SB PROP @ ARL $ARLP022   
   ARLP022 Propagation de K7RA   
      
   ZCZC AP22   
   QST de W1AW     
   Propagation Forecast Bulletin 22  ARLP022   
   From Tad Cook, K7RA   
   Seattle, WA  June 1, 2012   
   To all radio amateurs    
      
   SB PROP ARL ARLP022   
   ARLP022 Propagation de K7RA   
      
   Average daily sunspot numbers sank more than 28 points this week   
   (nearly 26%) to 81.9. Average daily solar flux declined more than 16   
   points to 111.6. This is for the seven days of May 24-30, and is   
   compared to the previous seven days, May 17-23.   
      
   No new sunspots appeared over the five days of May 26-30, but on May   
   31, three new sunspot groups appeared. One day earlier the sunspot   
   number was 78, while the total relative sunspot area was 400. On May   
   31 those numbers dropped to 73 and 330, even with the new spots.   
      
   On May 30, sunspot groups 1486, 1488, 1490 and 1492 were in place.   
   By May 31, 1486 and 1488 disappeared, and new sunspot groups 1493,   
   1494 and 1495 emerged. But the total area of all visible spots was   
   less than the day before.   
      
   You can track the fading of sunspot groups and the emergence of new   
   ones at http://www.swpc.noaa.gov/ftpmenu/forecasts/SRS.html. The   
   dates shown are always for the new UTC day, the one following the   
   day for which the data is shown. So the report marked June 1 is   
   actually displaying data gathered on May 31.   
      
   In this report the area for each sunspot group is listed, and this   
   is expressed in millionths of a solar hemisphere.  The total sunspot   
   area for the day, along with the sunspot number, is displayed along   
   with solar flux resolved to whole numbers at   
   http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt.   
      
   The short term outlook is revised from the one given in yesterday's   
   ARRL Letter, with solar flux peaking around 125 on June 2-7, hitting   
   a minimum of 105 on June 27-28, then peaking at 120 on July 1-12.   
      
   The latest prediction has solar flux at 120 on June 1, 125 on June   
   2-7, 120 on June 8-15, 115 on June 16-18, 110 on June 19-26, and   
   105, 105, 110 and 115 on June 27-30, then 120 on July 1-12.   
      
   Predicted planetary A index is 5 on June 1-2, then 10, 15, 18, 15   
   and 10 on June 3-7, 5 on June 8-11, 8 on June 12-13, 5 on June   
   14-17, and 15, 12 and 8 on June 18-20, and 5 on June 21-25.   
      
   With the start of a new month, we can revisit our moving averages   
   for sunspot numbers. We've been observing a three-month moving   
   average, based on whole calendar months, so the latest average is   
   for March, April and May 2012. About a month ago we were reporting   
   for the months of February, March and April. It is a simple   
   arithmetic - with an accent on the third, rather than second   
   syllable - average, with a total of all sunspot numbers divided by   
   the number of days in the period.   
      
   So over September 1 through November 30, 2011, there were 91 days   
   and the sum of all daily sunspot numbers for that period was 10,808,   
   yielding an average daily sunspot number of 118.8 when the sunspot   
   number total is divided by the number of days.  The next period   
   covered October 1 through December 31, 2011, with a total sum of all   
   daily sunspot numbers of 10,913 divided by 92 days, giving us an   
   average daily sunspot number of 118.6. That period in Fall 2011 had   
   the highest sunspot numbers seen so far in Cycle 24.   
      
   The three month moving averages of daily sunspot numbers for the   
   three month periods ending January 2010 through May 2012 were 15,   
   22.4, 25.7, 22.3, 18.5, 16.4, 20.4, 23.2, 28.9, 33, 35.6, 31, 30.1,   
   35.3, 55.7, 72.3, 74.4, 65.9, 61.5, 63, 79.6, 98.6, 118.8, 118.6,   
   110, 83.3, 73.7, 71.2, and 87.3. As you can see, the numbers are up   
   slightly over the past few months.   
      
   The monthly average sunspot numbers for February through May 2012   
   are 50.1, 78, 84.5 and 99.4.   
      
   Go to   
   http://phys.org/news/2012-05-science-nugget-solar-particles-infiltrating.html   
   to read an article on Ground Level Enhancements, or GLE, a rare   
   event in which a sudden rise in neutrons coincides with an energetic   
   solar flare or coronal mass ejection. A GLE detected on May 17 was   
   the first GLE of the current solar cycle.   
      
   Dave Blood, W1AFC of Oberlin, Ohio had some comments on WA8MEA's   
   recent query on LUF and MUF. Dave wrote, "MUF is affected by solar   
   UV light mostly and therefore is governed by the daily solar flux   
   levels. The LUF, as mentioned, is set by daytime absorption in the   
   D-region at about 100 km heights (hence by the number of radio wave   
   passes through it (up and down) and the number of ionospheric hops   
   supported by the F-region at 300 km heights). The absorption is   
   altered by the instantaneous X-ray radiation from the Sun and this   
   can vary up and down highly during solar flare activity. Radio   
   'Blackout' conditions occur when the absorption is so high that the   
   LUF exceeds MUF for any propagation path distance for long periods   
   from 20 minutes to several hours."   
      
   Dave worked for Raytheon for several decades on over-the-horizon   
   radar from 1960-1992. Dave has been a ham for 60 years.   
      
   Rick McCurdy, WA1GTP is in FN31si in Ivoryton, Connecticut.  He   
   wrote, "On May 23 at 1550 UTC I received RADAR on 432.100, first   
   time in years!  Heading was WSW from (Essex) New London/New Haven   
   CT area. Very few openings on 6 meters but April 30 worked short E   
   skip to VE2DLC, FN58rk, 527 miles. Also Florida openings May 24, not   
   much else."   
      
   We received another geomagnetic forecast from F.K. Janda, OK1HH.  He   
   predicts quiet to active conditions on June 1, quiet on June 2,   
   quiet to unsettled June 3-4, quiet to active June 5, active June   
   6-7, quiet to active June 8-9, quiet to unsettled June 10, quiet   
   June 11-12, quiet to active June 13, mostly quiet June 14, quiet to   
   unsettled June 15-16, quiet to active June 17, mostly quiet June 18,   
   active June 19, and quiet to unsettled June 20-21.   
      
   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 May 24 through 30 were 96, 86, 70, 83, 87, 73,   
   and 78, with a mean of 81.9. 10.7 cm flux was 115.5, 117.2, 110,   
   110.7, 110.3, 106.3 and 111, with a mean of 111.6. Estimated   
   planetary A indices were 8, 6, 4, 4, 6, 6, and 6, with a mean of   
   5.7. Estimated mid-latitude A indices were 11, 8, 5, 3, 3, 5, and 5,   
   with a mean of 5.7.   
   NNNN   
   /EX   
      
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