ARRL

ARRL Propagation Bulletin ARLP009 (2009)

SB PROP @ ARL $ARLP009
ARLP009 Propagation de K7RA

ZCZC AP09
QST de W1AW  
Propagation Forecast Bulletin 9  ARLP009
From Tad Cook, K7RA
Seattle, WA  February 27, 2009
To all radio amateurs 

SB PROP ARL ARLP009
ARLP009 Propagation de K7RA

Excitement mounted a few days ago when new Cycle-24 sunspot 1013
emerged, but two days later it was fading away, similar to other
recent sunspot appearances.  The sunspot number for February 24-26
was 12, 14 and 12.  Today's number will likely be 0.

In a few weeks is the Vernal Equinox -- the first day of Spring in
the Northern Hemisphere -- on March 20, 2009 at 1144z.  Areas north
and south of the equator will be bathed in an equal amount of Sun,
and this is always a good time for HF propagation.

Using one of the popular propagation programs to predict a path from
California to Australia using an average sunspot number of 12, on 15
meters on January 20, there was a good chance of an opening from
2130-0100z, with an excellent chance within that period, at
2330-0030z.  On March 20 using the same numbers, the chances of
propagation look excellent from 2200-0230z, with the band perhaps
opening at 2130z and shutting down at 0330z.  This gives us an
illustration of propagation changing with the season.

Another example would be Dallas to Brazil.  On January 20 on 20
meters the band would probably be open from 1800-2300z, with signals
gradually increasing about 12 dB over that period.  On March 20 a
likely 20 meter opening would be from 1830-0230z, with signals
increasing 16 dB over that period, and rising faster as well.

Geomagnetic activity has been very quiet for a long time now, and
this is expected to continue.  NOAA and the U.S. Air Force predict a
planetary A index of 5 over the next two weeks, with minor
exceptions.  On March 3 the A index may rise to 8.  Geophysical
Institute Prague predicts quiet conditions February 28 through March
2, quiet to unsettled March 3-4, then back to quiet on March 5.

The predicted quiet conditions should be good for the CQ 160-Meter
SSB DX Contest this weekend.

Mike Schaffer, KA4JAW lives in West Central Florida, and enjoys
observing sporadic-E propagation on broadcast television.  His local
Channel 2 station, WEDU, ceased analog transmissions recently,
eliminating co-channel interference with Channel 3.  On Sunday,
February 22 just after 2300z Mike noticed a wrestling match on
Channel 3, and shortly after a logo appeared for TGV, a broadcaster
in Guatemala City (see http://www.canal3.com.gt/).  The station is
over 1,000 miles away.

Joaquin Montoya, EA2CCG in Spain reported good conditions over the
past few days during the brief sunspot appearance.  On February 25,
2100-2130z he worked a number of states in the Western United States
including one in Montana while he was mobile on 20 meters.  He could
hear K5D, and earlier that day he worked K5D on 17 meters and 6V7P
in Senegal as well.

An Alaskan newspaper this week ran a story about subdued aurora due
to low solar activity.  See it at,
http://www.adn.com/news/alaska/interior/story/700194.html and note
their confusing comment about the Sun having an 11 year positive
cycle following an 11 year negative cycle.  Perhaps they refer to
the switch in magnetic polarity in individual sunspots.

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 February 19 through 25 were 0, 0, 0, 0, 0, 12,
and 14 with a mean of 3.7.  10.7 cm flux was 68.9, 69.2, 70.6, 70.3,
70.8, 71, and 70.7 with a mean of 70.2.  Estimated planetary A
indices were 1, 3, 3, 3, 5, 6 and 3 with a mean of 3.4.  Estimated
mid-latitude A indices were 0, 3, 2, 3, 3, 6 and 2 with a mean of
2.7.
NNNN
/EX