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.