Simulation of horizontal sporadic E layer movement driven by atmospheric tides

The present study aims to reveal horizontal sporadic E (Es) movements driven by atmospheric diurnal/semi-diurnal tides using a three-dimensional (3D) ionospheric model. Horizontal Es movements have been investigated since the mid-twentieth century, using a variety of 1D/2D observational techniques. However, there are no comprehensive studies that explain the different results asserted by the observations. Herein, we performed 3D Es simulations at mid-and low-latitudes. This is the first study to investigate horizontal Es movements from a 3D perspective. We found that the Es layers are constrained at the zonal-wind shear nodes above similar to 110 km, but transported by horizontal winds below similar to 110 km. The Es layers that descend with the downward tidal phases move southward. The descending Es layers move westward as they lag behind the zonal-wind shear nodes. The Es layers that stagnate at similar to 100 km are transported by the semi-diurnal tides. In general, the descending and stagnating Es layers do not move eastward. This is because the Es layers diffuse vertically in the eastward/northward wind region or in the early stage of formation in the eastward/southward wind region. The horizontal Es movement tendency in the simulations agreed with and provided a general explanation for previous observations.