Numerical Modeling of the Concentric Gravity Wave Seeding of Low-Latitude Nighttime Medium-Scale Traveling Ionospheric Disturbances

The first-principles three-dimensional ionosphere model Naval Research Laboratory SAMI3/ESF is used to study the low-latitude nighttime medium-scale traveling ionospheric disturbances (MSTIDs) triggered by the typhoon-induced concentric gravity waves (CGWs) for the first time. Simulation results demonstrate that the electrodynamic coupling between CGWs and Perkins instability can initiate the rarely observed low-latitude nighttime MSTIDs by accelerating their growth rates. Both the simulations and observations show that the westward and westward/equatorward propagating CGWs with similar wavefront alignments to the Perkins instability could enhance the generation of MSTIDs rather than the northward propagating CGWs. The CGWs penetrating to the ionospheric F layer without severe dissipation can induce greater polarization electric fields to accelerate the Perkins instability via E × B drifts.