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Propagation Forecast Bulletin #49 de K7RA:

from W1AW Bulletin via the ARRL on December 7, 2012
Website: http://www.arrl.org/
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Propagation Forecast Bulletin #49 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.

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

Source: W1AW Bulletin via the ARRL.

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