Schumann resonance variations during solar eclipses and cosmic events

Events on the Sun do change the Schumann resonance, but only slightly. Solar X-ray bursts have raised the first peak by about 0.2 Hz while they lasted, and solar particle events have shifted it by roughly 0.15 to 0.6 Hz. Solar eclipses are much less studied: measured eclipse effects in this frequency range are rare, and a 2015 study described its result as the first such observation.

Why the Sun matters to the resonance

The Schumann resonance lives in the cavity between the ground and the ionosphere. Lightning, about 50 flashes every second worldwide, feeds it energy. The ionosphere forms the upper wall, and its height and conductivity help set where the resonance peaks sit and how sharp they are (Price 2016).

The ionosphere is ionised mostly by radiation from the Sun. So anything that suddenly changes that radiation, or adds energetic particles, can nudge the resonance. Price (2016) lists effects detected during cosmic gamma-ray bursts, solar flares and solar proton events, and over the 11 year solar cycle.

The resonance also changes every day without any special event. Tomsk, which has monitored it since 1997, reports regular daily and seasonal patterns in all four peaks it tracks (sos70.ru). Any claimed “event effect” has to stand out from that normal rhythm.

Solar flares: small upward shifts

X-ray bursts in 2001. At stations in the Kola Peninsula and on Kamchatka, every intense solar X-ray burst studied came with an increase of about 0.2 Hz in the first peak, in at least one magnetic component, lasting as long as the burst. In most events, the second peak rose by about 0.3 Hz on average (Roldugin et al. 2004).
The X5.4 flare of 7 March 2012. A station in China recorded the first peak rising by 0.1 to 0.2 Hz during the X-ray burst (Zhou and Qiao 2015).

These are real, measurable effects. They are also tiny: a few tenths of a hertz on a peak near 7.8 Hz.

Solar particle events: shifts in both directions

When the Sun sends out bursts of energetic protons, results depend on the station and the event:

In the Kola Peninsula, the first peak dropped by about 0.15 Hz at the height of four solar proton events in 1997 and 1998 (Roldugin et al. 2001).
During the same 2012 event mentioned above, the first peak in one magnetic component dropped by up to about 0.6 Hz while the proton flux was high (Zhou and Qiao 2015).
At Arrival Heights in Antarctica, a study of the nine strongest proton events of solar cycle 22 found the first resonance frequency increasing during high-energy particle precipitation (Schlegel and Füllekrug 1999).

The honest reading: particle events disturb the upper wall of the cavity, and what a given station sees depends on where it is and what exactly the particles do.

Solar eclipses: very little data

During an eclipse, the Moon blocks part of the Sun’s radiation over the area under its shadow for a limited time. That can change the lowest layer of the ionosphere locally. Whether a global resonance notices is a harder question, and there are few measurements.

The clearest study we found is about the total eclipse of 20 March 2015 (Tereshchenko et al. 2015). It did not measure the Schumann resonance itself. It tracked an artificial 82 Hz radio signal sent along paths of 450 to 1,200 km in the far north. The signal strength at the distant receivers changed with the amount of sunlight and the height of the Sun along the path. The authors put this down to the lowest ionospheric layer (the D layer) effectively moving higher, as seen before at higher radio frequencies, and describe it as the first time this effect was observed in the extremely low frequency range during a total eclipse.

So:

An eclipse can change low frequency radio propagation along paths under its shadow.
We found no published measurement showing a clear eclipse signature in the global Schumann resonance.
A bright patch on the Tomsk chart during an eclipse is much more likely to be something the station itself describes: a local thunderstorm (white vertical stripes), missing data (black stripes) or man-made interference (thin horizontal lines) (sos70.ru).

Events beyond the Sun

Price (2016) mentions effects of cosmic gamma-ray bursts on the resonance frequencies. Beyond that, claims about galactic alignments, the galactic centre or long cycles such as the precession of Earth’s axis “tuning” the resonance have no measurements behind them that we know of.

How to watch for real effects yourself

Check NOAA first. Flares, particle events and geomagnetic storms are reported by the NOAA Space Weather Prediction Center. On this site, the Kp index page shows the geomagnetic side.
Expect small changes. The published effects are tenths of a hertz. On a colour chart that spans 0 to 40 Hz, such shifts are hard to see by eye.
Compare with the normal day. Put the day in question next to the days before it. The daily pattern repeats, and a real effect should stand out from it.

Frequently asked questions

Does a solar eclipse change the Schumann resonance? An eclipse can change low frequency radio propagation under its shadow, as a 2015 study showed with an 82 Hz test signal. We found no measurement showing a clear effect on the global Schumann resonance.

Do solar flares change the Schumann frequency? Yes, slightly. Strong X-ray bursts have raised the first peak by about 0.1 to 0.2 Hz while they lasted.

Can a solar storm push the resonance to 40 Hz? No. Measured shifts are fractions of a hertz. See our guide to today’s Schumann reading for why charts sometimes seem to show otherwise.

Do eclipses or cosmic events affect people through the resonance? We know of no study showing that. The effects on the resonance itself are small, and research on health links concerns geomagnetic activity in general, not eclipses. See is the Schumann resonance scientifically proven for the evidence.

Sources

Price, C. (2016). ELF Electromagnetic Waves from Lightning: The Schumann Resonances. Atmosphere 7(9), 116. doi:10.3390/atmos7090116
Roldugin, V. C. et al. (2004). Schumann resonance frequency increase during solar X-ray bursts. Journal of Geophysical Research: Space Physics 109(A1). doi:10.1029/2003JA010019
Roldugin, V. C., Maltsev, Y. P., Petrova, G. A., Vasiljev, A. N. (2001). Decrease of the first Schumann resonance frequency during solar proton events. Journal of Geophysical Research 106(A9), 18555 to 18562. doi:10.1029/2000JA900118
Schlegel, K., Füllekrug, M. (1999). Schumann resonance parameter changes during high-energy particle precipitation. Journal of Geophysical Research 104(A5), 10111 to 10118. doi:10.1029/1999JA900056
Zhou, H., Qiao, X. (2015). Studies of the variations of the first Schumann resonance frequency during the solar flare on 7 March 2012. Journal of Geophysical Research: Atmospheres 120(10), 4600 to 4612. doi:10.1002/2014JD022696
Tereshchenko, E. D., Sidorenko, A. E., Tereshchenko, P. E., Grigoriev, V. F. (2015). Effect of the total solar eclipse of 20 March 2015 on the ELF propagation over high-latitude paths. Geophysical Research Letters 42(17), 6899 to 6905. doi:10.1002/2015GL065255
Space Observing System 70, Tomsk: ELF sonogram and how to read it and seasonal and daily variations (in Russian).
NOAA Space Weather Prediction Center: swpc.noaa.gov