QST de W1AW
Propagation Forecast Bulletin 3Â ARLP003
From Tad Cook, K7RA
Seattle, WAÂ January 15, 2016
To all radio amateurs
SB PROP ARL ARLP003
ARLP003 Propagation de K7RA
Trends over the past week were just the way we like them, withÂ average daily sunspot numbers and solar flux increasing, andÂ geomagnetic indices lower, compared to the previous seven days.
Why do we like these numbers? When solar flux and sunspot numbersÂ are higher, this increases the likelihood that there will beÂ openings on HF. Lower geomagnetic indices suggest lower absorption.
Average daily sunspot numbers rose from 41 to 55.7, and averageÂ daily solar flux increased from 98.2 to 106.5. Average daily planetary A index declined from 16.6 to 11.1, while average dailyÂ mid-latitude A index went from 10.6 to 8.4.
These comparisons are for the January 7-13 period against theÂ previous seven days.
Predicted solar flux is 105 on January 15, 110 on January 16-18, 105Â on January 19-21, 100 on January 22, 105 on January 23-26, 110 onÂ January 27-28, 105 on January 29-31, 110 on February 1-7, then 108,Â 105 and 100 on February 8-10, 105 on February 11-14, 100 on FebruaryÂ 15-18 and 105 on February 19-22.
Predicted planetary A index is 5 on January 15-21, 15 on January 22,Â 10 on January 23, 5 on January 24-27, then 18, 12 and 8 on JanuaryÂ 28-30, 5 on January 31 through February 1, then 15, 12 and 8 onÂ February 2-4, 5 on February 5-6, then 6, 15, 12 and 8 on FebruaryÂ 7-10, 6 on February 11-13, 5 on February 14-16, 8 on February 17 andÂ 15 on February 18.
F.K. Janda, OK1HH of the Czech Propagation Interest Group predictsÂ quiet to unsettled geomagnetic conditions on January 15, quiet toÂ active January 16, quiet to unsettled January 17, mostly quietÂ January 18, quiet to active January 19-20, mostly quiet January 21,Â quiet to active January 22, mostly quiet January 23-24, quiet onÂ January 25, quiet to unsettled January 26, active to disturbedÂ January 27, quiet to active January 28, quiet on January 29-31,Â quiet to active on February 1-2, quiet to unsettled February 3,Â quiet on February 4-5, mostly quiet February 6-7, active toÂ disturbed February 8 and quiet to active February 9.
There are a couple of articles about propagation in the FebruaryÂ 2016 issue of QST. Check out “Radio Wave Propagation: How WavesÂ Attenuate With Distance” by Kai Siwiak, KE4PT on page 37, and “MakeÂ the Most of Ten Meters” by Steve Ford, WB8IMY on page 83.
Sorry, no reader reports this week.
Have you tried the online version of the VOACAP propagationÂ prediction program? It’s easy to use, and quite versatile. You canÂ drag the endpoints of any path around the map, and the polar displayÂ to the right of the map gives you the hour-by-hour outlook for eachÂ band. VOACAP uses the predicted smoothed sunspot number for theÂ month to make the predictions, and that number is alreadyÂ incorporated in the predictions here.
Check it out at http://www.voacap.com/prediction.html .
If you would like to make a comment or have a tip for our readers,Â email the author at k7ra @ arrl . net.
- For more information concerning radio propagation, see the ARRLÂ Technical Information Service web page at,Â http://arrl.org/propagation-of-rf-signals.
- For an explanation of theÂ numbers used in this bulletin, seeÂ http://arrl.org/the-sun-the-earth-the-ionosphere.
- An archive of pastÂ propagation bulletins is atÂ http://arrl.org/w1aw-bulletins-archive-propagation.
- More goodÂ information and tutorials on propagation are at http://k9la.us/.
My own archives of the NOAA/USAF daily 45 day forecast for solarÂ flux and planetary A index are in downloadable spreadsheet format atÂ http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .
Click on “Download this file” to download the archive, and ignoreÂ the security warning about file format. Pop-up blockers may suppressÂ the download.
Monthly propagation charts between four USA regions and twelveÂ overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRLÂ bulletins are at http://arrl.org/bulletins.
Sunspot numbers for January 7 through 13 were 57, 80, 84, 73, 41,Â 29, and 26, with a mean of 55.7. 10.7 cm flux was 103.4, 108.5, 107,Â 108.9, 108, 105.5, and 104.1, with a mean of 106.5. EstimatedÂ planetary A indices were 14, 8, 6, 7, 14, 15, and 14, with a mean ofÂ 11.1. Estimated mid-latitude A indices were 11, 6, 5, 7, 9, 10, andÂ 11, with a mean of 8.4.