This model shows that about an hour after the tsunami takes place, the ionosphere will be perturbed via the gravity wave. The height with maximum perturbation of electron number density is near 300 km, which is also the altitude of maximum background electron density. The propagation constant of the gravity wave is determined by the atmospheric property. Taking the tsunami wave as boundary condition, the dispersive atmosphere with dissipation will modulate the tsunami wavefrom as it reaches the ionospheric height. A more complete two-dimensional model is proposed to estimate the disturbance in the atmosphere and ionosphere caused by tsunami. This model contains the source of IGWs, hence can differentiate between other atmospheric TID signals in the ionosphere. The IGWs are modeled up to 800 km in waveform, amplification, and propagation time. The interaction between ionospheric plasma and the neutral air is also considered.