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ARRL Propagation Bulletin ARLP011 (2018)

ARLP011 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 11  ARLP011
From Tad Cook, K7RA
Seattle, WA  March 16, 2018
To all radio amateurs 

ARLP011 Propagation de K7RA

No sunspots were observed between March 2 and March 15.  One sunspot
made a brief appearance on March 2, after a blank sun on March 1.
Average daily sunspot number dropped from 1.6 to zero this week, and
average daily solar flux rose fractionally from 67.6 to 67.7.  We'll
be watching the latest sunspot appearance to see if it is as
fleeting as the March 2 sunspot.

Geomagnetic indicators rose slightly, with planetary A index
increasing from 5.1 to 7.1, and mid-latitude A index rose from 4.6
to 5.7.

Predicted solar flux is 69 on March 16 to 23, 72 on March 24 to 29,
70 on March 30, 68 on March 31 through April 11, 70 on April 12, 72
on April 13 to 25, 70 on April 26, and 68 on April 27 to 29.

Predicted planetary A index is 15 on March 16 to 18, 10 on March 19,
5 on March 20 to 22, then 8, 5, 8 and 20 on March 23 to 26, 5 on
March 27 to 29, 8 on March 30 and 31, 5 on April 1 to 9, then 8, 10,
14, 16 and 20 on April 10 to 14, 5 on April 15 and 16, then 12, 18,
10, 5, 8 and 20 on April 17 to 22, then 5 on April 23 to 25, 8 on
April 26 and 27, and 5 on April 28 and 29.

Carl Luetzelshwab, K9LA has a comment about solar flux and an
observation from N0JK in last week's bulletin ARLP010:

"Jon Jones, N0JK said Sometimes the solar flux numbers don't
correlate well to the actual ionization.

What Jon said is more the norm than the exception, as solar
radiation is not the only factor that contributes to the amount of
ionization at any given location.  There are two other factors.  One
is geomagnetic field activity (the K index), which can modify the
amount of ionization.  The other is an event in the lower atmosphere
that couples up to the ionosphere, which also can modify the amount
of ionization and which is a very hot topic with researchers

The bottom line is if today's solar flux is higher than yesterday's,
it does not necessarily mean that the ionosphere is better today -
it could be worse.  The result of all of this is that we have
monthly median propagation predictions (they are statistical over a
month's time frame), not daily propagation predictions."

This in from Tamitha Skov on early Thursday in a message titled
"Solarstorm Mania all over the news":

"How ironic is it that only one week after I talk about significant
advances towards making Space Weather a household name, we get
smacked in the face with a bogus story about a massive solar storm
threatening to swallow the Earth?  From what I've heard, this story
began innocently enough-- someone misread an info-graphic on a
Russian space weather website.  But then the mistake went viral.
Over the past few days, reports spread around the globe, sending
people into a panic.  I've watched major news agencies publish the
story, only to print embarrassing retractions a day later.  All of
this simply because they ran with a story they did not have the
expertise to fact check.  I hate to admit it, but just as I thought
we were doing so well, I am reminded of how far we have yet to go.

"This week our Sun is indeed sending us a solar storm, but it's not
all fire and brimstone.  It's the weak, wispy kind we continue to
expect as we approach solar minimum.  The fact that the storm is
weak actually brings us some good news.  For amateur radio operators
and emergency communicators already wrestling with poor radio
propagation conditions on Earth's day side, communications might
improve on Earth's night side, especially with auroral propagation.
GPS users should also enjoy the quiet conditions, but be aware for
glitches, especially after sunset and at higher latitudes where
aurora is active.  As for aurora sightings during this weak storm,
reports are coming in from Norway, Sweden, and Finland as well as
from Ontario, Manitoba, and Saskatchewan Canada.  In the U.S.A.
aurora has been sighted as far south as Michigan and Minnesota.

"While all of these solar storm effects are surely noteworthy, they
are hardly catastrophic or even massive.  So as far as all the hype?
I think we can safely put that story to bed."

"Geomagnetic activity forecast for the period March 16 to Apr 10,
2018 from F.K. Janda, OK1HH.

Geomagnetic field will be:
Quiet on March 20, 24, 28 and 29, April 1 and 2, 4 to 9
Mostly quiet on March 21, 30 and 31, April 3
Quiet to unsettled on March 19, 22 and 23, 25, 27
Quiet to active on March 16 to 18
Active to disturbed on March 26

Solar wind will intensify on March 16 to 18, (19 and 20, 25 and 26,
April 3 to -?).

- Parenthesis means lower probability of activity enhancement."

This is from Jeff, N8II from West Virginia on March 15:

"There probably are a record number of Dxpeditions to the 'Terrible
T's' and other countries from Africa, so named because several of
the African countries that begin with T (former French) were some of
the rarest countries.

Today on 15 meters TN5R, Congo Republic, TY7C, Benin, and TJ2TT,
Cameroon were all operating 15M phone at the same time as were the
returning Lithuanians on Annobon Island, 3C0W.  I worked Annobon,
failed to get Cameroon, and had already worked the other two.  In
addition on 15M phone were 5V7SM, Togo (worked) and 9X9PS from
Rwanda, quite a line up.

At times, signals from Africa have been totally unreadable or very
weak on 15M, but the solar wind picked up today raising the MUF
despite nearly identical SFI (69 today) compared to other days this

Also, an expedition to PJ5 was unreadable on 15M CW the past 2 days,
was S9 at 1400Z today.  The best signals for the most part from
Africa were in the 1400Z hour also, except for Annobon who was
louder around 1600Z.  I have logged the Benin and Congo groups on
several bands including 80M, but the MUF has been too low to hear
any of them on 12 or 10 meters.  The only rare DX worked this week
on 12M was XR0YD, Easter Is. on CW who has also been logged on 80
through 15M.

Conditions on 80 are considerably worse than in Dec. and Jan., but
good enough to still work some of the Dxpeditions.  160M signals
have been very weak, but 40 and 30 meters have improved as the night
time MUF has risen due to seasonal change.  I finally logged Annobon
on 30M today after quite a bit of calling during which they were
good copy to loud but running many Japanese and EU stations.  I
would guess their 30M JA/USA QSO ratio was at least 25 to 1 up until
today when they were S9 at 2000Z (my sunset is 2318Z), louder than
yesterday.  So, obviously they had a very good JA path for several
hours, way before JA sunrise until way after their sunrise.

20 meters continues to be my best band for DX by far; I also logged
A5A in Bhutan around 1500Z on CW today. EU signals are generally
moderate to fairly loud all morning long and SW EU stays in to about
2200Z on good days. The morning short path to Australia appears to
be closed to very marginal most days. 17 meters is often usable to
Europe and the Middle East around 1400-1700Z, but signals are weaker
and often exclude northern and eastern EU."

Mark Lunday, WD4ELG in Greensboro, North Carolina has sent some
interesting reports on his experiments with QRSS mode. What is it?
Extremely slow speed CW, so slow that a single dit may last for 60
seconds. Using a computer sound card and special QRSS software,
stations running power levels as low as 10 microwatts can be
extracted out of the noise.


For more information concerning radio propagation, see the ARRL
Technical Information Service at  For an explanation of
numbers used in this bulletin, see

An archive of past propagation bulletins is at  More good
information and tutorials on propagation are 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 8 through 14, 2018 were 0, 0, 0, 0, 0, 0,
and 0, with a mean of 0.  10.7 cm flux was 66.6, 67.5, 67.7, 67.8,
68.1, 68.6, and 67.7, with a mean of 67.7.  Estimated planetary A
indices were 4, 12, 12, 6, 3, 4, and 9, with a mean of 7.1.
Estimated mid-latitude A indices were 3, 10, 9, 7, 2, 3, and 6, with
a mean of 5.7.


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