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ARRL Propagation Bulletin ARLP014 (2016)

ARLP014 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  April 1, 2016
To all radio amateurs 

ARLP014 Propagation de K7RA

Again this week solar indices crept lower. Average daily sunspot
numbers declined 8 points to 20.4, and average daily solar flux went
down 2.4 points to 86.4. Geomagnetic indices softened, with
planetary A index down 3 points to 8.9, and mid-latitude A index
down 1.2 points to 7.4.
Just one new sunspot appeared since March 17, and that was one week
later on March 24.
Predicted solar flux values from USAF and NOAA saw a major downward
shift on March 28.  Overnight, the predicted average daily solar
flux for the 38 days from April 4 through May 11 dropped from 91.6
to 82.2. You can see this by downloading the spreadsheet at .
Predicted solar flux is 82 on April 1, 81 on April 2-3, 80 on April
4-5, 75 on April 6, 80 on April 7-9, 85 on April 10-11, 80 on April
12-17, 85 on April 18-24, 80 on April 25-28, 85 on April 29 through
May 2, and 80 on May 3-6.
If the daily solar flux declines to 75 as predicted for April 6,
that will be the lowest flux value since the other side of this
solar cycle, when it was 74.8 on November 22, 2010.
Predicted planetary A index is 10, 26 and 18 on April 1-3, then 8,
18, and 14 on April 4-6, 10 on April 7-8, then 5, 15, 24, 22 and 20
on April 9-13, then 8 on April 14-15, and 5 on April 16-22, 12 on
April 23-24, 8 on April 25, then 5 on April 26-28, then 25 on April
29-30, 8 on May 1, and 5 on May 2-4. The A index then rises to 24,
22 and 20 on May 8-10.
From Petr Kolman, OK1MGW of the Czech Propagation Interest Group:
Geomagnetic activity forecast for the period April 1-27, 2016.
Geomagnetic field will be: 

Quiet on April 20-22 
Mostly quiet on April 1, 14, 17-19, 27 
Quiet to unsettled on April 5-6, 9, 10, 15-16, 25-26 
Quiet to active on April 4, 7-8, 13, 23-24 
Active to disturbed on April 2-3, 11-12
Increased solar wind from coronal holes are expected on April 1-4,
7-8, 10-13, and 23-24.
Do you like the new format for the above report? Whether you do, or
not, or don't care, register your opinion at
According to, "NOAA forecasters estimate a 45
percent chance of polar geomagnetic storms on April 1 when a CIR is
expected to hit Earth's magnetic field. CIRs (co- rotating
interaction regions) are transition zones between fast and
slow-moving solar wind streams. Density gradients and shock waves
inside CIRs often do a good job sparking auroras."
An interesting email exchange between Jon Jones, N0JK and Drew
Smith, K3PA.
N0JK wrote:
"I was on 10 meters fixed mobile this afternoon (March 27) playing
in the CQ WPX SSB on 10 meters. Saw this spot by KC0DEB:
ZM3T, March 27, 2026, 2113Z on 28420.0 WPX, KC0DEB
"Around 2050Z I was calling CU2ARA on 10 meters. When I let up on
the mic button I heard 'Japan Kilowatt.' Called again, let up and
heard the same. It sounded like my voice, but shifted down 500 Hz or
so, with a 5x5 strength and a hollow aurora sound.
I called several times to test it -- said my call one time, let up,
heard it every time. An echo??  Went down the band and called CN2AA
after working the CU2. Heard the same deal for a couple of calls,
even with just N0JK, then it was gone by 2100z. Had strong
back-scatter on US stations, WX3B was 57 on backscatter. "Japan
Kilowatt" is about 2 seconds. Speed of light = 300,000 km/second.
Earth circumference = 40,000 km. K index 3. Weird. Any ideas?
Suppose someone may have recorded my call and was playing it as DQRM
-- but their timing would have to be good to play it every time I
called, and on different spots on the band and only when the DX was
listening, not transmitting.
The distance for single hop F2 backscatter would be too short. I
recall K5CM tests for backscatter echoes on 6 and 10 meters. They
are a fraction of a second. 10 meters was very loud to the Caribbean
and West Africa, as well as New Zealand. I heard both sides of EC5AN
loud (Spain) work ZM4T (New Zealand) on 10 meters."
On March 28 N0JK commented: "I logged the VK0EK Cordell DXpedition
March 28 on 30 meter CW. They had just come up on 30 meters at 0250z
and worked them 'down 1 kHz.' My set up is 100 watts and load the
rain gutter on our home. Catching VK0EK in the clear and before the
pileup found them was a treat! 30 meters is an amazing band."
Further, he mentioned: "VK0EK has almost as many CW contacts on 80
as 40, note 40 also has SSB and digital QSOs. 30 meters is their
'money band.'
Over 1,000 contacts on 160 is encouraging.
Only 311 contacts on 10 meters is a concern. SFU today is 88. today notes 'the solar cycle is crashing."'
He also wrote (although I am not sure, he may have copied this from
some other source):
"For the past two years, the sunspot number has been dropping as the
sun transitions from Solar Max to Solar Min. Fewer sunspots means
there are fewer solar flares and coronal mass ejections (CMEs). As
the explosions subside, we deem the sun 'quiet.'
But how quiet is it, really? A widely-held misconception is that
space weather stalls and becomes uninteresting during periods of low
sunspot number. In fact, by turning the solar cycle sideways (see ), we
see that Solar Minimum brings many interesting changes. For
instance, the upper atmosphere of Earth collapses, allowing space
junk to accumulate around our planet. The heliosphere shrinks,
bringing interstellar space closer to Earth. And galactic cosmic
rays penetrate the inner solar system with relative ease."
How quiet is it? Let's take a look at our 3-month moving average of
sunspot numbers. The average for the three month period centered on
February 2016 (including all daily sunspot numbers from January 1
through March 31) was 49. This is the lowest number seen since
January 2011, when it was 35.3.
The moving average peaked in March, 2014 when it was 148.2. Since
May 2015 the averages were 77.7, 76.3, 69.1, 67.5, 64.5, 64.6, 58.5,
55.4, 53.5 and 49.
A nice image of lone sunspot 2526 is at . It was photographed by
astrophotographer Alexander Sorokin in his backyard at Azov, in
Rostov oblast in the Russian Federation.
David Moore sent this link to yet another article about superflares.
But this one speculates about bigger flares on distant stars, and
wonders if they could happen here in our solar system. I wouldn't
pay much attention to the speculation in comments at the end of this
piece, about our Earth being overdue for such an event. Seems to me
that claiming we are due for another one is the same logic as the
Gambler's Fallacy (see's_fallacy ).
Here is the article:
For more information concerning radio propagation, see the ARRL
Technical Information Service at For an explanation of the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are at
My own archives of the NOAA/USAF daily 45 day forecast for solar
flux and planetary A index are in downloadable spreadsheet format at and .
Click on "Download this file" to download the archive, and ignore
the security warning about file format. Pop-up blockers may suppress
the download.
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 24 through 30 were 25, 24, 23, 23, 23, 13,
and 12, with a mean of 28.4. 10.7 cm flux was 86.5, 85.5, 85.5,
88.2, 87.7, 87.8, and 83.8, with a mean of 88.8.  Estimated
planetary A indices were 7, 6, 3, 13, 10, 11, and 12, with a mean of
11.9. Estimated mid-latitude A indices were 7, 6, 2, 10, 9, 8, and
10, with a mean of 8.6.