[SFDXA] ARLP051 Propagation de K7RA

[Bill]

> SB PROP @ ARL $ARLP051
> ARLP051 Propagation de K7RA
> 
> ZCZC AP51
> QST de W1AW  
> Propagation Forecast Bulletin 51  ARLP051
> From Tad Cook, K7RA
> Seattle, WA  December 22, 2023
> To all radio amateurs 
> 
> SB PROP ARL ARLP051
> ARLP051 Propagation de K7RA
> 
> The Winter Solstice, the shortest day of the year in the Northern
> Hemisphere occurred at 0327 UTC on December 22. It is the start of
> summer in the Southern Hemisphere.
> 
> Solar activity increased over the last reporting week (December
> 14-20), with eleven new sunspot groups emerging.
> 
> One new sunspot group appeared on December 15, four more on the
> following day, another on December 17, three more on December 18,
> and two more in December 19-20.
> 
> Average daily sunspot number rose from 110.3 to 137.4, solar flux
> from 129.8 to 162.7, planetary A index 5.6 to 18.4, and middle
> latitude A index from 4.6 to 13.7.
> 
> The most active day was Sunday, December 17 when the planetary A
> index was 36, and Alaska's college A index was 88.
> 
> The cause was what Spaceweather.com reported as the strongest flare
> of the current solar cycle, an X2.8 class, and it caused a radio
> blackout.
> 
> Here is a video of the brief flash:
> 
> https://bit.ly/3RP3xCw
> 
> Spaceweather.com reported on Wednesday that another flare is coming
> from sunspot group AR3529, and here is a movie they posted:
> 
> https://bit.ly/3tipAbr
> 
> Predicted solar flux is 190, 188 and 186 on December 22-24, then
> 182, 180, 170 and 165 on December 25-28, 145 on December 29-30, 150
> on December 31, then 145, 140 and 138 on January 1-3, 2024, then 136
> on January 4-5, then 140, 145 and 148 on January 6-8, 145 on January
> 9-12, then 150, 147, 145, 140, and 138 on January 13-17, 136 on
> January 18-19, then 140, 145 and 148 on January 20-22, then 145 on
> January 23-26, then 150, 145, 140 and 138 on January 27-30.
> 
> Predicted planetary A index is 5, 12 and 8 on December 22-24, 5 on
> December 25-29, 8 on December 30-31, then 10 and 8 on January 1-2,
> 2024, 5 on January 3-7, 10 on January 8-9, 8 on January 10, 5 on
> January 11-13, 15 on January 14, 12 on January 15-16, and 8 on
> January 17-19, then 5 on January 20-25, and 8 on January 26-27.
> 
> Jon Jones, N0JK wrote, from Kansas:
> 
> "Some winter 6 meter Es December 18-19. N7BHC (EL15) and KD5CAF
> (EL18) into EM28 for me on FT8 around 0100 UTC December 19. Earlier
> stations in Colorado, Kansas, and Missouri had ZL7DX in on 6 meters
> at 2200 UTC December 18."
> 
> Here is a new, long video from Dr. Tamitha Skov, WX6SWW, from
> earlier this week:
> 
> https://bit.ly/3GPRYET
> 
> Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
> Ionosphere - December 21, 2023 from F.K. Janda, OK1HH:
> 
> "Astronomical winter began in the Northern Hemisphere at the moment
> of the Winter Solstice: December 22 at 0327 UTC. On this day is the
> longest night and, of course, the shortest day. The total effect of
> solar X-ray and ultraviolet radiation on the ionosphere of our
> hemisphere was thus relatively the smallest of the entire year, and
> the effects of changes in the solar wind were all the more
> effective. This is also one of the reasons why, despite relatively
> high solar activity, the shortwave propagation conditions are worse
> than we would like and then we expected.
> 
> "Over the next six months, the length of the day will increase until
> the Summer Solstice on June 20. Slowly at first, then faster,
> fastest around the Spring Equinox on March 20. It is certain that
> then the propagation conditions will be significantly better than
> now. It is even possible that the maximum of the eleven-year cycle
> will occur as early as next year, although it would be better for us
> if it did not occur until 2025.
> 
> "Although we have not observed any particularly large sunspot groups
> in recent weeks, there were always one or two active regions among
> them, whose magnetic configuration allowed the development of a
> medium-sized eruption, possibly even with a CME - after all we
> observed several of these. The exception was the X2.8 class eruption
> on December 14 at 1702 UTC, the strongest so far since the beginning
> of the 25th solar cycle, or since the major disturbances in
> September 2017.
> 
> "The eruption originated in AR3514, which was approaching the
> western limb of the Sun. Even though it hurled a fast-moving CME
> into space, it was relatively unlikely to cause strong geomagnetic
> storms here on Earth. Eventually, the CME either missed Earth or hit
> so weakly that it was not detected by satellite sensors.
> 
> "During the rise of the solar flux from 126 on December 12 to 195 on
> December 20, with the corresponding increase in solar X-ray
> radiation, shortwave propagation improved only slightly, actually
> fluctuating, which was expected.
> 
> "The last geomagnetically quiet day was December 13, after which the
> Earth's magnetic field was unsettled to active (more precisely:
> active around last weekend). However, most days until the end of
> this year should be geomagnetically quieter, while the solar flux
> will remain elevated. Therefore, we can expect slightly better
> propagation."
> 
> Here are a number of articles about a Big Flare:
> 
> https://bit.ly/3RQG4Rb
> 
> https://bit.ly/3RRzBpe
> 
> https://bit.ly/48tJtuH
> 
> https://bit.ly/3TAeybV
> 
> https://bit.ly/48pIpbo
> 
> https://bit.ly/488c88X
> 
> https://bit.ly/3tymsrK
> 
> https://bit.ly/3RwJzLh
> 
> https://bit.ly/3RThBuQ
> 
> https://bit.ly/3RRzzh0
> 
> An article about Radio Blackout:
> 
> https://bit.ly/3v5b5Il
> 
> Send your tips, reports, observations, questions and comments to
> k7ra at 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 web page 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/ .
> 
> Also, check this article about understanding solar indices:
> 
> https://bit.ly/3Rc8Njt
> 
> Instructions for starting or ending email distribution of ARRL
> bulletins are at http://arrl.org/bulletins .
> 
> Sunspot numbers for December 14 through 20, 2023 were 126, 130, 163,
> 129, 137, 144, and 133, with a mean of 137.4. 10.7 cm flux was
> 155.1, 144.3, 149, 154.6, 161.4, 179.3, and 195.3, with a mean of
> 162.7. Estimated planetary A indices were 16, 12, 14, 36, 28, 12,
> and 11, with a mean of 18.4. Middle latitude A index was 13, 8, 10,
> 32, 16, 10, and 7, with a mean of 13.7.
> NNNN
> /EX