10M and Geomagnetic Storms

 

My efforts to document 10 M propagation are listed in this post.

03/14/25 0530Z

Another day of a geomagnetic storm. As of 0000Z, the Kp index has advanced to 6 from 5. This does not bode well for 10 M. See https://www.spaceweatherlive.com/en/auroral-activity/kp-index.html for current conditions.

03/13/25 0239Z

Today, the Kp index is 5, my 10 M band goes quiet. This is a G1 Geomagnetic storm. I have a beacon located at DN40ap. Through this day, the only responses have been from HI and Costa Rica. The Reverse Beacon Network indicates little activity in the northeast of the US. Very few signals across the band. The only signal I hear is a beacon only 5 miles from me. I expect that is ground wave. So it seems the ionosphere is not propagating my signals. Is this due to absorption or to the 10 M signals simply going through and not being reflected. Explain this.

Perplexity's Answer

When the Kp index is 5, indicating a G1 geomagnetic storm, it can significantly affect radio propagation, particularly on the 10-meter band. The lack of activity you're observing is likely due to a combination of absorption and altered ionospheric conditions.

1. : During geomagnetic storms, the ionosphere's lower layers, especially the D-layer, become more ionized. This increased ionization leads to higher absorption of radio signals, particularly those in the HF range, including the 10-meter band. Signals may be absorbed rather than reflected back to Earth, reducing their propagation distance and effectiveness 45.

2. : The ionosphere's ability to reflect radio signals is also affected. Normally, the ionosphere acts as a mirror for HF signals, allowing them to bounce back to Earth. However, during geomagnetic storms, the ionosphere's structure and density can change, potentially reducing its reflectivity. This means that signals might pass through the ionosphere without being reflected back, leading to poor propagation 57.

• : The 10-meter band typically performs well during daylight hours due to the ionosphere's increased reflectivity. However, during geomagnetic storms, this reflectivity can be disrupted, leading to poor propagation even during the day 7.

• : The fact that you can hear a beacon only 5 miles away suggests that ground wave propagation is working, as it does not rely on ionospheric reflection. Ground waves propagate along the Earth's surface and are less affected by ionospheric conditions 6.

• The lack of responses from the northeast US and the limited activity on the Reverse Beacon Network indicate that the geomagnetic storm is affecting propagation across a wide area. The signals you received from HI and Costa Rica might be due to specific ionospheric conditions or paths that were less affected by the storm.

In summary, the quietness on the 10-meter band during a G1 geomagnetic storm is likely due to both increased absorption and reduced reflection of signals by the ionosphere. Ground wave propagation remains effective for local signals but does not help with long-distance communication.

Citations:

1. https://www.spaceweatherlive.com/en/help/the-kp-index.html
2. https://mavicpilots.com/threads/kp-index-5-33.145952/
3. https://ham.stackexchange.com/questions/1225/what-are-the-general-effects-of-a-geomagnetic-storm-on-propagation
4. https://www.zl2al.com/1377/propagation-primer-101/
5. https://www.taitcommunications.com/en/about-us/news/geomagnetic-storm-impacts-radio-communications-power-grids
6. https://vu2nsb.com/radio-propagation/ground-wave-propagation/surface-wave-propagation/
7. https://strykerradios.com/10-meter-radio/introduction-to-10-meter-band/
8. https://www.swpc.noaa.gov/products/planetary-k-index
9. https://www.pa9x.com/propagation/
10. https://www.reddit.com/r/HamRadio/comments/11zmioe/i_never_hear_local_10m_stations_its_always_from/
11. https://en.wikipedia.org/wiki/10-meter_band
12. https://watchers.news/2024/12/17/cme-impacts-earth-geomagnetic-storm-december-17-2024/
13. https://www.swpc.noaa.gov/noaa-scales-explanation
14. https://3fs.net.au/making-sense-of-solar-indices/
15. https://www.reddit.com/r/amateurradio/comments/1co2eg4/solar_flares_and_hf_propagation/
16. https://en.wikipedia.org/wiki/K-index
17. https://forum.dji.com/thread-203507-1-1.html
18. https://www.swpc.noaa.gov/phenomena/geomagnetic-storms
19. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020SW002641
20. https://www.swpc.noaa.gov/content/tips-viewing-aurora
21. https://thehill.com/homenews/nexstar_media_wire/4552740-severe-geomagnetic-storm-conditions-impacting-earth-noaa-says-what-to-know/
22. https://www.arrl.org/news/propagation-update
23. https://yuneecpilots.com/threads/just-how-important-is-the-kp-index.3954/
24. https://www.swpc.noaa.gov/phenomena/solar-flares-radio-blackouts
25. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JA028261
26. http://forums.radioreference.com/threads/x-class-solar-flare-10-28.433711/
27. https://en.wikipedia.org/wiki/Geomagnetic_storm
28. https://www.radioddity.com/blogs/all/how-meteorology-shapes-hf-radio
29. https://austinhams.org/solarwxintro/
30. https://www.sws.bom.gov.au/Educational/1/2/5
31. https://hamstudy.org/browse/E3_2019/G3A
32. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023SW003500
33. https://reflector.sota.org.uk/t/geomagnetic-storm-g4/35293
34. https://www.okdxf.eu/files/NM7M_HF_Propagation_tutorial.pdf
35. http://forums.radioreference.com/threads/hf-lf-propagation-question.464386/
36. https://www.youtube.com/watch?v=yD92cmm-3kQ
37. https://resources.pcb.cadence.com/blog/2023-understanding-rf-propagation-types-and-properties
38. https://www.boldmethod.com/learn-to-fly/navigation/shoreline-effect/
39. https://www.reddit.com/r/amateurradio/comments/r6fyk0/question_about_10m_propagation_in_poor_conditions/
40. https://en.wikipedia.org/wiki/Ground_wave
41. https://chieftain.training/radio-propagation/
42. https://ham.stackexchange.com/questions/22708/a-first-homebrew-design-band-antenna-and-ground-wave-propagation
43. https://groups.google.com/g/rec.radio.amateur.antenna/c/sqn1ay7YU84
44. https://en.wikipedia.org/wiki/Radio_propagation
45. https://www.qsl.net/wj5o/10meterband.htm
46. http://www.wa2ooo.com/propagation.html
47. https://gbarc.ca/Week%203%20-%20Chapter%206%20-%20Propagation.pdf
48. https://www.droneacademy.com/what-is-kp-index/
49. https://clouglobal.com/navigating-the-storm-understanding-geomagnetic-storms-and-their-impact-on-the-power-grid/
50. https://www.swsc-journal.org/articles/swsc/pdf/2012/01/swsc120026.pdf
51. https://www.d1store.com.au/lounge/content/what-do-kp-numbers-mean-how-does-it-affect-drone-flying
52. https://www.nature.com/articles/s41598-023-45900-y
53. https://www.frontiersin.org/journals/astronomy-and-space-sciences/articles/10.3389/fspas.2024.1462160/full
54. https://moonrakeronline.com/us/blog/when-solar-storms-strike-how-hams-ride-the-ionospheric-rollercoaster
55. https://www.swpc.noaa.gov/content/global-d-region-absorption-prediction-documentation
56. https://hamstudy.org/browse/CA_B_2014/L11
57. https://peer.asee.org/the-d-and-f-ionosphere-layers-why-are-am-broadcast-signals-mostly-local.pdf
58. https://ham.stackexchange.com/questions/17260/sanity-check-should-i-be-able-to-hear-this-20m-beacon

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Answer from Perplexity: https://www.perplexity.ai/search/today-the-kp-index-is-5-my-10-8_4QSa61Raezd7F9ttnH6w?utm_source=copy_output