[P-EM15] Dynamics of Magnetosphere and Ionosphere

[PEM15-P05] Seasonal and North-South Hemispheric Asymmetry of Dayside Pi2 Pulsations at Low Latitudes

*上田 陽彦¹、今城 峻² (1.京都大学、2.京都大学大学院理学研究科附属地磁気世界資料解析センター )

キーワード：Pi2地磁気脈動、電離圏電流

Although dayside Pi2 pulsations are considered to be generated by ionospheric currents, the effect of ionospheric conductivity variations have not been understood. To clarify this effect, we statistically analyzed ~2000 Pi2 events from observed at Kakioka (KAK) in Japan (Northern Hemisphere) and Charters Towers (CTA) in Australia (Southern Hemisphere) over a three-year period from 2012 to 2014. For the selected events, the H and D amplitudes were calculated,and the mean and median values of these quantities were obtained for each month and each local time. The D amplitude and D/H amplitude ratio near the dawn terminator started to increase from earlier local times in the summer hemisphere, while those near the dusk terminator started to increase from earlier local times in the winter hemisphere. These characteristics can be explained by the opposite sense deflection of the ionospheric current on the day side and the field-aligned currents on the night side. Also, the H amplitude on the dayside is larger in the summer hemisphere than in the winter hemisphere. The present results suggest that seasonal variation of conductivity affect on seasnal variation of characristics of dayside Pi2.