[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P17] Study of Nighttime Mid-latitude E-F Coupling in Geomagnetic Conjugate Regions Using a Double-thin-shell Model and Multi-source Data

*傅 維正¹、横山 竜宏¹、セサンガ ニコラス²、馬 冠一³、山本 衛¹ (1.京都大学生存圏研究所、2.オスロ大学、3.中国科学院国家天文台)

キーワード：中規模伝搬性電離圏擾乱、衛星測位システム-TEC、E-F カップリング

Geomagnetic conjugate mid-latitude nighttime ionospheres are frequently simultaneously populated with electrified nighttime medium-scale traveling ionospheric disturbances (MSTIDs). Earlier observations and theoretical analysis have underscored the ionosphere E-F coupling and the postulation of coupled conjugate hemispheres, playing a pivotal role in the formation of electrified MSTIDs. In this paper, the conjugate MSTIDs are studied to elucidate the causes and effects of E-F coupling in the interhemispheric coupled ionosphere. The hemisphere-coupled ionospheres over Japan and Australia are observed and analyzed using total electron content (TEC) measurements, supplemented with multi-source observations from ionosondes, ICON (neutral wind), COSMIC (electron density) and Swarm (magnetic field). A double-thin-shell model is introduced to analyze the ionospheric responses in E and F regions during the coupling process. For the first time, observation results provide the evidence that F-region geomagnetic conjugate irregularities in both hemispheres are mainly driven by the Es layers in the summer hemisphere. The Es layer in the summer hemisphere subsequently triggers local E-F coupling and inter-hemispheric coupling. In the winter hemisphere, Es layers show amplitude reduction or even dissipation during the interhemispheric coupling process. Furthermore, thermospheric winds and non-equipotential magnetic field lines are presumed candidates for the inter-hemispheric asymmetry in MSTIDs amplitudes and growth rates.