[P-EM13] Dynamics of Magnetosphere and Ionosphere

[PEM13-16] Statistical characteristics of the duskside mesoscale field-aligned currents without accompanying the large-scale Region 1 current

*横山 佳弘¹、田口 聡¹、家森 俊彦²、細川 敬祐³ (1.京都大学大学院理学研究科地球惑星科学専攻地球物理学教室、2.京都大学、3.電気通信大学大学院情報理工学研究科)

キーワード：メソスケール沿磁力線電流、北向きIMF、Swarm衛星

During prolonged quiet times the large-scale Region 1 current nearly diminishes except for its near-noon part, and irregular magnetic perturbations exist at latitudes where the Region 1 current disappeared. Our recent event study has shown that the irregular magnetic perturbations on the duskside are a result of highly structured quasi-static field-aligned currents whose typical latitudinal size is 20–30 km, and that those mesoscale currents in the duskside auroral oval are the phenomena that are pertinent to the magnetosphere for a northward IMF condition, not a simple remnant of the typical Region 1. In the present study, in order to clarify detailed characteristics of the mesoscale field-aligned currents without accompanying the large-scale Region 1 we examined large amounts of data obtained by Swarm satellites during three years, i.e., from January 2014 to December 2016. How the occurrence of those mesoscale field-aligned currents is controlled by solar illumination of the ionosphere and upstream solar wind parameters other than the northward component of IMF is presented.