ARRL

ARRL Propagation Bulletin ARLP001 (2014)

SB PROP @ ARL $ARLP001
ARLP001 Propagation de K7RA

ZCZC AP01
QST de W1AW  
Propagation Forecast Bulletin 1  ARLP001
From Tad Cook, K7RA
Seattle, WA  January 3, 2014
To all radio amateurs 

SB PROP ARL ARLP001
ARLP001 Propagation de K7RA

Average daily sunspot numbers for the past week declined from 114.6
to 107.4, and average solar flux went from 138.8 to 139.2. This is
comparing the period from December 26 through January 1 with the
previous seven days.

The average daily sunspot number for the entire year of 2013 was
97.1, the highest since 2003. For 2008-2013 the yearly average was
4.7, 5.1, 25.5, 80.1, 82.3 and 97.1.

We've also been tracking a 3-month moving average of daily sunspot
numbers, and the value for October 1 through December 31 was 123.7,
the highest since December 2002 through February 2003, when it was
128.9.

The average daily sunspot number for October through December at
123.7 was even higher than the values for the first peak of the
current solar cycle in late 2011.  Back then the three month
averages ending in November and December were 118.8 and 118.6.

The average daily sunspot numbers for the three month periods ending
in February through December 2013 were 80.7, 85.2, 106.4, 106.4,
97.5, 85.6, 77.4, 91.2, 102.9 and 123.7. This is a moving average,
rather than a quarterly average. So each average includes another
new month as it drops off an old one.

Predicted solar flux for the short term is 165 on January 3, 170 on
January 4-5, then 175 and 170 on January 6-7, 165 on January 8-9,
then 135, 140 and 135 on January 10-12, 145 on January 13-14, 150 on
January 15-18, 145 on January 19, 140 on January 20-21 and 135 on
January 22-24.

Predicted planetary A index is 10 and 8 on January 3-4, then 5 on
January 5-22, then 10 and 8 on January 23-24.

OK1HH predicts active to disturbed geomagnetic conditions on January
3-4, quiet to unsettled January 5, quiet on January 6-9, quiet to
unsettled January 10, quiet to active January 11, quiet to unsettled
January 12, and mostly quiet on January 13-17.

Clark Stewart, W8TN of Hurricane, West Virginia pointed out that the
call ZM9ODX mentioned in the final propagation bulletin for 2013,
ARLP053, actually belongs to a New Zealand special event station. It
is not located on the subantarctic Auckland and Campbell islands, as
K6TTD thought. Ed Callaway, N4II of Boca Raton, Florida also pointed
this out.

W8TN has a nice blog devoted to amateur radio. Check it out at
http://w8tn.blogspot.com/ .

Randy Crews, W7TJ of Spokane, Washington sent in an observation on
the current solar cycle:

"The year 2013 will have the highest average Solar Flux of Cycle 24,
123 vs. 120 approximately for 2012. Fourth Quarter of 2011 was still
the highest quarter of Solar activity in Cycle 24 with an average SF
of 147.7 vs. 142.7 for the fourth quarter of 2013. It looks as if we
will see a carry over effect into the New Year.

"The big difference has been the SIZE of sunspots, not the number.
Comparatively, we have had the same number of sunspots each month of
this year. (Usually about 10-15 spots per day.) In October, November
and December there was a dramatic increase in the size of the
sunspots, raising the solar flux to values in the 160 to 175 range
and igniting 10 and 12 meters. Currently there is a very large
sunspot rotating into view on the left side of the Sun.

"Sunspots are important, however as this cycle has demonstrated -
size does matter. Twenty small sunspots can be present, however if
they are small, increases in solar flux will be anemic, and the
higher bands will suffer. The key is solar flux, and CERTAINLY NOT
the lagging indicator of smoothed sunspot numbers which will show a
peak long after it occurs. Kind of like showing up for the Rose Bowl
in Pasadena two months after it's played or put another way, you can
be running Europeans on 10 Meters with a SF of 175, and the Solar
Cycle peak might be 'officially' noted as happening three months
later when the Solar Flux is 95, and your sweating talking to
Europeans on 15 meters - hardly an accurate depiction and certainly
having no bearing on amateur's operating plans for either contests
or DXing."

NASA released an updated solar cycle prediction, which you can see
at http://solarscience.msfc.nasa.gov/predict.shtml. The difference
from last month is they have upped their estimate for smoothed
sunspot number at the maximum from 65 to 67. Also, last month they
said "The smoothed sunspot number has been flat over the last four
months. We are currently over four years into Cycle 24."

This month that same paragraph was changed to "The smoothed sunspot
number has been rising again towards a second peak over the last
three months. We are currently over five years into Cycle 24."

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service web page at
http://arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere. 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/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://arrl.org/propagation.

Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.

Sunspot numbers for December 26 through January 1 were 96, 107, 95,
119, 93, 136, and 106, with a mean of 107.4. 10.7 cm flux was 124.7,
130.6, 134.5, 137, 142.9, 145.3, and 159.6, with a mean of 139.2.
Estimated planetary A indices were 3, 3, 3, 5, 3, 6, and 12, with a
mean of 5. Estimated mid-latitude A indices were 2, 3, 4, 4, 2, 6,
and 11, with a mean of 4.6.
NNNN
/EX