TZUTC: -0500   
   MSGID: 367.fidonet-ls_arrl@1:2320/33 288cdaf8   
   PID: Synchronet 3.19b-Win32 master/a2a9dc027 Jan  2 2022 MSC 1928   
   TID: SBBSecho 3.14-Win32 master/a2a9dc027 Jan  2 2022 MSC 1928   
   BBSID: TBOLT   
   CHRS: ASCII 1   
      
   SB PROP @ ARL $ARLP013   
   ARLP013 Propagation de K7RA   
      
   ZCZC AP13   
   QST de W1AW    
   Propagation Forecast Bulletin 13  ARLP013   
   From Tad Cook, K7RA   
   Seattle, WA  March 31, 2023   
   To all radio amateurs   
      
   SB PROP ARL ARLP013   
   ARLP013 Propagation de K7RA   
      
   Solar activity increased this week. Average daily sunspot number   
   rose from 68 to 112.6, and average daily solar flux changed from   
   145.6 to 156.1.   
      
   A new sunspot group emerged on March 24, two more on March 26 and   
   27, and three on March 29.   
      
   Due to solar wind and a geomagnetic disturbance at the beginning of   
   the reporting week, average daily planetary A index increased from   
   10.6 to 23.3, while average middle latitude A index went from 8.4 to   
   13.7. Many reports of aurora came in this week, some down to lower   
   latitudes in North America.   
      
   Predicted solar flux is 135 on March 31, 130 on April 1-6, 132 on   
   April 7-8, then 130, 132, 135 and 135 on April 9-12, then 140, 145   
   and 148 on April 13-15, then 150, 150, 155, 155 and 158 on April   
   16-20, 160 on April 21-23, then 155, 145 and 145 on April 24-26, and   
   135 on April 27 through May 1, then 132 on May 2-5, then 130, 132,   
   135 and 135 on May 6-9.   
      
   Predicted planetary A index is 18, 16, 12, 10 and 8 on March 31   
   through April 4, then 5 on April 5-9, then 15, 12, 8 and 5 on April   
   10-13, 8 on April 14-15, then 12, 20, 15 and 5 on April 16-19, then   
   20, 15 and 10 on April 20-22, 8 on April 23-24, 5 on April 25-26,   
   then 12, 15, 10 and 8 on April 27-30, and 5 on May 1-6, then 15, 12   
   and 8 on May 7-9.   
      
   Weekly Commentary on the Sun, the Magnetosphere, and the Earth's   
   Ionosphere - March 30, 2023 from OK1HH.   
      
   "The strong geomagnetic storm on 23-24 March was not expected.   
   Moreover, it was classified as a G4, making it the most intense in   
   almost 6 years. The source of the solar wind was not identified with   
   certainty, but a large coronal hole in the south, near the central   
   meridian, could not be missed.   
      
   "As a consequence of the disturbance, the ionosphere first   
   experienced a rise in the critical frequencies of the F2 layer on 23   
   March, followed by a significant drop on 24-25 March. Their normal   
   values started to be registered again only after 26 March.   
      
   "Energetic flares are a reliable indicator of the increase in solar   
   activity. On March 29, the seventh X-class flare of the year was   
   registered. Yet a total of seven were registered in 2022 and only   
   two in 2021.   
      
   "Most of the sunspots are now on the western half of the solar disk.   
   As they gradually set, total solar activity will first decrease over   
   the next week before rising again."   
      
   Here are articles about solar activity as an existential threat:   
      
   https://bit.ly/3M28RQv   
      
   https://bit.ly/42W7xo4   
      
   https://bit.ly/40Qf6Lc   
      
   Nice sunspot video, before the aurora:   
      
   https://bit.ly/3K2alHX   
      
   AA7FV wrote on March 25:   
      
   "There was a 6-meter opening from Arizona to VK on March 24.  I   
   received VK7HH in Tasmania at 2028 UTC on WSPR; he was using just   
   0.2 watts (200 mW)."   
      
   VK7HH responded:   
      
   "Yes, that WSPR spot was from my remote station running 200 mW from   
   a Zacktek WSPR TX into a 1/2 wave vertical antenna. HASL 931m."   
      
   AA7FV wrote:   
      
   "For reference, my 50 MHz antenna is a Cushcraft 1/2-wave vertical,   
   the Ringo AR6, with its base at about 10 feet above ground. The   
   location here is 870m asl but I'm in the valley, just outside   
   Tucson. The receiver is an ancient Icom PCR1000, but with a preamp.   
   I monitor 6m 24/7, but rarely hear any signals at all, and when I do   
   hear something it's usually from someone else in Arizona."   
      
   On March 25, Jon, N0JK wrote:   
      
   "Worked VP8NO in GD18 today on 6 Meter FT8 at 1905 UTC.  de N0JK   
   EM28 in Kansas."   
      
   Jon was using a portable 2 element Yagi and running 50 watts.   
      
   Here is an article about a "Hole" in the Sun:   
      
   https://www.space.com/solar-flare-coronal-hole-space-weather   
      
   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 .   
      
   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 March 23 through 29, 2023 were 73, 108, 105,   
   125, 128, 114, and 135, with a mean of 112.6. 10.7 cm flux was 151,   
   157.5, 160.3, 159.4, 158.2, 158.7, and 147.8, with a mean of 156.1.   
   Estimated planetary A indices were 60, 66, 15, 8, 3, 5, and 6, with   
   a mean of 23.3. Middle latitude A index was 28, 40, 12, 6, 2, 4, and   
   4, with a mean of 13.7.   
   NNNN   
   /EX   
   --- SBBSecho 3.14-Win32   
    * Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)   
   SEEN-BY: 1/120 123 15/0 18/0 50/109 90/1 105/81 106/201 116/17 18   
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   SEEN-BY: 153/7715 154/10 30 40 50 700 218/700 840 220/70 90 221/1   
   SEEN-BY: 221/6 222/2 226/17 18 30 227/114 229/110 111 112 113 206   
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   SEEN-BY: 267/800 275/1000 282/1038 299/6 301/1 113 317/3 320/219 322/757   
   SEEN-BY: 335/364 341/66 342/200 396/45 460/58 467/888 633/267 280   
   SEEN-BY: 633/281 412 418 712/133 620 848 1321 770/1 100 340 772/210   
   SEEN-BY: 772/220 230 2320/0 33 105 304 401 3634/0 12 27 56 57 119   
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   PATH: 2320/33 105 154/10 3634/12 5020/1042 301/1 221/6 218/840   
   PATH: 770/1 712/848 633/280 229/426