ARRL

ARRL Propagation Bulletin ARLP003 (2006)

SB PROP @ ARL $ARLP003
ARLP003 Propagation de K7RA

ZCZC AP03
QST de W1AW  
Propagation Forecast Bulletin 3  ARLP003
From Tad Cook, K7RA
Seattle, WA  January 20, 2006
To all radio amateurs 

SB PROP ARL ARLP003
ARLP003 Propagation de K7RA

As we cruise into the low part of solar cycle 23, the sun has been
very quiet, save for some coronal holes providing solar wind
streams. This week average daily sunspot numbers were up nearly ten
points compared to last. The geomagnetic field has been mostly
quiet, although a little more active than the previous week.

Over the next week expect solar flux to stay around 90, with
geomagnetic conditions quiet, except for some unsettled to active
conditions around January 23-24. Geophysical Institute Prague
expects quiet conditions January 21, quiet to unsettled January 20
and 22, unsettled January 25 and 26, unsettled to active January 23,
and active conditions (higher A and K index) on January 24.

Rich DiDonna, NN3W of Virginia writes that, "While conditions on the
high bands may stink, conditions on the low bands have been
spectacular. 40 meters is opening to Europe as early as 2100z from
the East Coast with reliable openings to the Middle East, and long
path to Southeast Asia. 80 and 160 have also been amazing. So, while
Old Sol may be in "nap" phase, one should not assume that there is a
lack of DX to work!"

Jon Jones, N0JK of Kansas echoes Rich's comments about the lower
frequencies in a January 14 email. He writes, "160 meter propagation
to Europe from the Midwest and western USA is picking up. For a low
band propagation beacon I listen to the 1.2 megawatt AM station from
Kvitsoy, Norway on 1314 kHz. Its signal has been very strong the
last couple of evenings. Great 160M conditions were noted by W8CAR
and others the same time to Europe."

Jon also noted an extensive 6 meter E layer opening on January 13-14
in which W1, W2, W3 and W4 stations were coming in.

Charles Lewis, S9SS of Sao Tome and Principe (an African island in
the Atlantic Ocean about 150 miles west of Libreville, Gabon) was
one of the stations reported in a recent bulletin by K7HP in Arizona
as worked on 10 meters. Charles writes, "The reason Hank worked me
that night is that I also use propagation beacons. On 10 meters, I
primarily depend on the W3VD beacon in Laurel, MD. That evening, as
I often do, I had the receiver tuned to the W3VD beacon while I
worked at the computer across the room. About 2110z I heard the
beacon rise dramatically out of the noise. I checked and found the
band was becoming live with 10 meters stations. I fired up my amp
and called CQ. In a period of about 40 minutes I worked about 40
stations. I would have worked many more, but it took a while of rag
chewing before I was discovered by the crowd."

He continues, "These late 10 meters openings are not very unusual
for me in the 2015 to 2130z time frame. They more often start around
2030 to 2040z. They might last a few minutes or they might last a
couple of hours. Until early last year, they were nearly nightly.
Now they are a lot more scarce. There have been many times that I
heard W3VD with a good signal and could raise no one or perhaps had
a long rag chew with someone followed by no takers afterward."

Charles goes on to say, "I also had a very good opening on 12/11,
the second day of the ARRL 10 Meters Contest that began about 2010z.
I worked about 115 contacts coast to coast in NA over a period of
about 50 minutes until it died. In that case also, I was working at
the computer and heard W3VD pop out of the noise. The band usually
dies about as suddenly as it comes to life."

He continues, "I am only about 20 miles north of the Equator. There
is only about a 20 minute variation in sunset time over the year.
The sun is usually down well before 1800z, so these openings are
long after my sunset".

Charles says that on 20 through 12 meters he uses the IARU beacon
system, and on 12 meters he often hears 4U1UN in NYC coming in
strong, while no one else seems to be on the band. He says 20 meters
is his best band for working the USA, and is the best way to
communicate with friends near his vacation home in Western North
Carolina.

Charles has an interesting challenge operating from his QTH, and
that is from a huge Voice of America transmitter site that seems to
hover over his station in a photo he sent. Check out a similar image
on the web at, http://groups.msn.com/s9ss.

A couple of weeks ago Carl Luetzelschwab, K9LA had some comments
about SSNe, or Effective Sunspot Numbers, and the T-Index. He
continues with more comments below, through the end of this
bulletin.

Carl begins, "In the January 6 Bulletin, I said the T Index and SSNe
were similar methods that give a better picture of what the
ionosphere is doing "now." Both represent an effective sunspot
number based on real-time sounding of the F2 region critical
frequency. Let's look at the basic difference between SSNe and the T
Index.

"SSNe is calculated from a worldwide set of ionosondes at
geomagnetic latitudes lower than 50 degrees. The SSNe plot also
shows the RMS % difference between the foF2 values used to derive
SSNe and foF2 calculated from the model using that SSNe as input.
This parameter typically runs about 20% or so - if it exceeds 30%
this indicates that the global ionosphere is departing more from the
model expectation than usual. And if it exceeds 50%, buyer beware!

"The T Index is calculated from 14 ionosondes in the Australian
sector. The regional maps (Australasia, Europe, and North America)
show the difference between the predicted monthly T Index (which is
in tabular format at www.ips.gov.au/HF_Systems/6/4/1) and the
current observed hourly conditions in the desired region.

"Which one is best to use? That's a tough call, but I'd personally
give the edge to SSNe for global predictions as it is based on
worldwide data.

"To reiterate from the January 6 Bulletin, neither gives us a daily
model of the ionosphere. But both do allow you to assess whether the
current conditions are generally equal to, better than, or worse
than the median value from your propagation prediction program when
using the heavily averaged smoothed sunspot number (or smoothed
solar flux).

"Thanks to Jim Secan of Northwest Research Associates in Tucson for
information on SSNe and for forwarding the T Index information from
Garth Patterson at IPS."

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 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. An archive of past
propagation bulletins is found at, http://www.arrl.org/w1aw/prop/.

Sunspot numbers for January 12 through 18 were 12, 0, 0, 32, 42, 36
and 50 with a mean of 24.6. 10.7 cm flux was 76.5, 76.5, 77.4, 80.9,
83.8, 82.5, and 85.6, with a mean of 80.5. Estimated planetary A
indices were 3, 2, 3, 4, 14, 8 and 5 with a mean of 5.6. Estimated
mid-latitude A indices were 2, 4, 2, 4, 8, 10 and 9, with a mean of
5.6.
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/EX