TZUTC: -0500   
   MSGID: 555.fidonet-ls_arrl@1:2320/33 290e83fd   
   PID: Synchronet 3.20a-Win32 master/777fb6d8b Jun 13 2023 MSC 1929   
   TID: SBBSecho 3.20-Win32 master/777fb6d8b Jun 13 2023 MSC 1929   
   BBSID: TBOLT   
   CHRS: ASCII 1   
      
   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 7, 2023   
   To all radio amateurs   
      
   SB PROP ARL ARLP027   
   ARLP027 Propagation de K7RA   
      
   The average daily sunspot number for June, 2023 was the highest in   
   21 years, according to Spaceweather.com.   
      
   From a July 3 email alert from Spaceweather.com:   
      
   "SUNSPOT COUNTS HIT A 21-YEAR HIGH:  It's official:  The average   
   sunspot number in June 2023 hit a 21-year high.  Solar Cycle 25 has   
   shot past its predecessor, Solar Cycle 24, and may be on pace to   
   rival some of the stronger cycles of the 20th century."   
      
   Could we see another Cycle 19, the biggest in recorded history, even   
   back before the birth of radio?   
      
   Not too long ago, we heard that this cycle should peak in summer   
   2025.  Later that was revised to 2024.  Now I am seeing occasional   
   references to a cycle peak at the end of this year.   
      
   From my own records, average daily sunspot numbers for April through   
   June 2023 were 93.7, 125.8 and 143.9, a nice upward trend.   
      
   Some popular news outlets seem confused by the difference between   
   sunspot number and number of sunspots, and have quoted another   
   higher average.   
      
   Here is the difference.  If they are just counting the total number   
   of sunspots for the month, this is far different from average daily   
   sunspot numbers.  The sunspot number is somewhat subjective, but it   
   gets ten points for each sunspot group, and one point for each   
   sunspot in those groups.   
      
   But I stand by my numbers.  They are all from NOAA and appear at the   
   end of each bulletin.   
      
   But they may be referencing International Sunspot Number, which may   
   be different from the SESC numbers from NOAA.   
      
   Here is an example of confusing sunspot numbers with number of   
   sunspots:  https://bit.ly/3NCQCAl   
      
   This one is also confusing, saying there were 163.4 sunspots in   
   June.  https://bit.ly/3PMu6Ym   
      
   But what does this mean?  It could be either 163 or 164 sunspots,   
   but not a fractional number, unless it expresses an average.  The   
   minimum sunspot number is 11.  This would be one sunspot group   
   containing one spot.  They are always whole, not fractional   
   integers.   
      
   There was one new sunspot region (group) on June 30, three more on   
   July 1, one more on July 2, another on July 4, and one more on July   
   5.   
      
   Sunspot and solar flux data again this week did not track together.   
   Average daily sunspot number declined from 170 to 126.1, while   
   average daily solar flux rose slightly from 160.3 to 164.5.   
      
   Geomagnetic indicators were lower, with average daily planetary A   
   index declining from 10.7 to 7.3, and middle latitude averages from   
   9.9 to 8.   
      
   Predicted solar flux is 155 on July 7, 150 on July 8 to 10, then 155   
   on July 11, 160 on July 12 to 13, 175 on July 14 to 18, 170 on July   
   19 to 21, 160 on July 22 and 23, 155 on July 24 and 25, 160 on July   
   26 and 27, 165 on July 28 and 29, then 170, 170 and 165 on July 30   
   through August 1, 155 on August 2 to 6, then 160, 165 and 170 on   
   August 7 to 9, and 175 on August 10 to 14.   
      
   Predicted planetary A index is 5, 12 and 8 on July 7 to 9, 5 on July   
   10 and 11, then 20 and 30 on July 12 and 13, 8 on July 14 to 22, 5   
   on July 23 to 30, 8 on July 31 through August 1, then 5 on August 2   
   to 4, 12 and 8 on August 5 and 6, then 5, 20 and 30 on August 7 to   
   9, and 8 on August 10 to 18.   
      
   Note those big numbers are about one solar rotation apart, which is   
   about 27.5 days.   
      
   Weekly Commentary on the Sun, the Magnetosphere, and the Earth's   
   Ionosphere for July 6, 2023 from F. K. Janda, OK1HH.   
      
   When the current 25th solar cycle began in December 2019, solar   
   astronomers thought it would be a weak cycle similar to its   
   immediate predecessor, solar cycle 24.  But now we have a twenty-one   
   year peak.  And we expect a continued increase for about two more   
   years.   
      
   The misfortune is that ongoing global changes are reducing the   
   ionization rate of the ionosphere.  Yet the current conditions for   
   shortwave or decameter wave propagation do not match the amount of   
   solar activity - they are worse.   
      
   But that's not all.  Not only is solar cycle 25 likely to rival some   
   of the more powerful cycles of the 20th century, but we're likely to   
   see even more powerful solar flares and magnetic storms.  History   
   repeats itself cyclically, and we need only think of the great   
   Halloween storm of 2003, including the strongest solar flare ever   
   recorded in X-ray (X45).   
      
   The giant sunspot group AR3354 (only about four times smaller than   
   the giant sunspot group of early September 1859) made its last   
   appearance on July 2 with an X-class flare.  Two days later it   
   eclipsed.   
      
   We won't lose the source of the stronger flares, however - the   
   growing AR3359, with its Beta-Gamma magnetic configuration, crossed   
   the central meridian toward active western longitudes on July 6 and   
   will continue to grow.  With its predicted higher activity, we could   
   see an increase in the Earth's magnetic field activity as early as   
   the middle of next week.   
      
   Tamitha Skov, from July 1.  https://youtu.be/HR8mm30oxOQ   
      
   Blackout  http://bit.ly/46tTRT8  https://bit.ly/3rhbjdz   
      
   Stormy weekend?  https://bit.ly/3pDrT6R   
      
   Send your tips, reports, observations, questions and comments to   
   k7ra@arrl.net.  When reporting observations, don't forget to tell us   
   which mode you were operating.   
      
   For more information concerning shortwave radio propagation, see   
   http://www.arrl.org/propagation and the ARRL Technical Information   
   Service at http://arrl.org/propagation-of-rf-signals .  For an   
   explanation of numbers used in this bulletin, see   
   http://arrl.org/the-sun-the-earth-the-ionosphere .   
      
   Also, check this article from September, 2002 QST:   
      
   https://www.arrl.org/files/file/Technology/tis/info/pdf/0209038.pdf   
      
   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/   
      
   Instructions for starting or ending email distribution of ARRL   
   bulletins are at http://arrl.org/bulletins   
      
   Sunspot numbers for June 29 through July 5, 2023 were 112, 187, 119,   
   126, 117, 121, and 101, with a mean of 126.1.  10.7 cm flux was   
   162.2, 158.6, 165.5, 170.2, 173.2, 167.2, and 154.6, with a mean of   
   164.5.  Estimated planetary A indices were 17, 8, 5, 5, 5, 4, and 7,   
   with a mean of 7.3.  Middle latitude A index was 13, 8, 6, 8, 7, 5,   
   and 9, with a mean of 8.   
   NNNN   
   /EX   
   --- SBBSecho 3.20-Win32   
    * Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)   
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