大型太阳活动区磁场的一个模型

用时间缓变的非线性无力场模拟超级活动区（弧岛式大型δ黑子）的磁场位形。这个复杂磁场包含了向量磁场的主要观测特征：正负磁流极端不平衡性（正负磁流之比为１：６），Ｕ形磁反变线，局域磁场的二极子、四极子差异性。模拟结果厅用来解释一些观测结果：（１）大耀斑主要产生在Ｕ形中性线的磁性混杂区或四极子区（２）Ｕ形反变线的准双极性区几乎没有大耀斑很小。（３）活动区内部的大型旋转运动和磁沲运动会导致四极子场磁拓扑分

A MODEL OF MAGNETIC FIELDS IN A SUPER SOLAR ACTIVE REGION

Within the framework of nonlinear force free fields, the authors try to model the magnetic field configurations of a super active region (with large island sunspots). They choose to represent the magnetic fields in terms of Eulerian potential variables and employ Woodsbury's relaxation method. This complicated magnetic field model includes the main characteristics of observed vector magnetic field of a super active region: i.e. the large magnetic flux imbalance, the U shaped inversion line and the difference between bipolar and quadrupolar magnetic fields. This model enables us to understand the following phenomena: (1) Major flares often occur near the U shaped inversion line where the magnetic filed configurations are qradrupolar. (2) No major flares occur near the U shaped inversion line where the magnetic field configurations are quasi bipolar. (3) Under large scale rotational motion and flux emergence the separatrix in a quadrupole can produce a large current sheet where strong magnetic reconnection takes place.