SB PROP @ ARL $ARLP012   
   ARLP012 Propagation de K7RA   
      
   ZCZC AP12   
   QST de W1AW   
   Propagation Forecast Bulletin 12  ARLP012   
   > From Tad Cook, K7RA   
   Seattle, WA  March 18, 2016   
   To all radio amateurs   
      
   SB PROP ARL ARLP012   
   ARLP012 Propagation de K7RA   
      
   Solar indicators were lower this week, while geomagnetic indicators were   
   higher.   
      
   Compared to the previous seven days, average daily sunspot numbers in our   
   reporting week (March 10-16) were down 12.7 points to 51.7, and average daily   
   solar flux was down 3.2 points to 93.6. Average planetary A index was up 2.8   
   points to 15.7, and average mid-latitude A index increased from 8.6 to 12.   
      
   The latest forecast has a predicted solar flux of 95 on March 18-19, 90 on   
   March 20, 85 on March 21-24, 90 on March 25, 95 on March 26-28, 100 on March   
   29-31, 95 on April 1-9, 93 on April 10, 90 on April 11-15, 95 on April 16-17,   
   and 90 on April 18-19. Flux values then rise to 100 on April 25-27.   
      
   Predicted planetary A index is 16, 8, 6 and 5 on March 18-21, then 6, 8 and 10   
   on March 22-24, 5 on March 25-31, then 8, 30, 25 and 8 on April 1-4, and 5 on   
   April 5-6. Planetary A index rises to 25 on April 11 and 30 on April 29.   
      
   Petr Kolman, OK1MGW predicts geomagnetic conditions will be mostly quiet on   
   March 18-19, quiet on March 20-21, mostly quiet March 22, quiet to unsettled   
   March 23-24, quiet on March 25-26, quiet to   
   unsettled March 27, quiet to active March 28-29, quiet to unsettled March 30,   
   mostly quiet March 31 to April 1, active to disturbed April 2-3 (although the   
   forecast is uncertain for these two days), quiet to active April 4, quiet to   
   unsettled April 5-6, quiet to active April 7-8, mostly quiet April 9, active   
   to disturbed April 10-12 and quiet to unsettled on April 13.   
      
   Petr expects an increase on solar wind from coronal holes on March 23-24   
   (although like the April 2-3 forecast, this is uncertain) March 27-29, April   
   1-4, April 7-8, and April 10-12.   
      
   Tomas Hood, NW7US asked that this message be posted in the current propagation   
   bulletin:   
      
   "Tad, would you share this?   
      
   "Tomas, NW7US, has posted a new, breathtakingly beautiful video of our Sun, at   
   https://www.youtube.com/watch?v=HgP0e1VHBxc .  This high-definition video   
   shows the Sun in the 171-angstrom wavelength of extreme ultraviolet light. It   
   covers a time period of January 2, 2015 to January 28, 2016 at a cadence of   
   one frame every hour, or 24 frames per day. This time-lapse is repeated with   
   narration by solar scientist Nicholeen Viall and contains close-ups and   
   annotations.   
      
   "The Sun is always changing and NASA's Solar Dynamics Observatory is always   
   watching. Launched on Feb. 11, 2010, SDO keeps a 24-hour eye on the entire   
   disk of the Sun, with a prime view of the graceful dance of solar material   
   coursing through the Sun's atmosphere, the corona. SDO's sixth year in orbit   
   was no exception.   
      
   "SDO's Atmospheric Imaging Assembly (AIA) captures a shot of the Sun every 12   
   seconds in 10 different wavelengths. The images shown here are based on a   
   wavelength of 171 angstroms, which is in the extreme ultraviolet range and   
   shows solar material at around 600,000 Kelvin (about 1 million degrees F). In   
   this wavelength it is easy to see the Sun's 25-day rotation.   
      
   "During the course of the video, the Sun subtly increases and decreases in   
   apparent size. This is because the distance between the SDO spacecraft and the   
   Sun varies over time. The image is, however, remarkably consistent and stable   
   despite the fact that SDO orbits Earth at 6,876 miles per hour and the Earth   
   orbits the Sun at 67,062 miles per hour.   
      
   "Scientists study these images to better understand the complex    
   lectromagnetic system causing the constant movement on the Sun, which can   
   ultimately have an effect closer to Earth, too: Flares and another type of   
   solar explosion called coronal mass ejections can sometimes disrupt technology   
   in space. Moreover, studying our closest star is one way of learning about   
   other stars in the galaxy. NASA's Goddard Space Flight Center in Greenbelt,   
   Maryland built, operates, and manages the SDO spacecraft for NASA's Science   
   Mission Directorate in Washington, D.C."   
      
   Jim Wilson, K5ND of Grapevine, Texas wrote on March 15:   
      
   "Just thought I'd mention a very fun tropo opening this morning between Texas   
   and the Southeast. It was my first experience with this and I wrote about it   
   at, http://www.k5nd.net/2016/03/tropospheric-ducting-march-2016/ ."   
      
   Thanks, Jim.   
      
   This weekend the Vernal Equinox occurs at 0430 UTC on Sunday, March 20. Now   
   there is more energy from the Sun impacting the ionosphere in the Northern   
   Hemisphere, and this should enhance HF propagation.   
      
   Toward the end of last week's propagation forecast bulletin, htt   
   ://www.arrl.org/w1aw-bulletins-archive/ARLP011/2016 , we posted a question   
   from Steve Shorey, G3ZPS and a reference to a K9LA resource. K9LA responded   
   this week: "My article doesn't say much about what actually happens in the   
   atmosphere when the K index spikes up - it just shows that the ionization can   
   be enhanced, and we have a model that could help show what's happening   
   real-time.   
      
   "What happens is the energy from geomagnetic activity results in waves   
   propagating through the atmosphere, and that rearranges the major F2 region   
   players - atomic oxygen for electron production and molecular nitrogen/oxygen   
   for electron depletion."   
      
   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 10 through 16 were 61, 48, 56, 43, 57, 44, and 53,   
   with a mean of 51.7. 10.7 cm flux was 95, 94.2, 95, 92.6, 93.4, 94.1, and 91,   
   with a mean of 93.6. Estimated planetary A indices were 10, 23, 13, 4, 14, 24,   
   and 22, with a mean of 15.7. Estimated mid-latitude A indices were 7, 21, 11,   
   4, 11, 17, and 13, with a mean of 12.   
      
   NNNN   
   /EX   
      
   )\/(ark   
      
   Always Mount a Scratch Monkey   
      
   ... There's no Betty Rubble in Flintstones Chewable Vitamins.   
   ---   
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