无力场模型黑子上空的纵向磁场梯度

本文按常α无力场模型计算了1980年10月23日Boulder 2744活动区前导黑子的纵向磁场随高度的变化,并与用CIV 1548谱线观测得到的色球一日冕过渡区的磁场资料相结合,求得CIV 1548发射区的有效高度。这些结果与文献4]中对同一黑子用势场模型推求的结果有很大差别。从而表明,势场和无力场在某些方面导致的结果是极不相同的。鉴于观测已表明活动区上空存在电流的事实,在活动区磁场的模拟中,特别是在强扭曲活动区磁场的计算中,应当避免采用势场,而尽可能采用无力场模型。

The Vertical Gradient of Sunspot Magnetic Fields Based on a Force-Free Field Model

The vertical gradient of the longitudinal magnetic field above the preceeding sunspoc of the active region Boulder 2744 on 23 October, 1980 was calculated based on the model of constant a force-free field. In connection with the longitudinal magnetic field of the chromsphere-co-I'ona transition region observed in the spectral line CIV 1548, the effective height of the CIV 1548 emission region was estimated. These results are quite different from those obtained in-reference 4] for the same active region based on a. model of a potential magnetic field. This shows that adoption of a model of a potential field or a model of a force-free field will lead to very different results in some cases. Considering the fact that observations have revealed that there are electric currents above active regions, it is advisable to adopt a model of a force-free field instead of a model of a potential field, if possible, in calculating the magnetic field of an active region, particularly in a region with a highly twisting field.