Properties of Field Aligned Current in Plasma Sheet Boundary Layers in Magnetotail： Cluster Observation

Field aligned current （FAC） distribution in the plasma sheet boundary layers （PSBLs） in the magnetotail is studied statistically by analysing magnetic field data from the Cluster 4-point measurements. The results show that the FAC distribution on the dusk side is not the same as that on the dawn side in the magnetotail. On the each side earthward and tailward, FA C occurrences are different; occurrence and average current density of FA Cs in the northern hemisphere are different from those in the southern hemisphere. This implies that the FACs have dusk-dawn side asymmetry, polarity asymmetry and inter hemisphere difference in the magnetotail. The present results give a good observation evidence for study on the FAC mechanism.

Pc5 Oscillation Analysis by the Satellite and Ground-Based Data

Large amplitude Pc5 event was observed in the space and on ground on August 3, 2001, about three hours after contact of the strong discontinuity in the solar wind with the magnetosphere according to data from ACE and Wind satellites. The Pc5 amplitude was as high as 15 nT in the tail of magnetosphere and about 5 nT at the ground based stations. In the magnetosphere Pc5 waves were observed by Cluster and Polar satellites, which occupied positions in the morning part of the near tail at the close field lines but were parted by distance of 11.5 Re, mainly along the x-axis of the GSM coordinate system. Both compressional and transverse components of the Pc5 wave activity were observed in the space, with the transverse component having the larger amplitude. Time delay between the Cluster and Polar satellites was about 8 minutes, which could be interpreted as a wave propagation from the geomagnetic tail to the Earth with the 150km/s group velocity.The ground-based Pc5 activity was analysed by using data from the Image magnetometer network. Doubtless demonstrations of a field line resonant structure were found in variations of amplitude and polarization with latitude. Finnish chain of search coil magnetometers observed modulated Pc1 emission simultaneously with the Pc5 wave train. A possibility of non-linear impact of Pc5 wave energy on the plasma and waves in the magnetosphere is discussed.

Plasma sheet stretching accompanied by field aligned energetic ion fluxes observed by the NUADU instrument aboard TC-2

NUADU (中立原子察觉者单位) 在 TC-2 上的仪器记录了在 thenear 地球血浆表盘旋在磁场线附近的控告的粒子(E】180 keV ) 的 4nsolid 角度图象(在 ~-7 R_E，赤道的 dawn-to-night 方面) 在地磁气的暴风雨(Dst=-219 nT ) 期间在 2005 年 8 月 24 日。对称的、似环的、稳固的角度分布在周围的磁场线附近描绘的精力充沛的离子横梁事件被 theTC-2 太空船在血浆表的 34-minutetraversal 期间观察。另外，观察被磁强计实验(FGM ) 在一样的太空船上在血浆表的这些多重十字路口期间监视。在每个十字路口期间，口哨声模式合唱团改进被 TC-2 低频率电磁波察觉者(LFEW/TC-2 ) 就在本地更低的混血儿的上面在频率在各向异性的区域观察波浪。离子的比较与这块地里的改进排列了的周围的磁场表演搭角度分发(垫) 地图精力充沛的离子流动被尾巴病房在血浆表拉长磁场线伴随。相反，垂直离子流动改进被在血浆表显示磁场线的相应收缩的签名伴随。因为平行离子流动和垂直离子流动改进间歇地发生了，数据被解释暗示磁场线的一个动态、摆动的过程(拉长并且缩小)在thenear地球血浆表，它可能行动了帮助在将支持在进行中的磁性的暴风雨期间被触发的连续 aurora-substorm 的这个区域建立一个相互作用区域。Thewhistler 模式合唱团可能在血浆表压缩以后在粒子沥青角度散开期间由于离子旋转罗盘回声被生产了。