K7RA's Solar Report Hit refresh if this report appears out of date. It is updated every friday morning. Last update: Friday, 19-Apr-2024 07:27:13 GMT

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SB PROP @ ARL $ARLP016
ARLP016 Propagation DE K7RA
QST DE W1AW
ARRL Propagation Bulletin 16 ARLP016 From Tad Cook, K7RA
Seattle, Washington April 19 2024
To all radio amateurs

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 cycle 24, so 247 is a new record for 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 the videos and article on flare activity.

https://bit.ly/3W4GTID

On April 16, 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.

Sunspots and prominences.

https://bit.ly/3Q3VDnh

NASA on Space Weather.

https://go.nasa.gov/49YFhDX

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.

Dr. Tamitha Skov, April 14.

https://youtu.be/Z1OClNvDg2o

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 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.

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