Equatorial ionospheric bubble precursor

A time‐dependent nonlinear three‐dimensional model for the evolution of the equatorial bottomside lower ionosphere in the presence of dissipating gravity waves has been developed. From the numerical solution of the model, it is found that large bottomtype F‐region ionospheric density perturbations and electric fields can be driven by dissipating gravity waves from tropospheric sources. The spatial distribution of the ionospheric F‐region density perturbations can be characterized as a patchy, layer‐like structure and may be responsible, in part, for observed large scale wavelike structures in the equatorial bottomside F‐region which are a precursor to fully developed equatorial ionospheric bubbles. Favorable comparison of the model with observations is made.