Two Approaches for Modeling ELF Wave Propagation in the Earth-Ionosphere Cavity With Day-Night Asymmetry

In this article, we introduce a lesser-known analytical treatment and a new numerical approach to model electromagnetic wave propagation in the lowest part of the extremely low-frequency (ELF) band (<; 100 Hz) that takes into consideration the day-night asymmetry of the Earth-ionosphere cavity. We present numerical tests showing that the two models produce practically the same output, i.e., the relative difference between them is less than 0.4%. Our result is an important step toward inferring the distribution and intensity of global lightning activity based on the Schumann resonance (SR) measurements, which is the main objective of our work.