SB PROP @ ARL $ARLP043ARLP043 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 43 ARLP043
From Tad Cook, K7RA
Seattle, WA October 23, 2015
To all radio amateurs
SB PROP ARL ARLP043
ARLP043 Propagation de K7RA
Average daily sunspot numbers over the past week were up 38.1 pointsÂ to 75, and average daily solar flux rose 30.7 points to 118.2.
Geomagnetic conditions were quiet over the week, with averageÂ planetary A index declining from 25.1 to 11, and mid-latitude AÂ index dropping from 17.6 to 9.1.
Predicted solar flux is 125 on October 23-25, 120 on October 26-28,Â 115 on October 29-30, 85 on October 31 through November 1, 80 onÂ November 2-6, then 85, 90, 95, 100, 105, 110, 115 and 120 onÂ November 7-14, 125 on November 15-17, 120 on November 18-20, and 115Â on November 21-22. Flux values then drop to 80 on November 28through December 3.
Predicted planetary A index is 5, 12, 24 and 8 on October 23-26,Â then 5, 8, 12 and 10 on October 27-30, 5 on October 31 throughÂ November 2, 50 on November 3, 40 on November 4, 25 on November 5, 12Â on November 6-7, then 20, 25, 20 and 10 on November 8-11, and 8 onÂ November 12-13. A index then drops to 5 on November 19-24, thenÂ bounces back to 50 on November 30.
Those Ap index values of 50 on November 3 and again on November 30Â seem to be echoes of the October 7-8 period when planetary A indexÂ was 77 and 56. The high values are each spaced one whole solarÂ rotation (27-28 days) from each other.
F.K. Janda, OK1HH sent us his weekly prediction for geomagneticÂ conditions. He believes the geomagnetic field will be mostly quietÂ October 23, quiet to active October 24, quiet to unsettled OctoberÂ 25, quiet on October 26, mostly quiet October 27, quiet to activeÂ October 28, mostly quiet October 29, quiet to active October 30Â through November 1, active to disturbed November 2, quiet to activeÂ November 3, active to disturbed November 4, mostly quiet NovemberÂ 5-6, quiet to unsettled November 7, quiet to active November 8,Â active to disturbed November 9, quiet to active November 10, mostlyÂ quiet November 11-12, quiet to unsettled November 13-14, mostlyÂ quiet November 15, quiet to unsettled November 16, and quiet toÂ active November 17.
OK1HH expects increased solar wind on October 29-31, November 2-5,Â 10-11, 15, 18 and 19-20. The days October 29-30, November 2, 5,Â 10-11 and 19-20 have a lower probability of increased solar wind.
Now what do all these numbers mean? For good HF conditions we likeÂ to see a quiet geomagnetic field, and higher solar flux and sunspotÂ numbers. The A index also represents geomagnetic conditions, and forÂ this, single-digit numbers are desirable, the lower the better. An AÂ index about 10 represents unsettled to active conditions and when itÂ gets toward 50, this is a geomagnetic storm.
The main reason we like low geomagnetic numbers is the higherÂ numbers may indicate higher absorption.
for a good explanation of A index and other solar indices.
Dave Ballard, W2VK and David Moore both sent in a Science DailyÂ article about some large solar storms perhaps being undetected. ReadÂ it at http://bit.ly/1jDxjYh .
Ray Price, KE4YOG of Goldsboro, North Carolina wrote: “12 meters hasÂ been fun lately. I worked 9K2WA (Kuwait) on 21 October at 1518 UTCÂ along with several other stations. On 22 October at 2145 UTC IÂ worked V73D (Marshall Islands) for a ATNO (All Time New One) onÂ 24.955 MHz. I haven’t been able to be on but an hour or two here andÂ there, but 12 meters has been fun.Â “All were worked with a Kenwood TS480HX running 200 watts into a 230Â Doble up about 60 feet in the sycamore trees.”
The reference to the “230 Doble” had me scratching my head, but IÂ think he may be referring to a 230 foot long doublet. If so, that’sÂ a dipole about 6 wavelengths long on 12 meters.
Don’t forget, this weekend is the SSB portion of the CQ Worldwide DX
Contest. See http://www.cqww.com/rules.htm . Conditions should beÂ good, with no predicted geomagnetic storm until November 3.
If you would like to make a comment or have a tip for our readers,Â email the author at, firstname.lastname@example.org.
For more information concerning radio propagation, see the ARRLÂ Technical Information Service web page at,
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 andÂ 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 October 15 through 21 were 49, 68, 83, 81, 94,Â 77, and 73, with a mean of 75. 10.7 cm flux was 106.8, 109.1, 116.6,Â 119.5, 123.7, 122.8, and 129, with a mean of 118.2. EstimatedÂ planetary A indices were 10, 8, 11, 22, 5, 9, and 12, with a mean ofÂ 11. Estimated mid-latitude A indices were 9, 8, 9, 15, 3, 8, and 12,Â with a mean of 9.1.
I would like to thank K7RA for sending this update out every week and allowing me to post this on here for all my readers to read. If you haven’t done so already, please subscribe to my site so you will receive an email when I publish a new post. Also, please like me on Facebook and follow me on Twitter, Google+ and LinkedIn. Links to all my social media pages can be found under Social on the menu at the top of the page.
Until next time…
73 de Curtis, K5CLM