“…In the past 30 years, a number of models and methods have been developed to study the lightning discharge interaction with the lower ionosphere. Different full‐wave theoretical approaches have been used, such as the wave‐hop (ray theory) method (Jacobson et al, , ; Qin et al, ; Shao and Jacobson, ), the waveguide mode theory (Budden, ; Cheng and Cummer, ; Cummer et al, ), or numerical methods such as the Finite‐Difference‐Time‐Domain (FDTD) method (Azadifar et al, ; Han et al, ; Hu and Cummer, ; Marshall, ; Tran et al, ) and the full‐wave Finite Element Method (Lehtinen and Inan, ; Lehtinen and Inan, ). Although empirical models such as the International Reference Ionosphere (IRI) model (Bilitza and Reinisch, ) and the semiempirical FIRI model based on radio wave propagation data from rocket soundings (Friedrich and Torkar, ) could provide the specification of the ionosphere parameters at a given time and location, to simplify the calculation, most VLF remote sensing studies make use of the two‐parameter profile introduced by Wait and Spies () consisting of the reference height and the steepness to infer the ionospheric parameters.…”