Description: A technique of solving the inverse problem for the determination of the effective height of the lower ionosphere and the distance to the lightning with tweek-atmospherics - EM signals excited by lightning discharges and observed at night. Wave forms of tweeks were synthesized in the model of the Earth-ionosphere waveguide with an exponential model of the ionosphere conductivity profile. With the help of numerical simulation the errors of estimation of a distance to the lightning and a ionosphere conductivity profile associated with the impact of random noise and the effect of the sphericity of the waveguide were investigated. Predicted error in determining the effective height of the reflection from the ionosphere to the different modes is of of 0.2 - 0.4 km, which allows to evaluate the inverse scale height of the exponential conductivity profile of the lower ionosphere in the range of 0.3 - 0.6 km-1, which are typical values for night conditions.
Keywords: lower ionosphere, ELF-VLF radio waves, tweak-atmospherics Earth-ionosphere waveguide