ARRL

ARRL Propagation Bulletin ARLP049 (2012)

SB PROP @ ARL $ARLP049
ARLP049 Propagation de K7RA

ZCZC AP50
QST de W1AW  
Propagation Forecast Bulletin 49  ARLP049
From Tad Cook, K7RA
Seattle, WA  December 7, 2012
To all radio amateurs 

SB PROP ARL ARLP049
ARLP049 Propagation de K7RA

We had some trouble getting the solar flux values this week, but
found a work-around. We normally use
ftp://ftp.geolab.nrcan.gc.ca/data/solar_flux/daily_flux_values/fluxtable.txt
but it didn't seem to work yesterday. But another route was
discovered that does work,
http://www.spaceweather.ca/data-donnee/sol_flux/sx-5-flux-eng.php.

It has the same data. We could use the NOAA site at
http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt, but we like getting
the data with one more digit of resolution direct from the
observatory in British Columbia.

Solar activity declined again this week. Average daily sunspot
numbers dropped from 78.9 to 61.1, and average daily solar flux
declined from 121 to 101.6.

The latest prediction from NOAA/USAF is for solar flux at 95 on
December 7, 100 on December 8-9, 105 on December 10, 110 on December
11-12, 115 on December 13-14, 135 on December 15-17, then 130, 125
and 120 on December 18-20, 115 on December 21-23, 110 on December
24-27, 100 on December 28-29, 105 and 115 on December 30-31, 125 on
January 1-2, 130 on January 3-7, and 135 on January 8-13.

The predicted planetary A index is 8 on December 7-8, 5 on December
9, 8 on December 10, 5 on December 11-14, 8 on December 15, 5 on
December 16-28, 8 on December 29-30, 5 on December 31 through
January 1-6, then 10, 8 and 5 on January 7-9, and 8 on January
10-11.

The above forecast is from Thursday, December 6, and is revised from
the one issued a day earlier, which appeared in the ARRL Letter. The
latest forecast has lower solar flux over the next few days with
slightly more active geomagnetic conditions. We would like to see
better conditions than currently forecast for the ARRL 10 Meter
Contest this weekend.

Recently I mentioned a spreadsheet I made to track changes in the
45-day solar flux forecast from NOAA/USAF. I am going to try to
share the spreadsheet with you, and keep it updated online. To see
the spreadsheet, go to
https://sheet.zoho.com/public/tadcook/noaa-usaf-flux-prediction-archive-xls-1.

Unfortunately, I have not quite figured out how to freeze the column
headings across the top and the left column too, but you can look at
the spreadsheet, download it and play with it. Note that the last
entry is for December 6, 2012.

If you go down the left column to that date, then go to the right to
the December 6 column you will see the actual solar flux for that
date. As you go up the December 6 column, you see all the past solar
flux predictions for December 6, and see how they have varied over
time. As you go to the right from December 6, you see numbers
corresponding to the dates in each column, and those are the flux
values as predicted on December 6, from the predictions at
http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html.

Last year on the Friday-Saturday-Sunday of the ARRL 10 Meter Contest
weekend (December 9-11, 2011), the solar flux was 143.5, 140 and
134.3, and planetary A index was 1, 6 and 4. This year predicted for
the three days of December 7-9 is a solar flux of 95, 100 and 100,
and planetary A index of 8, 8 and 5. Note that the contest lasts
only two days, but we include the day before also, as activity on
that date should affect contest conditions. We prefer to see higher
solar flux and a lower A index.

There is also the possibility of enhanced propagation from ionized
meteor trails. The Geminid shower this year peaks on December 13,
but the Geminid activity runs from December 4-17, so we may see 10
meter propagation enhanced somewhat by the early part of the shower.

Check http://www.arrl.org/10-meter for details on the contest.

As usual, we received a geomagnetic forecast from OK1HH. He predicts
quiet conditions December 7, mostly quiet December 8, quiet to
active December 9, active to disturbed December 10-11, quiet
December 12, quiet to unsettled December 13-14, quiet December
15-16, quiet to active December 17, active to disturbed December 18,
mostly quiet December 19, quiet to active December 20-21, mostly
quiet December 22, quiet to unsettled December 23, quiet December
24-27, quiet to active December 28, and mostly quiet December 29-30.

Let's look at some moving averages for sunspot numbers. We have
tracked a three-month moving average for quite some time now. The
highest activity in this cycle was during the peak in fall 2011,
when the three months centered on October 2011 had an average daily
sunspot number of 118.8, and the November 2011 centered average was
118.6.

Now that November has ended, we know the three month moving average
for September 1 through November 30. The averages for this year
centered on January through October were 83.3, 73.7, 71.2, 87.3,
91.5, 96.5, 91.9, 89.9, 81.2 and 82.3. The monthly averages of daily
sunspot numbers for August through November were 85.8, 84, 73.8 and
89.3.

Another thing to look at is the yearly average of sunspot numbers,
and 2012 doesn't look bad. The average annual sunspot numbers for
2008 through 2011 were 4.7, 5.1, 25.5 and 29.9, and the average for
2012 to date (through December 6) was 83.8, quite a jump from last
year's 29.9. We got 83.8 by summing all the daily sunspot numbers
from January 1, 2012 through December 6, which was 28,581, and
divided that by the number of days, which is 341.

Ken Miller, K6CTW sends us the link to the Australian Government
Radio and Space Weather Services site at
http://www.ips.gov.au/HF_Systems. We've mentioned this site before,
but Ken points out some interesting features. Ken wrote, "One of
their features are HAP charts which are designed to indicate the
best frequency range, at that hour for communications between a
specified base and mobile within a nominated area.

"To access these, on the Left side menu bar, under Global HF, click
on HAP Charts.

"When the HAP Charts menu appears, click on Hourly HAP Charts, then
using the pull-down menu, select the center point nearest to your
station. When I'm home, I use Phoenix (even though I'm actually in
California). Then click on the Display button.

"The chart is very intuitive and the details of what it is
indicating are summarized below the chart.

"Lately, in the evenings, I have seen charts indicating RED which
show that the best communications for our traffic nets area would be
from 1-3 MHz. When that is indicated, signals have usually been very
degraded or even a total wash-out. The 'old school' saying is that
the band has gone 'long.'  These charts have been very accurate and
could benefit both NTS and DX operators alike."

Howard Lester, N7SO of Schuylerville, New York wrote on December 1,
"At 2145 UT today I worked RO9O in Asiatic Russia on 14.021 MHz CW.
He was a true 599 (with flutter - a polar path), and he gave me the
same (but of course, who knows, considering my 100 watts and dipole
antenna). Current conditions are Flux 102, K=2. The W6EL propagation
program, for those conditions, gives a prediction of 32 (signal
level) D, D being the '1 - 25% probability' category and with a
fairly low signal at that. The moral of the story is that it pays to
listen, or at least check http://www.dxwatch.com!"

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. Find more good
information and tutorials on propagation at
http://myplace.frontier.com/~k9la/.

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 November 29 through December 5 were 89, 67, 49,
43, 44, 58, and 78, with a mean of 61.1. 10.7 cm flux was 113.1,
110.6, 101.7, 97.7, 96.6, 96.2, and 95.5, with a mean of 101.6.
Estimated planetary A indices were 3, 2, 4, 7, 4, 3, and 2, with a
mean of 3.6. Estimated mid-latitude A indices were 2, 1, 3, 8, 3, 5
and 4, with a mean of 3.7.
NNNN
/EX