Separator reconnection with antiparallel/component features observed in magnetotail plasmas

Abstract

Magnetic reconnection (MR), a fundamental process in space plasmas that changes magnetic topology and converts magnetic energy into kinetic and thermal energies, is an ultimate driver of space weather. There exist two models of MR in the literatures, antiparallel and component, associated with intensive studies of their generation and applications. In this paper, we report an MR event observed by Cluster constellation in the geomagnetotail where both types of MR were detected. By reconstructing the three-dimensional (3-D) MR configuration, we find that a pair of A-B nulls existed in both types of MR cases with two fan surfaces intersecting each other to form a separator line connecting the nulls. A weak or sizable magnetic field exists along the separator in the antiparallel or component case, respectively. In the latter case, field strength is finite away from the two nulls and vanishes close to the nulls. Therefore, at least in the two cases observed, both antiparallel and component MR geometries are local presentation of the separator MR configuration. This result supports the expectation that 3-D nulls often occur as a crucial element of MR at least in the magnetotail and separator MR may play an important role in dynamics and reconfiguration of magnetic field in 3-D MR processes. Key Points Anti-parallel and component reconnection are separator reconnection ©2013. American Geophysical Union. All Rights Reserved.