Schumann resonance spectra in a two-scale-height Earth-ionosphere cavity

New expressions are developed for the amplitude and power spectra of the electric and magnetic components of lightning-excited Schumann resonances. A classical normal mode approach is used, yielding expressions directly in terms of the complex eigenfrequencies of the Earth-ionosphere cavity. Using previous simplified formulations of the eigenvalue problem in terms of a two-scale-height model of a dissipative Earth-ionospheric cavity, these results permit calculation of spectra in terms of geometric properties of the system. The expressions are in a convenient form for application in correlation studies involving use of the resonance intensities as a proxy measure of other Earth system parameters, such as average tropical continental temperature [Williams, 1992].