[P-EM13] Coupling Processes in the Atmosphere-Ionosphere System

[PEM13-03] Numerical studies on 3D dynamics of the sporadic E layers at the geomagnetic mid-latitudes

★Invited Papers

*Satoshi Andoh¹, Akinori Saito¹, Hiroyuki Shinagawa², Mitsumu K. Ejiri^3,4 (1.Graduate School of Science, Kyoto University, 2.National Institute of Information and Communications Technology, 3.National Institute of Polar Research, 4.SOKENDAI, the Graduate University for Advanced Studies)

Keywords:Sporadic E, Ionosphere, Simulation

A 3D ionospheric model has been developed to elucidate 3D dynamics of the sporadic E layers (EsLs) at the geomagnetic mid-latitudes. The EsLs are highly dense plasma layers, appearing in the ionospheric E region. They consist mainly of metal ions such as Fe⁺, Mg⁺ and Ca⁺. The wind shear theory is widely accepted as the EsL formation mechanism. According to the theory, the EsLs are formed by the vertical shears of the horizontal winds. This theory can explain vertical dynamics of the EsLs, but not horizontal dynamics. Till now, it has been unclear how the EsLs evolve horizontally and how the horizontal Es dynamics is observed by the traditional 1D observations such ionosondes, radars, and lidars. Recently, we developed a 3D ionospheric numerical model coupled with the realistic neutral winds of a whole atmospheric model. The numerical model generally succeeded in reproducing the day-to-day variations of the EsLs around Japan and Arecibo. Moreover, our 3D ionospheric model revealed the 3D EsL dynamics. For example, the EsLs lag behind the wind shear nodes as descending due to the frequent ion-neutral collisions; the local time dependence of the horizontal EsL movements differs between descending and stagnating EsLs. In this presentation, we will review our recent studies of the 3D EsL dynamics and morphology using the newly developed 3D ionospheric model. Physical mechanisms of the day-to-day variations and horizontal movements of the EsLs will be discussed.