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ARRL Propagation Bulletin ARLP010 (2020)

ARLP010 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 10  ARLP010
From Tad Cook, K7RA
Seattle, WA  March 6, 2020
To all radio amateurs 

ARLP010 Propagation de K7RA

Last week we pointed out in Propagation Forecast Bulletin ARLP009
that the NASA STEREO images (at )
showed two bright spots, magnetically complex, about to rotate over
the Sun's eastern horizon and onto the visible solar disc. I was
hoping these might develop into sunspots, but they both quickly
faded away, so currently we have seen no sunspots in 33 days.
Clearly, we are still at solar minimum.

These STEREO images are always in real time, constantly updated, so
they always show a live update of images.

Over the past week average daily solar flux shifted from 70.5 to 70,
average daily planetary A index stayed the same at 6.7, while
average daily mid-latitude A index shifted slightly from 5 to 4.6.

This period of low solar flux and very stable geomagnetic indicators
is great for 160 meter propagation, especially now during the winter
season, when we enjoy very low atmospheric noise.

On Thursday, reported a faint coronal mass ejection
detected by STEREO spacecraft on March 2. This is slow moving and
expected to hit Earth on March 7, and is probably why planetary A
index is predicted at 8 on March 7-8.

Predicted solar flux over the next 45 days is 70 on March 6-13 and
71 on March 14 through April 19.

Predicted planetary A index is 6 on March 6, 8 on March 7-8, 5 on
March 9-14, then 10, 8, 10 and 8 on March 15-18, then 5, 10, 8 and 5
on March 19-22, then 8, 12, and 10 on March 23-25, 5 on March 26-30,
then 20, 15 and 8 on March 31 to April 2, and 5 on April 3-19.

David Moore reports, "space weather model gives earlier warning of
satellite-killing radiation storms. Two-day notice lets satellite
operators take protective measures against energetic electrons:


"A new machine-learning computer model accurately predicts damaging
radiation storms caused by the Van Allen belts two days prior to the
storm, the most advanced notice to date, according to the new

This reports a new type of solar event, and how it might be used to
predict the onset of a new solar cycle:

N0JK comments:

"The VP8PJ DXpedition just went QRT about 0102z March 6. The group
did an outstanding job being 'available' for contacts despite
adverse conditions. They stayed an additional day - March 5. This
was fortuitous as VP8PJ enjoyed a great 15 Meter opening to North
America all afternoon.  This with a SFI of just 70 and the Kp index
of 1.

"As for propagation - from Kansas - VP8PJ was heard most frequently
on 40, 30, and 20 meters. They had a great, consistent signal on 30
meters. I am sure even low power stations with simple antennas on 30
meters were successful working VP8PJ. Here logged with about 50
watts and a 'rain gutter' antenna. Good signal on 40 meters but more
difficult to work. 20 meters was the best band to work them on SSB.

"17 meters and up were more challenging. On my fixed mobile, the 17
meter signal was very weak until March 1. Nil on 15 meters for me
until March 5.  Nothing on the higher bands. I noted spots by North
American stations for VP8PJ on 10 Meters March 1 and 3. VOACAP did
not predict any 10 Meter propagation to North America for VP8PJ to
the Midwest, even for an 'expert DXer.'"

The latest from Dr. Tamitha Skov, WX6SWW:

This weekend is the phone portion of the ARRL International DX
Contest. Check for details.

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 and the ARRL Technical Information
Service web page 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 February 27 through March 4, 2020 were 0, 0, 0,
0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 70.9, 70.6, 70.1,
69.3, 69.3, 70, and 69.8, with a mean of 70. Estimated planetary A
indices were 4, 6, 11, 8, 5, 6, and 7, with a mean of 6.7. Middle
latitude A index was 2, 4, 8, 6, 4, 4, and 4, with a mean of 4.6.


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