Japan Geoscience Union Meeting 2014

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Symbol P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM28_29PM1] Magnetosphere-Ionosphere Coupling

Tue. Apr 29, 2014 2:15 PM - 4:00 PM 413 (4F)

Convener:*Shin'ya Nakano(The Institute of Statistical Mathematics), Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Nagoya University Solar Terrestrial Environment Laboratory Geospace Research Center), Chair:Shin'ya Nakano(The Institute of Statistical Mathematics), Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Nagoya University Solar Terrestrial Environment Laboratory Geospace Research Center)

2:30 PM - 2:45 PM

[PEM28-08] Characteristics of Pi 2 pulsations around the dawn and dusk terminator

*Shun IMAJO1, Akimasa YOSHIKAWA2, Teiji UOZUMI2, Shinichi OHTANI3, Aoi NAKAMIZO4, Richard MARSHALL5, Boris M. SHEVTSOV6, Victor A. AKULICHEV7, Usnikh SUKHBAATAR8, Kiyohumi YUMOTO2 (1.Dept. Earth Planet. Sci., Kyushu Univ., 2.ICSWSE, Kyushu Univ., 3.APL, Johns Hopkins Univ., 4.FMI, Arctic Research Unit, 5.IPS Radio and Space Services, Bureau of Meteorology, Australia, 6.Institute of Cosmophysical Researches and Radio Wave Propagation, 7.Pacific Oceanological Insititude, FEB RAS, 8.The Research Center of Astronomy and Geophysics of Mongolian Academy of Sciences)

Keywords:Pi 2 pulsations, The dawn and dusk terminator, Ionospheric currents, FACs

We statistically investigate low-latitude Pi 2 pulsations observed around the dawn and dusk terminator. The main observational results of this study are: (1) Pi 2 pulsations tended to have east-west polarity in the sunlit side of the dawn terminator, while these in the sunlit side of the dusk terminator tended to have north-south polarity. (2) Phase reversals of D-component oscillations occurred near the dawn terminator and 2-3 hours before the dusk terminator. (3) Peaks of D/H (maximum amplitude ratio between D and H component) appear 3 hours after the dawn terminator and near the dusk terminator.We suggest that there is the dawn-dusk asymmetry of meridional ionospheric currents connecting between equatorial Cowling current and oscillating nightside FACs; meridional currents around dawn is more intense than around dusk. This asymmetry current system can be qualitatively explained by the deformation of potential pattern caused by polarization charges at the terminator.