Applicability of a double-layer model for description of three-dimensional evolution of a strong ionospheric inhomogeneity

Possibility of using Lloid and Herendel double layer model for adequate description of a strong ionospheric inhomogeneity dynamics have been analysed. Three-dimensional simulation of evolution of large-scale nonlinear cloud in a strong external electrical field, taking account of the background plasma redistribution due to polarization field, is carried out. The highest dependences of the background plasma concentration and mobility coefficients are accepted complying with the real ionosphere. It is shown that ionospheric disturbances due to the cloud elolution at different heights are not similar. Yet, the cloud drift and deformation, calculated for a three-dimensional case, well agree with the calculations in a double-layer approximation, i.e. when the whole ionospheric conducting width is characterized by constant averaged with respect to height parameters