TC-1卫星在近地磁尾观测到的持续尾向流、等离子体片变薄和偶极化过程

2004年7月14日TC-1卫星在近地磁尾(-9.3Re,-5.4Re,1.2Re)附近观测到了伴随有持续尾向流的等离体片变薄和偶极化过程.尾向流持续时间为32分钟.偶极化过程中磁场By分量没有明显变化.在偶极化过程发生两分钟之后，地面台站观测到的Pi2脉动.ACE卫星的观测表明行星际磁场有弱的南向行星际磁场（-2nT），持续时间约55分钟.Imagine卫星在电离层区域没有观测到极光出现.和伴随有极光增亮的亚暴过程相比，南向行星际磁场明显较弱，且持续时间短.TC-1卫星和ACE卫星的联合观测表明尾部释能有大有小，并非达到某值才能发生.但能量小时，不能够引起极光亚暴.其次南向行星际磁场有可能与近地磁尾尾向流有密切关系.

Tailward flow, plasma sheet thinning and dipolarization observed by TC-1 satellite

TC-1 satellite observed the plasma sheet thinning, dipolarization process along with the continuous tailward flow in the near-Earth magnetotail around (-9.3Re,-5.4Re,1.2Re) on Jul 14, 2004. The duration of the tailward flow is about 32 min. The By component of magnetic field remains nearly unchanged during the magnetotail dipolarization. Pi2 pulsations are detected by ground stations in 2 min late after the dipolarization. The ACE satellite observation indicated that a continuously weak southward IMF (~-2nT) persists about 55min. There is no aurora brightening observed by Imagine satellite in the ionosphere. The joint exploration of the TC-1 and the ACE satellites suggests that the auroral substorm occur only when the energy release of the magnetotail substorm exceeds a certain threshold. The By component of magnetic field may have a close relation with the auroral substorm.