根据太阳活动最小时期的观测日冕形状的长期变化
Secular variations in the solar corona shape according to observations during a solar activity minimum epoch
摘要：
分析了1867年至2006年太阳活动最小期的日冕结构。本文提出了一个新的大冕流压扁指数。结果表明，该指数在过去140年中一直在平稳变化。该指数的最小值出现在活动周期17- 19;这是太阳日冕最对应于太阳全球磁场的偶极配置的时期。在20世纪初和21世纪初，日冕结构对应于四极结构。讨论了日冕结构变化的原因及其与地磁活动的关系。
英文摘要：
Analysis of the solar corona structure during the periods of minimum solar activity from 1867 till 2006 has been carried out. A new flattening index for the large coronal streamers has been proposed. It has been shown that the index has been smoothly changing during the last 140 years. The minimal value of the index occurred during activity cycles 17--19; this was the period when the solar corona most of all corresponded to the dipole configuration of the global magnetic field of the Sun. At the beginning of the 20th and the 21st centuries, the corona structure corresponded to the quadrupole configuration. The reasons for the variations in the solar corona structure and its relation to geomagnetic activity are discussed.
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