Schumann Resonance“…resonance is the tendency of a system to oscillate with greater amplitude at some frequencies than at others. Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies, or resonance frequencies. At these frequencies, even small periodic driving forces can produce large amplitude oscillations, because the system stores vibrational energy…Some systems have multiple, distinct, resonant frequencies…” – Wikipedia• Schumann resonances (SR) are standing electromagnetic waves in the Earth-Ionosphere waveguide spanning the

extremely low frequency spectrum (3-60 Hz) – a portion of the spectrum where lightning return strokes emit appreciable energy.

• Schumann (1952) developed a theoretical prediction for the supported frequencies which was subsequently refined (1954, 1957) to account for imperfect conductivity in the concentric spherical cavity and inhomogeneous electron density in the ionosphere along the propagation path.

𝜈𝑛=𝑐2𝜋 𝑎 √𝑛(𝑛+1)𝑛=1,2,3 ,…

ν1~10.6 Hz, ν2~18.35 Hz, ν3~25.96 Hz, … (Schumann 1952)

• The phenomenon was first measured by Schumann and Kӧnig (1954) and Balser and Wagner (1960) later identified the first 5 modes (νn = 7.8, 14, 20, 26, and 33 Hz).

Balser and Wagner (1960)

NEW ENGLAND, USA

How Can We Use SR?SE POLAND

**SR MODE OBSERVATIONS GLOBALLY VERIFIED

Nieckarz et al. (2009)

1. Fit a curve to hourly observations of power spectrum of ELF E/B fields.

2. Sum the coefficients for each mode to generate a “lightning activity index”

AFRICA13 UTC

M.C.8 UTC

AMERICA20 UTC

3. Diagnose the direction to sources using quantitative estimates of electric/magnetic field amplitude and knowledge of precise orientation of observation apparatus.

**MONITOR THE GLOBAL ELECTRICAL HEART BEAT**

In The Context of the Williams AGU Lecture…

GLOBAL INCREASE IN T

AMPLIFIED SR RESPONSE

INCREASE IN CAPE

MORE INTENSE T-STORMS

Documented in some places, yet not everywhere (sources?)…

Will the vertical temperature structure respond in such a way to favor more instability (e.g. warming the surface/cooling aloft)? Are there other possible warming scenarios?

What exactly constitutes a “more intense thunderstorm”?Higher flash rates? Similar flash rates but more energetic individual flashes? How will the microphysics of charge separation respond to changes in the temperature profile?

If the thunderstorm activity (flash rate/energy) changes significantly in response to the changing global climate, will the electrical activity continue to efficiently excite the SR modes? Will monitoring SR continue to be a viable proxy for global lightning activity?

Random Radio Noise of Balser and Wagner (1960)

Some studies have documented a year to year consistency in the Schumann Resonances at individual locations.

Satori and Zieger (1996)