[SFDXA] ARLP016 Propagation de K7RA

[Bill]

> SB PROP @ ARL $ARLP016
> ARLP016 Propagation de K7RA
> 
> ZCZC AP16
> QST de W1AW  
> Propagation Forecast Bulletin 16  ARLP016
> From Tad Cook, K7RA
> Seattle, WA  April 19, 2024
> To all radio amateurs
> 
> SB PROP ARL ARLP016
> ARLP016 Propagation de K7RA
> 
> Solar activity increased dramatically this reporting week (April
> 11-17), and thirteen new sunspot groups emerged. One appeared on
> April 11, two more on April 13, three more on April 14, another two
> on April 15, one more on April 16 and another two on April 17. On
> April 18 an additional two sunspot groups emerged, and the daily
> sunspot number increased to 247.
> 
> The daily sunspot number was 199 on April 17, the highest value
> since July 12, 2023 when it was 219. On April 18, when the sunspot
> number was 247, it was the highest sunspot number since July 6, 2014
> when it was 256. That was back in Solar Cycle 24, so 247 is a new
> record for Solar Cycle 25.
> 
> Average daily sunspot numbers jumped from 67.9 to 142.7, and average
> daily solar flux from 123.2 to 177.4.
> 
> Predicted solar flux over the near term is 225 on April 19, 220 on
> April 20-21, 215 and 205 on April 22-23, 190 on April 24-25, then
> 140, 130, 125 and 120 on April 26-29, then 125 on April 30 to May 6,
> and 130, 140, 150, 160 and 175 on May 7-11, then 180 on May 12-14,
> 175 on May 15, 170 on May 16-17, then 167 and 165 on May 18-19, 160
> on May 20-21, then 155, 140, 135, 125 and 120 on May 22-26.
> 
> Predicted planetary A index is 6, 10, 12 and 8 on April 19-22, 5 on
> April 23-27, 8 on April 28-29, 7 on April 30, 10 on May 1-3, 5 on
> May 4, 8 on May 5-7, 5 on May 8-11, 10 and 8 on May 12-13, then 5 on
> May 14-24, and 8 on May 25-26.
> 
> "Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
> Ionosphere - April 18, 2024:
> 
> "Over the past weekend, active sunspot regions began to emerge on
> the eastern limb as expected. Curiosity about what we would actually
> see was heightened because their flare activity during the last
> rotation was somewhat higher than usual. Therefore, the CME from a
> moderate eruption in the northern hemisphere of the Sun on April 11
> with a maximum at 1706 UTC was not a surprise. The arrival of the
> particle cloud on April 14 was therefore expected, but it missed the
> Earth.
> 
> "Another CME was ejected towards Earth on 12 April. Although neither
> CME was particularly strong, a G1 class geomagnetic storm was
> expected. This occurred on 16 April, so either the particle cloud
> moved more slowly or traveled along a longer path toward the Earth.
> Either way, the disturbance worsened shortwave propagation on April
> 16. But the improvement was rapid, starting as early as April 17.
> The credit for this goes to the increasing solar radiation coming
> from the active regions we can observe on the Sun this week and
> next.
> 
> "Another weak CME left the Sun on April 15, and the Earth's impact
> was calculated for April 18. However, all predictions of
> disturbances at the current stage of the 11-year cycle are
> unreliable. They are usually either late (by a day or so) or not at
> all. The important thing is the result - due to the relatively high
> solar activity and at the same time the small number of geomagnetic
> disturbances, the shortwave propagation conditions are mostly above
> average.  F.K. Janda, OK1HH."
> 
> Check out these videos and an article on flare activity from
> EarthSky:
> 
> https://bit.ly/3W4GTID
> 
> On April 16, Samuel, K5KJ called ARRL headquarters about unusual
> propagation he experienced.
> 
> He said flare activity caused a radio blackout, and on 40 meters he
> could not hear any local or regional signals.
> 
> But he noticed foreign broadcast stations from Asia with good
> signals.
> 
> He said this is just the opposite of what he expected during a
> blackout.
> 
> Durango Herald article about sunspots and prominences:
> 
> https://bit.ly/3Q3VDnh
> 
> NASA on Space Weather:
> 
> https://go.nasa.gov/49YFhDX
> 
> From Science.Nasa.gov, Solar Moss:
> 
> https://go.nasa.gov/4b3n4Wn
> 
> See sunspots with eclipse glasses:
> 
> https://bit.ly/4cXc5Qp
> 
> I tried this, but had no luck, as the images were too tiny.
> 
> The latest video from Dr. Tamitha Skov, WX6SWW, for April 14:
> 
> https://youtu.be/Z1OClNvDg2o
> 
> 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 QST article about 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 April 11 through 17 2024 were 81, 83, 115, 152,
> 193, 176, and 199, with a mean of 142.7. 10.7 cm flux was 143.7,
> 151.5, 161, 178.4, 191.9, 198.7, and 216.5, with a mean of 177.4.
> Estimated planetary A indices were 6, 7, 5, 6, 8, 31, and 7, with a
> mean of 10. Middle latitude A index was 6, 6, 6, 5, 7, 17, and 8,
> with a mean of 7.9.
> NNNN
> /EX