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ARRL Propagation Bulletin ARLP013 (2012)

ARLP013 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 13  ARLP013
From Tad Cook, K7RA
Seattle, WA  March 30, 2012
To all radio amateurs 

ARLP013 Propagation de K7RA

Eight new sunspot groups appeared this week, but the average daily
sunspot number declined four points to 71.1. Average daily solar
flux rose by less than two points to 103.7.

On Thursday, March 22 three new sunspot groups appeared, numbered
1441, 1442 and 1443. Two more groups appeared on Friday - 1444 and
1445 - and 1442 vanished from view. On March 24 group 1441
disappeared, and on March 25 new group 1446 emerged. On March 26,
groups 1440, 1443 and 1446 faded away, but 1442 - not seen since
four days earlier - re-emerged. On March 27 group 1444 disappeared
and 1447 appeared, and on March 28 new group 1448 arrived.

For the short term, planetary A index is predicted to be 5 on March
30 through April 9, then 12 on April 10, and back to 5 on April
11-12, then 15 and 10 on April 13-14, followed by 5 on April 15-23.
A similar pattern appears way out in May, when planetary A index is
predicted at 12 on May 7, then 15 again on May 10. It's a good guess
that this is probably based on the rotation of the Sun relative to
Earth, predicting that an active magnetic area could appear again
27-28 days later.

The solar flux prediction shows flux values of 120, 130 and 135 on
March 30 through April 1, then 140 on April 2-6. On April 7-11 the
predicted solar flux is 130, 125, 120, 110 and 105. On April 12-15
the predicted solar flux is 100. It then goes to 105 and 110 on
April 16-17, and back to 100 on April 18-21, then 105 on April
22-23, 110 on April 24-25, 120, 125, and 130 on April 26-28, and 135
on April 29-30.  Another peak at 140 is predicted for May 1-3.

"Q-up Now" has a fascinating new set of real-time propagation tools
at, developed by a team associated with the
Utah State University Space Weather Center
( in Logan, Utah.

They use a real-time model of the ionosphere called GAIM (Global
Assimilation of Ionospheric Measurements) which is updated every 15
minutes with 10,000 global TEC (Total Electron Content) measurements
to simulate the F layers.  Then they use the ABBYNormal Model (see to model the D and E
layers, and the two models are combined to give a complete
representation of the global ionosphere.

On the first page you will see NVIS maps for Near Vertical Incidence
Skywave propagation.  These are not quite ready yet, and currently
the maps shown are several days old.

Most interesting is the HF Availability
( area in which you can model
real-time propagation for the frequency of your choice between any
two points and beyond out to the antipodes.  You can use
latitude/longitude coordinates, but I found it easiest to just copy
grid square data from callsign servers such as

This tool also works on 160 meters, which the propagation prediction
programs that many of us use do not. Of course the major difference
with this tool is that it tells you what the propagation should be
over any path right now, but they are planning on offering a
predictive tool.

Have fun!

Torsten Schwarz, XE2/K5TOR wrote:

"On Sunday 03/25/2012 at 9:00 local time (1500 UTC) I was surprised
that I was hearing a US FM Radio station on my radio (103.1 MHz) as
clean as if it were a local station. At that time I was driving from
my home QTH (Saltillo, MX grid DL95ml) to work and all that time the
signal was very strong. I also managed to transmit an APRS Packet
with no problem (Saltillo has no IGate or digi) you can look it up
on (Call: K5TOR-9). I have no idea what
propagation that was as it was at least 30min and there was hardly
any fading."

Using the site I searched for stations on
103.1 MHz in Texas.  A likely candidate was KPAS FM, and the
distance to Torsten's grid square from the transmitter site was 530
miles.  Perhaps some solid E layer skip was helping it along that

Pete Heins, N6ZE of Thousand Oaks, California wrote: "After various
parts of the US experienced long haul 6 meter DX to South America
and the Pacific on Wednesday and Thursday, 28/29 March 2012, I
worked FK8CP at 0342 UTC, on 29 March on CW: 51N/41N. I did not ID
any other DX stations, but heard a few other SoCal stations make a
few contacts. My rig is 100 watts with a 5 element Yagi up only 14

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at Find more good
information and tutorials on propagation at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for March 22 through 28 were 86, 74, 65, 84, 56, 63,
and 70, with a mean of 71.1. 10.7 cm flux was 102.4, 104.8, 102.7,
101.3, 102.4, 105.6, and 107, with a mean of 103.7. Estimated
planetary A indices were 6, 6, 10, 4, 4, 12, and 12, with a mean of
7.7. Estimated mid-latitude A indices were 6, 5, 9, 4, 4, 15, and
10, with a mean of 7.6.


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