600 UTC, very strong and reliable through 1930 UTC.

Yet another article about our Sun popped up the other day, and I
like the way it describes our Sun's corona as "covered and bound up
with strong magnetic fields that are ropy and twisted in nature,"
like "a writhing mass of snakes holding in the surface of a globe."
See it for yourself at,
http://news.thomasnet.com/green_clean/2012/03/20/anticipating-a-temper-tantrum-from-the-sun-in-2013/.

A story out of Fargo, North Dakota describes a doctoral candidate's
effort to accurately predict sunspot activity. See the article at,
http://www.grandforksherald.com/event/article/id/232610/ and the
photo at,
http://www.grandforksherald.com/event/image/id/58086/headline/Cherish%20Bauer-Reich/.

On March 17, Jeff Hartley, N8II of Shepherdstown, West Virginia
wrote: "It seemed like disturbed conditions most of the week. The
SFI really took a nose dive today compared to 2-3 days ago, only 100
with K index currently 2. 15 meters was almost dead to EU in the
1400Z hour which is usually about the best hour, just a few rather
weak Mediterranean area stations. The Russians on 20 were 'watery,'
fluttery especially from Asia, but did log a few UA9 area stations
mostly from zone 17. Even the Moscow area stations were weak unless
beaming toward USA."

Finally, check out a couple of interesting links from
http://www.spacewx.com/Space_Weather_Now.html.  Click on "Solar" and
then the "Terrestrial" links. They show some interesting indicators
for geomagnetic activity and solar flux.

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://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. Find more good
information and tutorials on propagation at
http://myplace.frontier.com/~k9la/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.

Sunspot numbers for March 15 through 21 were 85, 104, 89, 54, 58,
74, and 62, with a mean of 75.1. 10.7 cm flux was 110.6, 98.5,
102.4, 102, 101.8, 99.6, and 99.9, with a mean of 102.1. Estimated
planetary A indices were 30, 20, 20, 10, 10, 4, and 4, with a mean
of 14. Estimated mid-latitude A indices were 24, 17, 15, 11, 8, 4,
and 4, with a mean of 11.9.
NNNN
/EX