SB PROP @ ARL $ARLP011
ARLP011 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 11 ARLP011
From Tad Cook, K7RA
Seattle, WA March 18, 2022
To all radio amateurs
SB PROP ARL ARLP011
ARLP011 Propagation de K7RA
We saw plenty of sunspot activity this week, along with numerous
A confounding indicator was a higher average solar flux but lower
average sunspot numbers. We expect to see them track together, but
that isn't always the case.
Average daily sunspot number went from 87.4 last week to 74.6 in the
latest reporting period, March 10-16.
Average daily solar flux increased from 115.5 to 119.
A new sunspot group appeared on March 12, another on March 13, and
two more on March 14. Total sunspot area (in millionths of the solar
disc) declined through the week, starting at 1170 on March 10, then
1080, 1040, 940, 670, 490 and 290. So, the decline continued even
through days that revealed new sunspots.
March 13 was the day with the greatest geomagnetic disturbance with
middle latitude A index at 30, planetary A index at 40, and Alaska's
college A index at 65. The A index is calculated from the K index,
updated every 3 hours. In Alaska, the K was 0 in the first three
readings, at 0000, 0300 and 0600 UTC, then jumped dramatically to 5,
7, 7, and 5 for the rest of the day. K index is logarithmic, and 7
is a very big number, indicating a geomagnetic storm.
The solar flux prediction peaks at 125 on April 6-8 but starting
today the predicted flux is 108 on March 18-19, 95 on March 20-26,
100 on March 27-28, 110 on March 29-30, 115 on March 31, then 120,
115 and 120 on April 1-3, 115 on April 4-5, 125 on April 6-8, 120 on
April 9-11, 115 on April 12-14, 110 on April 15-17, 100 on April 18,
then 95 on April 19-22 and 100 on April 23-24.
Predicted planetary A index is 10 on March 18-19, then 15, 12 and 8
on March 20-22, 5 on March 23-25, 10 and 8 on March 26-27, 5 on
March 28-30, then 10, 25, 15 and 8 on March 31 through April 3, 5 on
April 4-15, 12 on April 16-17, 8 on April 18, then 5 on April 19-21,
then 10 and 8 on April 22-23.
The Vernal Equinox will occur at 1533 UTC on Sunday, March 20, a
good sign for HF propagation as we move from Winter to Spring
conditions in the Northern Hemisphere.
From F.K. Janda, OK1HH:
"Undoubtedly, the most dramatic phenomenon of the last seven days
was the arrival of a CME on March 13, which broke away from the Sun
on March 10-11. It caused a medium (G2) geomagnetic storm. In its
positive phase, when MUF values increased during the UTC afternoon
until evening, while the overall ionospheric propagation of
decameter waves improved overall. In the following negative phase on
March 14-15, they deteriorated significantly. A return to normal has
been observed since March 16.
"A CME could do more than just ignite the bright Aurora Borealis. It
also lowered the level of cosmic rays. A Neutron monitor at the
Sodankyla Geophysical Observatory in Oulu, Finland, saw a sharp
decline in cosmic rays shortly after the CME arrived: It's called
the 'Forbush Decline' named after the American physicist Scott
Forbush, who studied cosmic rays in the early 20th century. It
happens when a cloud of coronal matter pushes galactic cosmic rays
away from our planet. The cosmic rays fell sharply on March 13, then
rose sharply at noon on March 14, then fell sharply again (we
attribute this fluctuation to the more complex structure of the CME
cloud). The cosmic rays remained depressed for 2 (partly to 4) days
after the arrival of the CME.
"The consequences of the coming of a CME in the Earth's
magnetosphere and ionosphere were now, near the Vernal Equinox, more
pronounced than they would have been at any other time of year."
I (K7RA) was experimenting with FT8 and PSKreporter.info on Friday,
March 11 on 10 meters and noticed at 2145 UTC my low power signal
with a very modest antenna was heard over a narrow arc running from
Northern Virginia and central Texas, plus reports from two stations
in New Zealand and several in South America. 15 minutes later the
only report was from K1HTV in Virginia. By 2224 UTC the only reports
were from two local Western Washington stations, at 4 and 54 miles
On March 15 using the same setup on 10 meters at 1651 UTC the only
station outside the local area hearing me was XE1ACA, 2,344 miles
Often when coverage is marginal on 10 meters, 12 meters will be
At 1730 UTC on 12 meters, I was heard over a broad arc of stations
1800-2400 miles away running from New Hampshire to South Texas, plus
XE2BCS and XE1GK at 1757 and 2003 miles and NH6Y in Hawaii at 2654
miles. That arc of coverage was only 600 miles wide.
On March 14, VE1VDM reported unstable 10 meter conditions. "As of
1600 UTC (1:00 PM local) today I have not had one RBN report on
28.173 MHz or one WSPR report on 28.126.130 MHz.
"The band has really tanked here in Nova Scotia."
N0JK reported on March 13:
"N0LL (EM09) decoded a number of South American stations on 50.313
MHz FT8 around 0040 UTC March 13. This included CE3SX (FF46),
CE0YHF/CE3, CE2SV and LU5FF. Larry was away from the radio when this
occurred. Suspect an Es link to TEP. He then worked XE2TT (DL44) on
Es at 0117 UTC. I monitored during this time frame. No South America
but did decode K3VN (EL98) around 0050 UTC on Es."
Also from Jon on the same day:
"A rare March sporadic-E opening on 6 meters the afternoon of the
11th from Kansas to W1, W2, W3 and W8.
"Here in Lawrence, I worked K3ISH FN21 and KE8FD EN80 on 50.313 MHz
FT8 around 2100 UT. Copied a few others.
"WQ0P (EM19) was in a better spot for it, He worked W1, W2, W3, W4
"No rare DX, but any sporadic-E opening in March is noteworthy. The
month of March has the lowest occurrence of sporadic-E of any month
of the year.
"See: https://www.qsl.net/pjdyer/ .
"If the Es cloud had been located to the southeast, a potential
link-up with afternoon TEP was possible. Did not see anyone working
A tribute to Astronomers Walter and Annie Maunder:
David Moore sent this about another astronomer:
The latest report from Dr. Tamitha Skov, WX6SWW, Space Weather
If you would like to make a comment or have a tip for our readers,
please email the author at, firstname.lastname@example.org.
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals. For
an explanation of numbers used in this bulletin, see
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at http://k9la.us/ .
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
Sunspot numbers for March 10 through 16, 2022 were 90, 81, 93, 64,
82, 71, and 41, with a mean of 74.6. 10.7 cm flux was 127.1, 126.5,
124.7, 122.9, 114.9, 110.4, and 106.6, with a mean of 119. Estimated
planetary A indices were 10, 20, 13, 40, 14, 7, and 5, with a mean
of 15.6. Middle latitude A index was 7, 15, 7, 30, 13, 5, and 3,
with a mean of 11.4.