SB PROP @ ARL $ARLP027   
   ARLP027 Propagation de K7RA   
      
   ZCZC AP27   
   QST de W1AW     
   Propagation Forecast Bulletin 27  ARLP027   
   From Tad Cook, K7RA   
   Seattle, WA  July 8, 2011   
   To all radio amateurs    
      
   SB PROP ARL ARLP027   
   ARLP027 Propagation de K7RA   
      
   Average daily sunspot numbers for the past week dropped less than a   
   point (from 42 to 41.6) compared to the previous week, and average   
   daily solar flux was down over 5 points to 86.2.   
       
   Predicted solar flux for the near term is lower than of late, with   
   values at 88 for July 8, 90 on July 9-11, 92 on July 12-13, 94 on   
   July 14 then 90 on July 15-17, then 88 on July 18-21 and 86 on July   
   22-29.   
       
   Predicted planetary A index for July 8-13 is 7, 10, 5, 5, 7, and 7,   
   followed by 5 on July 14-18.  This is followed by a rise in   
   geomagnetic activity on July 19-24 with planetary A index at 7, 8,   
   12, 15, 10 and 7.   
       
   The latest smoothed sunspot number prediction on page 13 at   
   http://www.swpc.noaa.gov/weekly/pdf/prf1870.pdf shows the numbers   
   for December 2010 through December 2011 slightly lower. Last month's   
   prediction showed smoothed sunspot numbers for that period at 30,   
   34, 38, 41, 45, 49, 54, 59, 63, 66, 68, 71 and 74.  The latest has   
   the values for those same months changed to 29, 32, 36, 39, 43, 47,   
   52, 57, 61, 64, 66, 69 and 72.  The reason that in July we see last   
   December's number change is because the smoothed sunspot number   
   represents an average of data over one year.  The data for   
   approximately six months after December 2010 wasn't completely known   
   until the end of June, and each successive month after that contains   
   one more month of predicted data, instead of data that is actually   
   measured.   
       
   Geophysical Institute Prague predicts unsettled activity on July 8,   
   quiet July 9, unsettled July 10-11, quiet to unsettled July 12, and   
   quiet July 13-14.   
       
   NASA has a new (monthly) solar cycle prediction.  Because these are   
   not archived and the URL never changes, tracking the updates can be   
   a bit daunting, but here are the changes from a month ago.   
       
   In paragraph 9, this sentence: "We find a starting time of May 2008   
   with minimum occurring in December 2008 and maximum of about 59 in   
   June/July of 2013" in last month's prediction changed to "We find a   
   starting time of October 2008 with minimum occurring in December   
   2008 and maximum of about 69 in June/July of 2013" in this month's.   
   So they now believe the cycle started five months later than   
   previously reported, and that the smoothed sunspot peak will be 10   
   points or seventeen percent higher.  These are international sunspot   
   numbers, not the Boulder numbers used in this bulletin, which are   
   higher.   
       
   Also changed at the end of that same paragraph, from last month's   
   prediction: "At this phase of cycle 24 we now give 40 percent weight   
   to the curve-fitting technique of Hathaway, Wilson, and Reichmann   
   Solar Physics  151, 177 (1994).  That technique currently gives   
   highly uncertain (but smaller) values to Ohl's method" to "At this   
   phase of cycle 24 we now give 50 percent weight to the curve-fitting   
   technique of Hathaway, Wilson, and Reichmann Solar Physics  151, 177   
   (1994).  That technique currently gives somewhat uncertain (but   
   similar) values to Ohl's method" in the latest prediction.  So 40   
   percent was changed to 50 percent, and "smaller" was changed to   
   "similar".   
       
   Joe Molon, KA1PPV of Stamford, Connecticut likes to play around with   
   lower power on digital modes, and was running 1.5 watts with PSK-31   
   at 0101z on July 1 when he worked Ukrainian station UX7MX on 20   
   meters.  I think he must use a simple wire antenna, because when I   
   look at an image of his QTH using the hi-resolution images on Bing   
   Maps, I don't see a tower and Yagi.  Or perhaps he uses a vertical.   
   Later that same evening he logged stations in Belarus and France.   
   You can see some nice photos of UX7MX if you log into QRZ.com and go   
   to http://www.qrz.com/db/ux7mx.   
       
   In the current July 2011 issue of CQ Magazine, Tomas Hood, NW7US for   
   his monthly Propagation column has this headline:  "Don't Believe   
   the Pessimistic Forecasts!" complete with exclamation point.  He   
   points out that predictions have been all over the place and are   
   revised frequently.  He also notes that some might be tempted to   
   just turn off the radio because of forecasts, but this is   
   self-defeating, because if stations aren't listening and   
   transmitting, then there is nothing to work.  I would also note that   
   while marvelous new tools for solar observation exist now that even   
   a decade ago we didn't have, there just hasn't been enough data   
   (only 23 sunspot cycles so far) to make predictions with complete   
   reliability.  Maybe after another millennia!   
       
   On his website (http://prop.hfradio.org/) NW7US has similar info to   
   material in his column about the importance of x-rays in enhancing   
   ionospheric propagation.  Just page down a little way to "More about   
   Background X-rays".   
        
   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 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 June 30 through July 6 were 34, 51, 54, 42, 44,   
   30, and 36, with a mean of 41.6. 10.7 cm flux was 89.2, 87.6, 85.6,   
   86.2, 85, 84.8, and 84.6, with a mean of 86.1. Estimated planetary A   
   indices were 6, 13, 6, 8, 11, 14, and 8, with a mean of 9.4.   
   Estimated mid-latitude A indices were 3, 7, 3, 6, 7, 8, and 7, with   
   a mean of 5.9.   
   NNNN   
   /EX   
      
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