XPost: rec.radio.shortwave, rec.radio.info   
   From: memberlist@arrl.org   
      
   SB PROP @ ARL $ARLP037   
   ARLP037 Propagation de K7RA   
      
   ZCZC AP37   
   QST de W1AW   
   Propagation Forecast Bulletin 37 ARLP037   
   >From Tad Cook, K7RA   
   Seattle, WA September 27, 2024   
   To all radio amateurs   
      
   SB PROP ARL ARLP037   
   ARLP037 Propagation de K7RA   
      
   Seven sunspot groups emerged this week. The first was on September 19, three   
   on September 20, one each on September 22 and 23, and the last on September   
   25.   
      
      
   Average daily sunspot numbers increased from 120 to 137.2, and average daily   
   solar flux shifted from 175.7 to 164.3.   
      
      
   Geomagnetic numbers were much quieter. Average daily planetary A index   
   changed from 35.7 to 14.3, and middle latitude A index from 23.4 to 10.7.   
      
      
   Predicted solar flux is 180 September 27 to October 1, 190 on October 2-6,   
   185 on October 7-9, 180 on October 10, 175 on October 11-16, 170 on October   
   17-18, 165 on October 19, 160 on October 20-23, 165 on October 24-26, then   
   170 and 175 on October 27-28, 180 on October 29-30, and 190 on October 31   
   through November 2.   
      
      
   Predicted planetary A index is 5 on September 27-28, 8 on September 29-30, 5   
   on October 1-4, 10 on October 5-6, 5 on October 7-9, then 10, 20 and 19 on   
   October 10-12, and 5 on October 13-21, 8 on October 22-23, 5 on October   
   24-31, and 8 on November 1-2.   
      
      
   "Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere   
   - September 26, 2024 from OK1HH:   
      
      
   "Solar flare activity is generally lower than it was in the first half of   
   September, when M-class solar flares were common and X-class flares also   
   occurred. The last significant M-class flare, including a CME, was observed   
   on September 22. However, the Earth's magnetic field activity increased on   
   September 25-26, incidentally in good agreement with the forecast.   
      
      
   "Propagation conditions, especially in the shorter half of the shortwave   
   range, have understandably improved, but not as much as we might have   
   expected in the run-up to the equinox. This was influenced by a decrease in   
   solar activity (compared to August levels) - and of course an increase in   
   geomagnetic activity.   
      
      
   "Unlike in times relatively recently past, any of us can monitor not only   
   total solar activity, but also changes in solar wind parameters. Both its   
   speed and the concentration of free electrons and protons ejected by flares.   
   Changes in the ionosphere follow quickly, but not always in the same way. It   
   is also always the result of previous developments."   
      
      
   Latest report from Dr. Tamitha Skov, WX6SWW:   
   https://youtu.be/B9jWbAVEpZw [ https://youtu.be/B9jWbAVEpZw ]   
      
   Send your tips, reports, observations, questions and comments to   
   k7ra@arrl.net [ mailto: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   
   www.www.arrl.org/propagation [ http://www.arrl.org/propagation ] and the ARRL   
   Technical Information Service web page at,   
   www.arrl.org/propagation-of-rf-signals [   
   http://arrl.org/propagation-of-rf-signals ] .   
      
   For an explanation of numbers used in this bulletin, see   
   www.arrl.org/the-sun-the-earth-the-ionosphere [   
   http://arrl.org/the-sun-the-earth-the-ionosphere ] .   
      
      
   An archive of past propagation bulletins is at   
   www.arrl.org/w1aw-bulletins-archive-propagation [   
   http://arrl.org/w1aw-bulletins-archive-propagation ] .   
      
   More good information and tutorials on propagation are at http://k9la.us/ [   
   http://k9la.us/ ] .   
      
      
   Also, check this QST article:   
   https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ] "Understanding Solar   
   Indices" from September 2002 QST.   
      
      
   Instructions for starting or ending email subscriptions to ARRL bulletins are   
   at www.arrl.org/bulletins [ http://arrl.org/bulletins ] .   
      
      
   Sunspot numbers for September 19 through 25 2024 were 109, 113, 117, 114,   
   224, 123, and 160, with a mean of 137.1. 10.7 cm flux was 161.2, 153.8, 158,   
   162.8, 167.4, 172.4, and 174.2, with a mean of 164.3. Estimated planetary A   
   indices were 20, 7, 6, 5, 13, 17, and 32, with a mean of 14.3. Middle   
   latitude A Index was 15, 6, 6, 3, 9, 12, and 24, with a mean of 10.7.   
      
   NNNN   
   /EX   
      
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