SB PROP @ ARL $ARLP036   
   ARLP036 Propagation de K7RA   
      
   ZCZC AP36   
   QST de W1AW     
   Propagation Forecast Bulletin 36  ARLP036   
   From Tad Cook, K7RA   
   Seattle, WA  September 9, 2011   
   To all radio amateurs    
      
   SB PROP ARL ARLP036   
   ARLP036 Propagation de K7RA   
      
   Solar indicators rose again this week, with average daily sunspot   
   numbers increasing nearly 21 points to 104.3, and average daily   
   solar flux up nearly 12 points to 115.5.  Geomagnetic numbers were   
   up as well, with the most active geomagnetic day occurring on   
   September 3.   
      
   We are just two weeks away from the Autumnal Equinox in the Northern   
   Hemisphere.  Look for increasing enhanced HF conditions as a result,   
   as we move from Summer conditions with its associated atmospheric   
   noise and daytime absorption.   
      
   The latest prediction from NOAA/USAF has solar flux at 105 for   
   September 9-10, 100 on September 11, 95 on September 12-13, 100 on   
   September 14-15, 105 and 103 on September 16-17, and 105 on   
   September 18-22.  Planetary A index is predicted at 5 on September   
   9, 18, 15, 10 and 8 on September 10-13, 5 on September 14-17, 7 on   
   September 18-19, and 5 on September 20-23.   
      
   Geophysical Institute Prague predicts minor storm for September   
   9-10, active conditions September 11, unsettled September 12, quiet   
   to unsettled September 13, and quiet on September 14-15.   
      
   Both the NOAA and Prague predictions for September 9-10 are probably   
   based on a series of recent solar flares beginning September 6 from   
   sunspot group 1283. These should deliver minor disruptions to Earth   
   on September 9-11, because the energy isn't squarely aimed toward   
   Earth. In another few days 1283 will be over our Sun's western limb   
   and outside the area of influence for Earth. An eruption from a   
   sunspot squarely in the center of the solar image has the potential   
   for the greatest impact here. 1283 was in the center of the solar   
   disc several days ago, but no longer.   
      
   See the web site   
   http://www.space.com/12882-sun-solar-flares-faithful-sunspot.html   
   for an interesting article about sunspot group 1283. An eruption   
   from 1283 can be seen at   
   http://www.nasa.gov/mission_pages/sunearth/news/gallery/20110907   
   x1.8flare.html.   
   Note you can also select a high resolution image from that page.   
      
   Check http://www.youtube.com/watch?v=EI6sP3SVnOU for an interesting   
   video commentary on 1283.  Note that in the lower right you can   
   select a high definition image. Pay no attention to the comments   
   below the video regarding earthquakes, typhoons and planetary   
   alignment. Anyone can post these, and they are not based on any   
   sound science.   
      
   Max White, M0VNG of Worcester England sent in an article about the   
   Solar Dynamics Observatory and how they are using it to study solar   
   flares. Read it at,   
   http://www.nasa.gov/mission_pages/sdo/news/late-phase-flares.html.   
      
   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   
   http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of past   
   propagation bulletins is at   
   http://arrl.org/w1aw-bulletins-archive-propagation. Find more good   
   information and tutorials on propagation at   
   http://myplace.frontier.com/~k9la/.   
      
   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 September 1 through 7 were 119, 103, 139, 114,   
   102, 93, and 60, with a mean of 104.3. 10.7 cm flux was 111.8,   
   115.4, 118.7, 119.4, 118.7, 111.5, and 112.8, with a mean of 115.5.   
   Estimated planetary A indices were 3, 3, 13, 8, 6, 7, and 6, with a   
   mean of 6.6. Estimated mid-latitude A indices were 1, 1, 9, 7, 4, 5,   
   and 5, with a mean of 4.6.   
   NNNN   
   /EX   
      
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   IF you have questions or concerns regarding the accuracy   
   of information posted, or the opinions expressed, contact the content   
   originators directly.   All publications retransmitted as   
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   email header and other control information which   
   is not part of the actual publication.   
      
   Gentlemens' agreements ratified by IARU regions 1 and 2 have   
   designated a global "center of activity" frequency  in  each   
   of  the  international  hf  bands.  THese are similar to the   
   concept for weak signal calling and other center of activity   
   frequencies.  Three of these have been ratified worldwide.   
      
   THese  center of activity frequencies are where stations can   
   go to render or obtain emergency assistance.   
      
   WHen casually operating or  contesting  on  hf  please  make   
   yourself  aware  of  these  frequencies,  and give them some   
   space. Remember that often stations with emergency needs are   
   not  those  utilizing  high  gain antennas and maximum legal   
   power.   
      
   TO find out more, visit 14300.net or IARU web resources.   
      
      
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