Source: ARRL News
Date: March 11, 2016
SB PROP @ ARL $ARLP011
ARLP011 Propagation de K7RA
QST de W1AW
Propagation Forecast Bulletin 11Â ARLP011
From Tad Cook, K7RA
Seattle, WAÂ March 11, 2016
To all radio amateurs
SB PROP ARL ARLP011
ARLP011 Propagation de K7RA
Average daily sunspot numbers and solar flux both increased over theÂ past week. Average daily solar flux went from 92.9 to 96.8, and theÂ average daily sunspot number from 41.4 to 64.4. Geomagnetic
indicators increased, with the most activity on March 6 and 7.
On March 6-7 the planetary A index was 35 and 24.Â According to Spaceweather.com this was caused by a CIR. On March 4 they wrote,Â “NOAA forecasters estimate a 50% chance of polar geomagnetic storms
on March 6th when a co-rotating interaction region (CIR) is expectedÂ to hit Earth’s magnetic field. CIRs are transition zones betweenÂ fast and slow-moving solar wind streams. Solar wind plasma piles up
in these regions, producing density gradients and shock waves thatÂ do a good job of sparking auroras.”
Spaceweather.com also mentioned that the Spring Equinox (Sunday,Â March 20 at 0430 UTC) is a time for enhanced aurora activity. TheÂ weeks around equinoxes (both Autumnal and Vernal) are a time of
increased aurora borealis. 6 meter operators will want to be alert.
On March 6 Spaceweather.com reported a G-2 Class geomagnetic storm.Â (Go to http://www.swpc.noaa.gov/noaa-scales-explanation and click onÂ the Geomagnetic Storms tab for details). G-2 signals a moderateÂ geomagnetic storm, and typically “HF radio propagation can fade at
higher latitudes, and aurora has been seen as low as New York andÂ Idaho.”
Predicted solar flux is 95 on March 11-13, 90 on March 14-17, 95 onÂ March 18-20, 90 on March 21-23, and 95 on March 24-30. Solar fluxÂ then continues to meander between 90 and 95 for the remained of theÂ 45 day forecast.
Predicted planetary A index is 5 and 10, on March 11-12, 8 on MarchÂ 13-14, 5 on March 15, 30 and 24 on March 16-17, 25 on March 18-19,Â 12 on March 20, then 5 on March 21 through April 2, then 22, 10 and
8 on April 3-5 and 5 on April 6-7. The planetary A index thenÂ increases to 25 again on April 13-15.
F.K. Janda, OK1HH expects geomagnetic conditions to be quiet toÂ unsettled March 11-12, quiet to active March 13, active to disturbedÂ on March 14-16 (although the March 15-16 period is less likely),Â quiet to active March 17, mostly quiet March 18-19, quiet on MarchÂ 20-21, mostly quiet March 22, quiet again on March 23, mostly quietÂ March 24, quiet in March 25-27, quiet to active March 28, quiet toÂ unsettled March 29-30, mostly quiet March 31, quiet on April 1-2,Â active to disturbed April 3-4, quiet to active April 5 and mostlyÂ quiet April 6.
OK1HH expects increases in solar wind on March 14-17 and again onÂ March 30 to April 4, but the outlook for increased solar wind isÂ less certain for March 30-31.
On March 8, Dr. Jon Jones, N0JK (editor, The World Above 50 MHz inÂ QST) of Lawrence, Kansas wrote:
“Did not expect a lot on 10 meters Sunday morning of the ARRL DX SSBÂ contest with solar flux around 100. But conditions were remarkableÂ in eastern Kansas.
“Starting at 1707z with EI4KF, worked scads of Europeans. ManyÂ eastern Europeans were loud, along with Africa. The best DX wasÂ FH/IK5ZUI and ES5Q. 5D3A and HB9AUS were 20 over S9. I was ‘fixed
mobile’ on a hill top just west of Lawrence, antenna a 1/4 wave whipÂ for 10 meters with a MFJ tri-magnet mount on the roof of the car.”
KC0DEB, also in Kansas noted, “It was pretty neat to see howÂ propagation moved on 10 meters, from North Africa through CentralÂ and Eastern Europe to the Baltics and back down again to Southern
France and Spain. Not all signals were strong, but the majority wereÂ Q5. 9A1A (Croatia) was one of the loudest ones I heard here from EUÂ on 10m though. I think it was Paul N4PN behind the mic, pegging the
S-meter at 9+40dB! Unbelievable!
“Around 1800z I noted aurora polar flutter on SK3W and ES5Q andÂ considerable QSB on many Europeans. HB9AUS was solid and very loud.Â There was a geomagnetic storm in progress at this time, with the KpÂ peaking at 7.”
On March 10, Jeff Hartley, N8II of Shepherdstown, West VirginiaÂ wrote:
“Well today was a great example of conditions falling well short ofÂ the solar indices. All day long, the MUF on northern hemisphereÂ paths were low especially into EU and polar paths/northern EU were
almost closed. I heard nothing on 10M except for South America.Â There were ‘no storms’ present or forecast all day from WWV and theÂ solar flux was pretty steady at 95 down from 97 Wednesday. Other
stations I worked agreed that conditions were poor as well. 15Â meters seemed completely closed to EU at 1815Z vs. 10 meters openÂ well at same time Sunday.
“I was not very active in the ARRL DX SSB contest last weekend onÂ March 5 and 6, visiting Luray Caverns nearby with a friend onÂ Saturday; it really is quite a natural wonder.
“Friday evening sounded very good on all bands 15M working my wayÂ down to 75M by 0245Z and QRT around 0320Z. JAs had good signals onÂ 15M at the start with one booming Alaskan, Hawaiians and SouthÂ Americans, then 20 was pretty well open to all of EU except RussiaÂ with very loud signals from even the northern Caribbean down intoÂ SA. Some zone 18/19 Asiatic Russians and Alaska were loud as well.Â 40 was wide open to EU at 0130Z and the United Arab Emirates wereÂ worked. EU signals were good on 75, but precip static crashes wereÂ fairly high.
“Sunday was an excellent example of wonderful conditions that wereÂ actually enhanced by an impending G3 level storm.Â At 1513Z, IÂ finally returned to the radio to find 10 meters open well to EU,Â working two Swedish stations in about the first 8 QSOs. I had a niceÂ run of EU callers for about a half hour until signals weakened fromÂ most of the continent except Ireland, Italy, and the Balkans.Â MostÂ signals were quite good strength including calls from Lithuania,Â Latvia, Norway, Finland, Poland, Macedonia, and Kaliningrad.
“Following my run conditions turned quite strange on 10M with veryÂ weak Spanish, German, and French stations obviously getting veryÂ loud signals from the Midwest from OH to CO and even some W6/7s!
“Irish and some Brits/Welsh were still quite loud in the 1600Z hour.Â The K index was 5 by 1800Z and 6 before the end of the contest.Â Around 1730Z, conditions on 10 improved with loud signals from
Norway, Sweden, Finland, and Latvia as well as French and Italians.Â A St. Petersburg station called me at 1811Z for first Russian of theÂ day. Most signals from northern EU did NOT have flutter, but some
from SW EU did!
“After a break, returning at 1950Z signals were loud from Spain andÂ Portugal well into their evening and signals from even as close asÂ Cuba were loud from the south with only moderate signals fromÂ Brazil/Argentina due to the high MUF to the south. Sunday was quiteÂ a celebration of 10 meters, a last gasp probably until the next cycle. 15 was excellent to all of EU as well.”
Thanks Jeff for your report.
We haven’t heard from Martin McCormick, WB5AGZ in Stillwater,Â Oklahoma in a very long time. But he contributed this on March 7:
“10 meters still has a bit of life left in it but the vital signsÂ are becoming less frequent.
“I have taken to leaving an FM receiver on 29.6 MHZ and recordingÂ its output to catch anything interesting from a discone antenna upÂ about 50 feet.
“It does occasionally spring to life for very brief periods butÂ nothing like it was during past solar cycles or even in the WinterÂ of 2014.
“I live in almost the exact center of the contiguous United StatesÂ and Winter F2 usually brings us the extreme northeast down to aboutÂ New Jersey plus the extreme Northwest from roughly Canada to CentralÂ California. One also hears the extreme Southeast, mostly Florida andÂ the Caribbean plus far southwest as in Hawaii and the South Pacific.
“If the F2 really gets going, the skip zone gets a bit larger and weÂ start hearing further inland all around but this F2 season has beenÂ pretty spartan.
“The last two weeks have been a pretty good example, mostly deadÂ except for some openings on the low end of 10 meters and a couple ofÂ surprises.
“On Friday February 19, I began hearing a station in the first callÂ district calling CQ on 29.6 between 0900 and 1000 or so (local,Â 1500-1600 UTC) with fades from nothing to almost full quieting and
then it all died away.
“On Sunday March 6, I had forgotten the receiver was even on andÂ then about 1600 Central time, I heard a brief burst of carrier whichÂ I first thought was a local station until there was another burst of
carrier which was on long enough to fade a bit.
“I next heard an unidentified station which faded in and then outÂ with what sounded like possibly an Australian accent but I never gotÂ the call sign.
“Other partial QSOs were audible but not well enough to haveÂ participated and then the pipeline opened up for listening withÂ KH6RC on the big island of Hawaii talking to a station in SantaÂ Rosa, California which I could never hear from here.
“The Hawaiian station ranged from almost full quieting to a closedÂ squelch but was what I would call a good copy.
“A few minutes later, it all vanished around 1700 Central time,Â which is UTC-6 (2300 UTC). This is pretty typical of 10 meters whenÂ conditions are marginal.
“F2 is only going to generally get worse as the solar activityÂ declines but in two more months, the Northern Hemisphere will be inÂ Summer sporadic-E season and that can open up at any time of the day
or night with lots of skip in the 400-800 mile range and coverÂ frequencies from 10 meters through 6 and sometimes even 2 meters andÂ 222-225 MHZ.
“They don’t call it sporadic-E for nothing. The VHF bands can be asÂ dead as a doornail one minute and then booming with signals theÂ next. Of course the next minute after that it may be back to dead
again so one must strike while the iron is hot!”
Here we go again with another scary story on the infamous and trulyÂ frightening nineteenth century Carrington Event, this time fromÂ regular contributor David Moore.
NOAA says (on March 11, 2016) that there is a less than 1% chance ofÂ solar flares today. There are sunspots all over the Earth-facingÂ solar image, but with solar activity remaining low, there seems to
be little chance of any aurora or geomagnetic activity.
Steve Shorey wrote:
“Steve G3ZPS here near London UK
“I’m sure all those on the air noticed that HF conditions improvedÂ spectacularly over the weekend of 5th and 6th March – FoF2 over 9MHzÂ in Europe and 10m open to West Coast US from UK. I’m sure the
contesters were happy!
“The Sunday improvement was just before the arrival of the predictedÂ Geomagnetic storm that triggered a G2 class storm and visibleÂ auroras. I have noticed on more than occasion in the last year that
HF (and sometimes up to 6 meters) propagation improves markedly justÂ before the storms arrive.
“Of course the immediate aftermath is poor conditions for a few daysÂ (FoF2 way down on Monday). Is there any known correlation betweenÂ the sudden uptick in HF conditions just prior to a geomagnetic
disturbance – e.g. is the F2 intensely ionized by some mechanismÂ just a few hours before?
“Regards from UKÂ Steve G3ZPS”
I suspect what was happening is outlined in this piece by K9LA:
The STORM model he references has moved to:
I will Cc K9LA and see what he thinks.
If you would like to make a comment or have a tip for our readers,Â email the author at email@example.com.
For more information concerning radio propagation, see
- the ARRLÂ Technical Information Service web page at,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 March 3 through 9 were 50, 95, 68, 68, 61, 48,Â and 61, with a mean of 64.4. 10.7 cm flux was 98.7, 100.5, 96.2,Â 95.5, 94.1, 95.5, and 97.4, with a mean of 96.8. Estimated planetary
A indices were 8, 4, 4, 35, 24, 8, and 7, with a mean of 12.9.Â Estimated mid-latitude A indices were 7, 2, 3, 19, 17, 6, and 6,Â with a mean of 8.6.
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