SB PROP @ ARL $ARLP013   
   ARLP013 Propagation de K7RA   
      
   ZCZC AP13   
   QST de W1AW   
   Propagation Forecast Bulletin 13  ARLP013   
   > From Tad Cook, K7RA   
   Seattle, WA  March 28, 2016   
   To all radio amateurs   
      
   SB PROP ARL ARLP013   
   ARLP013 Propagation de K7RA   
      
   All of the indicators we track were lower over the past week (March 17-23),   
   compared to the previous seven days. Average daily sunspot numbers declined   
   from 51.7 to 28.4, and average daily solar flux was 88.8, compared to 98.6   
   during the prior seven days. Planetary A index was lower by 3.8 points to   
   11.9, and average mid-latitude A index (measured in Wallops Island, Virginia)   
   was down from 12 to 8.6. Lower geomagnetic indices are generally considered a   
   good thing for HF propagation.   
      
   Looking at the record at ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt we can   
   see that until March 24, there were no new sunspot regions since March 17 when   
   there was one, which followed two on the day before.   
      
   Even though our Sun is quiet, there is a seasonal variation which produces   
   aurora around the Vernal and Autumnal Equinox. (Vernal, or Spring Equinox was   
   on Sunday, March 20, 2016 and the next Autumnal or Fall Equinox this year will   
   occur on Thursday, September 22, 2016.)   
      
   Spaceweather.com supplied this article a few days ago explaining how this   
   works:   
      
   http://www-ssc.igpp.ucla.edu/personnel/russell/papers/40/ .   
      
   > From NOAA and the USAF, predicted solar flux is 88, 90, 92 and 88 on   
   > March 25-28, 90 on March 29 through April 3, 95 on April 4-11, 90 on   
   > April 12-17 and 85 on April 18-20. Flux values are predicted to go back   
   > to 95 again after April 30.   
      
   Also via NOAA, planetary A index for March 25-29 is predicted at 5, 8, 8, 10   
   and 8, then 5 on March 30 through April 1, then 30, 20 and 8 on April 2-4, 5   
   on April 5-7, then 10, 5, 15, 24, 22, and 20 on April 8-13, and 8 on April   
   14-15. The A index then jumps to 30 on April 29.   
      
   F.K. Janda, OK1HH sends us his geomagnetic forecast, but this week I want to   
   test a different format. You can see the format we've been using in past   
   bulletins at http://arrl.org/w1aw-bulletins-archive-propagation. See below for   
   a link to my survey.   
      
   Here is the proposed format:   
      
   Geomagnetic activity forecast for the period March 25-April 20, 2016   
      
   Geomagnetic field will be:   
   Quiet on March 25-26, April 1, 14, 17-18   
   Mostly quiet on March 30-31, April 6, 10, 15-16, 19   
   Quiet to unsettled on March 27, 29, April 7, 20   
   Quiet to active on March 28, April 5, 8-9, 11, 13   
   Active to disturbed on April 2-4, 12   
      
   Increases in solar wind are expected on March (30), April 4-6, 9, 11, 14   
      
   Remarks: - Parenthesis means lower probability of activity enhancement.   
      
   See examples and vote at, https://www.surveymonkey.com/r/BP9FMTZ .   
      
   Ray Soifer, W2RS in Green Valley, Arizona on March 24 sent this info about   
   working 30 meter grayline propagation yesterday morning:   
      
   "Interesting propagation. I heard nothing from VK0EK until half an hour before   
   sunrise. He peaked 579 around sunrise, then faded and was gone 30-40 minutes   
   after. Quite a grayline."   
      
   Ray didn't tell me that VK0EK is on Heard Island, but maybe I should already   
   know that:   
      
   http://vk0ek.org/   
      
   The distance from Ray's QTH to Heard Island is 10,945 miles, short path.   
      
   More info about Heard Island, from the Australian government:   
      
   http://heardisland.antarctica.gov.au/   
      
   Max White, M0VNG, and earlier David Moore sent this link to an ultraviolet   
   image of our Sun: http://bit.ly/1RqC0Ar .   
      
   Martin McCormick, WB5AGZ of Stillwater, Oklahoma sent this piece in a message   
   titled "Is it F2, or E?"   
      
   "One of the first things a person notices when listening to HF signals coming   
   from afar is a characteristic sound as if someone was continuously playing   
   with tone controls. It is especially noticeable on AM signals and the wider   
   the receiver passband, the more pronounced is the effect. This is known as   
   selective fading because different frequencies fade in and out at different   
   times.   
      
   "The Earth's ionosphere is a shell or several shells of electrically-charged   
   air molecules and atoms ranging from around 38 miles above us to about 310   
   miles high. The Sun and cosmic rays cause the molecules and atoms to loose   
   electrons which gives them a positive charge. They can reflect radio signals   
   and give us world-wide radio communication.   
      
   "The reflecting layers are the E layer at about 56-93 miles plus the F layer   
   complex which consists of several shells or layers that come, go and move   
   around based on Solar and Geo magnetic activity.   
      
   "The f2 layer is mostly responsible for short wave communications and the   
   selective fading is due to more than one layer reflecting the same signal back   
   to Earth. If the layers happen to be half of a wavelength apart, one receives   
   two versions of the same signal in which one version is delayed enough to   
   cause the carrier of an AM or FM signal to be cancelled out. Mother Nature   
   just turned a normal AM signal in to a double-sideband suppressed carrier   
   transmission.   
      
   "FM signals are also altered. It is possible to receive FM on an AM receiver   
   by tuning slightly off from center. It is called slope detection and has   
   existed for as long as there has been FM. If you tune right on to the   
   frequency, the audio is faint and muffled. F2 propagation, however, can cause   
   a selective fade just below or above the carrier frequency such that if you   
   are on the center frequency, the amplitude of the signal matches the deviation   
   and you can hear fairly good audio as if the signal was both AM and FM. Nature   
   automatically did that, also but the effect may not last more than a fraction   
   of a second.   
      
   "When sporadic-E is involved, signals still fade up and down but the E layer   
   acts like a single thin film and there is no selective fading. Except for   
   fades, signals sound local."   
      
   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 htt   
   ://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past propagation   
   bulletins is at http://arrl.org/w1aw-bulletins-archive-propagation. More good   
   information and tutorials on propagation are at http://k9la.us/.   
      
   My own archives of the NOAA/USAF daily 45 day forecast for solar flux and   
   planetary A index are in downloadable spreadsheet format at http   
   //bit.ly/1VOqf9B and http://bit.ly/1DcpaC5 .   
      
   Click on "Download this file" to download the archive, and ignore the security   
   warning about file format. Pop-up blockers may suppress the download.   
      
   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 March 17 through 23 were 66, 29, 26, 26, 25, 13, and 14,   
   with a mean of 28.4. 10.7 cm flux was 91.6, 90.3, 89.4, 87.6, 88.9, 87.3, and   
   86.8, with a mean of 88.8. Estimated planetary A indices were 21, 8, 18, 10,   
   8, 8, and 10, with a mean of 11.9. Estimated mid-latitude A indices were 16,   
   6, 12, 6, 7, 6, and 7, with a mean of 8.6.   
      
   NNNN   
   /EX   
      
   )\/(ark   
      
   Always Mount a Scratch Monkey   
      
   ... The real world is no place for artists.   
   ---   
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