作者: B. Hu , R. A. Wolf , F. R. Toffoletto , J. Yang , J. Raeder
DOI: 10.1029/2011JA016667
关键词: Substorm 、 Magnetohydrodynamics 、 Classical mechanics 、 Magnetic reconnection 、 Convection 、 Mechanics 、 Instability 、 Physics 、 Field line 、 Magnetic field 、 Current sheet
摘要: [1] It is widely believed that during a substorm, plasma instabilities occur before the onset of magnetic reconnection, signaling end growth phase. Despite many years effort, however, details how instability and reconnection develop from closed field line configuration with finite normal are not well understood. In this paper, we study an idealized simulation substorm occurred on 23 March 2007, based Open Geospace General Circulation Model (OpenGGCM). Our analysis emphasizes time development distribution entropy parameter its convective derivative, which should be zero in ideal MHD. late phase, exhibits, over range local times, systematic violation conservation corresponds to what called “antidiffusion.” Out background, more localized disturbance develops region high stretching, resulting formation strong reduction (bubble) earthward enhancement (blob). The process accelerated when current density exceeds threshold for triggering explicit resistivity code. bubble moves blob tailward, leads thinning sheet between them, making magnetospheric conducive tearing other (we do address specifically has occurred). This positive feedback gives rise increased perfect conductivity relation eventually reconnection.