Mapping ionospheric convection patterns to the magnetosphere
Mapping ionospheric convection patterns to the magnetosphere
复制标题
将电离层对流模式映射到磁层
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
W. J. Burke
中科院分区：
文献类型：
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作者：
N. Maynard;W. Denig;W. J. Burke
高纬度电离层的对流模式通常是在共转参照系中呈现的，而磁层的对流模式则是在惯性坐标中呈现的。在共转表示的对流喉道，这是经常与尖点，打开之间1000和1100 MLT。然而，尖点降水集中在中午左右。我们发现将Heppner和Maynard（1987）（以下简称H-M）的对流模式转换到惯性坐标系中，喉道区与当地正午一致。我们利用Tsyganenko（1989）的磁场模型，在共转和惯性坐标系中给出了H-M模式到磁层的投影。在惯性坐标系中，映射的H-M对流喉道在中午打开。与赖斯对流模型预测的磁层电场晚在亚暴周期一致，只有一小部分的等势线穿透到太阳下区域。这表明，一个显着的部分磁通管合并发生在磁场线的赤道映射是两侧的磁层。正行星际磁场BY和负行星际磁场BY的H-M图之间的非共轭性，特别是在1400-1600 LT扇区，可以解释Evans（1985）发现的电子沉淀“热点”对BY的依赖性。一个单独的叶细胞是不需要解释的中心，等位线的大对流单体。
While convection patterns in the high-latitude ionosphere are usually presented in a corotating frame of reference, those of the magnetosphere are given in inertial coordinates. In the corotating representation the convection throat, which is frequently associated with the cusp, opens between 1000 and 1100 MLT. Cusp precipitation, however, centers about noon. We find that transforming the convection patterns of Heppner and Maynard (1987) (hereinafter H-M) into inertial coordinates aligns the throat region with local noon. We present projections of the H-M patterns to the magnetosphere in both corotating and inertial coordinates using the magnetic field model of Tsyganenko (1989). In inertial coordinates the mapped H-M convection throat opens at noon. Consistent with predictions of the Rice convection model for magnetospheric electric fields late in the substorm cycle, only a small fraction of the equipotential contours penetrate to the subsolar region. This suggests that a significant portion of flux tube merging occurs on magnetic field lines whose equatorial mapping is on the flanks of the magnetosphere. Nonconjugacy between the mapping of H-M patterns for both positive and negative interplanetary magnetic field BY, especially in the 1400-1600 LT sector, may explain the BY dependence of the electron precipitation “hot spot” discovered by Evans (1985). A separate lobe cell is not required to explain the central, equipotential contours of the large convection cell.