磁层顶高纬边界层的瞬时重联过程

TRANSIENT MAGNETIC RECONNECTION PROCESSES AT THE HIGH LATITUDE BOUNDARY LAYER

用二维可压缩的ＭＨＤ模型模拟研究了北半球背阳面磁层顶区的瞬时重联过程．结果表明，当行星际磁场（ＩＭＦ）具有南向Ｂｚ分量和背太阳向Ｂｘ分量时，ＩＭＦ与地磁场联接，磁层顶向外扩张，在等离子体幔区可形成流体旋涡，磁力线被扭曲，但不易形成磁涡旋；当ＩＭＦ具有北向Ｂｚ分量时，不论Ｂｘ分量是背向太阳或指向太阳，都可发生瞬时重联，而且当ＩＭＦＢｘ分量与地磁场Ｂｘ分量反向时，在等离子体幔区更易形成磁涡旋．这两种情况，在磁层顶边界层区都能产生多层的电流片．

By using a two-dimentional compressible MHD model,the transient magnetic reconnection processes at the nightside magnetopause boundary layer are simulated based on the theary of vortex-induced reconnection.It is found that when the IMFhas a southward Bz,the IMF connects with the geomagnetic field at the nightsidenorthern magnetopause only When the IMF Bx component is opposite to the sun worddirectioon.In this case the magnetopuse moves toward the magnetotheath region;no magnetic vortices are formed in the magnetopause boundary layer.When theIMF has a northward Bz and Bx, sunward Bx, the transient reconnection may occurat the nightside magnetopause region; and fluid vortices and magnetic vortices are also formed.