HR: 1340h
AN: SM43A-1075    [Abstracts]
TI: Magnetic Structures with Rich Ionospheric Oxygen Ions Observed in the near Earth Plasmasheet
AU: * Fu, S
EM: suiyanfu@pku.edu.cn
AF: ISPAT, Peking University, Beijing, 100871, China
AU: Zong, Q
EM: qgzong@gmail.com
AF: Center for Atmospheric Research, University of Massachusetts Lowell, Lowell, 01854-3629, United States
AU: Pu, Z
EM: zypu@pku.edu.cn
AF: ISPAT, Peking University, Beijing, 100871, China
AU: Korth, A
EM: korth@mps.mpg.de
AF: Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, Ketlenburg- Lindau, 37191, Germany
AU: Daly, P
EM: daly@mps.mpg.de
AF: Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, Ketlenburg- Lindau, 37191, Germany
AB: Magnetic structures with predominant ionospheric O+ ions have been observed on November 8, 2004 by the Cluster and Double Star spacecraft during a strong magnetic storm time period. The oxygen densities in two BBFs are found to be 3-5 times larger than the hydrogen densities and the oxygen thermal pressures in the BBFs are 8 times larger than the hydrogen thermal pressure. Moreover, the dynamic ram pressure of the oxygen BBFs is 16 times larger than a normal BBF moving in the same speed and it is inferred that the braking region should be greatly pushed inside the usual pressure balance region when the BBF is dominated by oxygen ions. It is found that in the earthward flowing plasmoid, oxygen ions are relatively cold with a higher kinetic pressure than thermal pressure inside the structure. It is therefore suggested that oxygen ions in the tailward flowing plasmoid might be heated in the near earth current sheet. The observations made in this paper suggest that singly charged oxygen ions embedded in the BBFs may be carried into the inner region during very intense magnetic storms. The Cluster - Double Star constellation offers a good opportunity to ascertain the evolutional signatures of fast moving plasma flow in the near Earth region.
DE: 2764 Plasma sheet
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting