Japan Geoscience Union Meeting 2015

Presentation information


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

[P-EM28] Dynamics in magnetosphere and ionosphere

Wed. May 27, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Hiroshi Hasegawa(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), 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)

6:15 PM - 7:30 PM

[PEM28-P11] Observation of heavy ions from the earth's ionosphere in the plasma sheet

*Keisuke NAKAGAWA1, Masafumi HIRAHARA1, Kanako SEKI1 (1.Solar-Terrestrial Environment Laboratory,Nagoya University)

Keywords:magnetosphere, ion outflow, plasma sheet

There are two plasma sources of the plasma sheet in the Earth's magnetotail, i.e., the solar wind and ionospheric outflows. Previous observations have shown that the ionospheric plasma contribution to the plasma sheet depends largely on geomagnetic activities. However, supply mechanism of the ionospheric plasma to the plasma sheet is far from well understood. In order to investigate the fate of ionospheric outflows in the plasma sheet, we have found cold O+ and He+ beams in the plasma sheet at the distance about 20 Re(Earth radii) in the Geotail LEP data from January 1997 to December 2005. The Energy-time spectrograms of the LEP ion data obtained in the plasma sheet show the signatures of cold heavy ion beams outflowing from the ionosphere. Because the mass analysis data of ion with energies less than 10 keV are not available, we identify ion species by velocity distribution function. The plasmas in the plasma sheet are dominated by the E×B drift, therefore the plasma bulk velocities perpendicular to the local magnetic field should be equal in spite of the ion species. We survey the differences of the geomagnetic activities for these ion beams in the plasma sheet. The results show that the intense ion beams are frequently observed when the geomagnetic storms occurred. The energy of these cold heavy ion beams is generally less than 10 keV. In this presentation we discuss these statistical tendencies of the cold heavy ion beams in the plasma sheet.