K7RA's Solar Report Hit refresh if this report appears out of date. It is updated every friday morning. Last update: Friday, 17-May-2024 03:29:10 GMT

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SB PROP @ ARL $ARLP020
ARLP020 Propagation DE K7RA
QST DE W1AW
ARRL Propagation Bulletin 20 ARLP020 From Tad Cook, K7RA
Seattle, Washington May 17 2024
To all radio amateurs

What an amazing week this was for solar activity, geomagnetic disturbances and aurora!

Thirteen new sunspot groups emerged this reporting week, May 9-15. Two appeared May 9, three more on May 11, another four on May 12, two on May 13, one more on May 14, and another on May 15.

Average daily sunspot number rose from 138.3 to 175, and average daily solar flux from 177.6 to 220.5.

Average daily planetary A index increased from 14.4 to 71.1, while middle latitude numbers rose from 12.3 to 47.9.

Highest sunspot number was 207 on May 13, and solar flux was 233.2 on May 9.

The planetary A index was 273 on May 11, even higher than Alaska's college A index of 208.

Predicted solar flux is 200, 190 and 180 on May 17-19, 175 on May 20-22, 180 on May 23, 160 on May 24-25, then 165 and 175 on May 26-27, 195 on May 28-29, 205 on May 30-31, then 215, 220 and 225 on June 1-3, 220 on June 4-5, 225 on June 6-8, then 220, 215, 200, 190 and 180 on June 9-13, 170 on June 14-15, 160 on June 16, 165 on June 17-18, 160 on June 19-21, then back to 225 by the end of the month.

Predicted planetary A index is 15 and 8 on May 17-18, 5 on May 19-23,then 12, 8 and 5 on May 24-26, then 12, 12, 8, 5 and 8 on May 27-31, 12 on June 1-2, then 8 on June 3, 5 on June 4-8, then 10, 12 and 8 on June 9-11, 5 on June 12-18, then 8, 12 and 8 on June 19-21, and 5, 12 and 8 on June 22-24.

At 47.8 degrees north latitude, one might suppose that at my QTH in Seattle seeing aurora would be easy, but often when we have high geomagnetic activity, we are blocked by cloud cover.

But this time skies were completely clear. Friday night after attending the opera, I dropped off my date in North Seattle and drove north, hoping to find some really dark spot to the east with a clear view to the north.

This turned into a fool's errand. I couldn't seem to get to a really dark place, and soon I received photos of the aurora from my friend in the city. All she did was aim her phone camera up, and photographed the aurora overhead, as we were well within the auroral zone.

I didn't realize that I was well within the auroral zone, so looking north was not helpful. The aurora was all around us.

"Weekly Commentary on the Sun, the Magnetosphere, and the Earth'sIonosphere ' May 16, 2024 from F.K. Janda, OK1HH.'D

"By mid-May, the two huge sunspot groups, AR3663 and AR3664, are already on the far side of the Sun. But the latter is now visible from Mars. The active regions are so large that they can be observed by the Perseverance Rover's camera, which is primarily designed to warn of Martian sandstorms. So we've got something to look forward to when it appears on the eastern edge of the solar disk.

"But on May 10, both active regions were still visible from Earth, and the activity of AR3664 (which has since merged with AR3668) caused the largest geomagnetic storm in nearly 20 years. The disturbance was in the G5 category, which is an extreme event and thus one of the 20 largest storms in the last 500 years. The fact that the disturbance started after two days of calm, contributed to the appearance of strong, widespread and beautiful auroras, observable even at low latitudes, from where "via aurora" connections could be established on two meters.

"The largest known and described disturbance on September 1, 1859 (in Cycle No. 10) is referred to as the "Carrington Event". It was caused by a sunspot group which we call the "Carrington group". AR3664 closely approximated it in size. But this time it didn't produce a CME as large and as well directed toward Earth as it did then. Thank God.

"The setting AR3664 still managed to launch the most powerful solar flare of the current solar cycle on May 14 - an X8.7 category eruption from behind the Sun's western limb. But it was actually more than Earth's measured "X8.7" - AR3664 was already beyond the western limb of the solar disk.

"High solar activity continues, and Earth has been bombarded by a rain of solar-origin protons in past days as well. Although high solar activity causes the opening of the upper shortwave bands, the high frequency of disturbances and the influx of particles from solar flares result in unstable propagation and frequent occurrence of enhanced attenuation due to the presence of inhomogeneities, not only in the lower layers of the ionosphere.'D

https://tecscience.tec.mx/en/tech/solar-flares-aurora/

https://tinyurl.com/yt7a4ymy

https://tinyurl.com/npz2sbaa

Paul Alexander, K6PFA sent this tip:

"On June 12th the NOAA-NASA Office of Space Weather Observations (SWO) will present information by and for the space weather community. You should be able to register for the public sessions at the following link:

https://cpaess.ucar.edu/meetings/noaa-nasa-swo-summit "

In a May 15 email, Jon Jones, N0JK wrote:

"Quite the geomagnetic storm and Aurora.

"I was at work Friday west of Topeka, KS when the CME hit. I was able to get on for a short while around 2240 UTC. Yaesu FT-710 and half-wave whip on car. Worked K3PA on 6M AU CW by keying the mic. Heard many on SSB including W4HLR (EM56) and KZ4TT (EM60) really strong on Aurora. EM60 is pretty far south for Aurora!

"Then F2 on 6 Meters.

"I logged KP4JRS FK68 on FT8 at 2307 UTC. Copied YV1GIY, 9Y4D, HK3W, WP4JMN and WP4RF. Interesting to hear the clear FT8 tones of the DX stations and then distorted AU signals of stateside stations calling them. The AU signals didn't decode on FT8. I decoded some USA stations on FT8 F2 back-scatter such as N0TB, K0TPP, etc. The Aurora and F2 quit abruptly here at 2310 UTC. Came back later (weaker) around 0200 UTC. I worked KB0EO EN34, N0LL EM09 and N0AV EN32 on 6M AU CW fixed portable. Had the hand key this time. Then took pictures.'D

In a May 14 email, Mark Earle, WA2MCT wrote:

"Sunday, 5/12, 6m was open. I'm in EL09 (Central Texas) with a dipole and 50w.

"10m has been open much of the day, recently, but was shut down for this event.

"Worked some 6m stations in FL WA3LXD EL99 and K4NYX EL97."

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 May 9 through 15 2024 were 170, 156, 148, 186, 207, 185, and 173 with a mean of 175. 10.7 cm flux was 233.2, 223.4, 213.7, 221.8, 215.4, 219.8, and 216, with a mean of 220.5. Estimated planetary A indices were 7, 118, 273, 54, 30, 6, and 10, with a mean of 71.1. Middle latitude A index was 7, 80, 175, 31, 24, 8, and 10, with a mean of 47.9. NNNN