SB PROP @ ARL $ARLP039   
   ARLP039 Propagation de K7RA   
      
   ZCZC AP39   
   QST de W1AW     
   Propagation Forecast Bulletin 39  ARLP039   
   From Tad Cook, K7RA   
   Seattle, WA  October 1, 2010   
   To all radio amateurs    
      
   SB PROP ARL ARLP039   
   ARLP039 Propagation de K7RA   
      
   HF radio conditions were good over this past week, with average   
   daily sunspot numbers up more than five points to 45.3, and average   
   solar flux rising 1.5 points to 84.4.  On Wednesday, September 29   
   solar flux was 90.7.  The last time flux values were nearly this   
   high was August 7 at 90.5, and it last topped this value at 91.8 on   
   March 13, 2010.   
      
   A coronal wind on September 24 provided the moderate geomagnetic   
   activity for the week, with the planetary A index rising to 13.   
      
   With the end of September comes the opportunity to examine some   
   average sunspot numbers based on calendar months.  These numbers   
   look good.  Every month since early 2007 we have taken a 3-month   
   moving average of sunspot numbers.  The hope in the beginning was to   
   help us spot the bottom of the sunspot cycle without resorting to   
   smoothed sunspot numbers, which average a year of sunspot data.  But   
   three months of data allows a lot of smoothing of short term   
   variation.   
      
   Now at the end of September we know the 3-month average centered on   
   August, taking all the data from July, August and September.  It is   
   a simple arithmetic average in which we add all the sunspot numbers   
   together, then divide the sum by the number of days in those 3   
   months the data was taken from.   
      
   The three-month moving averages of daily sunspot numbers for October   
   2008 through August 2010 were 4.5, 4.4, 3.6, 2.2, 2, 1.5, 2, 4.2,   
   5.2, 4, 4, 4.6, 7.1, 10.2, 15.2, 22.4, 25.7, 22.3, 18.5, 16.2, 20.4,   
   23.2 and 28.9.  This takes into account all of the daily sunspot   
   numbers from September 1, 2008 through September 30, 2010.  It is   
   clear that there was a minimum centered around April through July   
   2008, and that for the past few months numbers have risen steadily.   
   The monthly averages for August and September 2010 were 28.2 and   
   35.7.   
      
   For this week NOAA and USAF predict quiet geomagnetic conditions   
   with a planetary A index of 5 on October 1-2, 7 for October 3-5, and   
   5 again on October 6-10.  Geophysical Institute Prague sees quiet   
   conditions October 1-3, unsettled October 4-5, and quiet October   
   6-7.   
      
   Dave Fisher, KA2CYN of New City (Rockland County) New York says he   
   had a very active weekend in the CQ World Wide RTTY Contest last   
   weekend, September 25-26.  With a 4-band roof-mounted rotatable   
   dipole and low power on 40-10 meters he made 513 contacts overall,   
   with 6 contacts into South America on 10 meters, and 161 QSOs into   
   North America on 40 meters.  20 meters was the best band into   
   Europe, with 101 QSOs on that band.   
      
   Andy Gudas, N7TP of Amargosa Valley, Nevada wrote: "Since we have   
   now entered the 'Solar Cycle That Couldn't,' is there any way to   
   compare where we think we are in the new sunspot cycle with an   
   average cycle, or maybe a really poor cycle?  I think we're   
   something like two years into the new cycle and not much is   
   happening."   
      
   Check http://www.solen.info/solar/cyclcomp.html for a graphic   
   comparison of Cycles 21-23, with the beginning of Cycle 24 plotted.   
   The time axis is marked in months since the start of the cycle,   
   which could be somewhat subjective.  Note that smoothed sunspot   
   numbers are displayed here, and since that takes a year of data to   
   compute, the latest number always lags the current date by about six   
   months.  The latest update of this chart as of October 1 was   
   September 4.   
      
   You can see another comparison at   
   http://www.solen.info/solar/solcycle.html, and note that Cycle 24 is   
   just a little squiggly line to the right of Cycle 23.  This page   
   says the current forecast is for the current cycle to peak in 2013   
   with a smoothed sunspot number of 50-70.  If that turns out to be   
   true, it will be a much lower cycle than previous ones.   
      
   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://mysite.ncnetwork.net/k9la/index.html.   
      
   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 23 through 29 were 34, 34, 40, 57, 52,   
   49, and 51 with a mean of 45.3. 10.7 cm flux was 84.3, 82.6, 82.9,   
   83.9, 83, 83.2 and 90.7 with a mean of 84.4. Estimated planetary A   
   indices were 5, 13, 7, 6, 6, 7 and 5 with a mean of 7. Estimated   
   mid-latitude A indices were 6, 9, 5, 8, 5, 7 and 2 with a mean of 6.   
   NNNN   
   /EX   
   .   
      
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   Providing   emergency   communications  assistance  to  your   
   neighbors and community isn't just a good thing to do,  it's   
   the first and foremost activity recognized in the U.s. rules   
   governing amateur radio in 47 CFR section 97.1. IF you enjoy   
   amateur  radio  remember  that  this  is  an  obligation you   
   tacitly agreed to when you acquired your license.   
      
      
      
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