The Formation and Maintenance of the Dominant Southern Polar Crown Cavity of Cycle 24
The Formation and Maintenance of the Dominant Southern Polar Crown Cavity of Cycle 24
复制标题
第24旋回南极地冠空洞的形成与维持
DOI：
10.3847/1538-4357/835/2/135
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
W. Pesnell
中科院分区：
文献类型：
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作者：
N. Karna;J. Zhang;W. Pesnell
在这篇文章中，我们报告了一项研究，利用2013年的观测结果，研究了太阳周期24中寿命最长的极地冠洞，并提出了一种解释其持续存在的物理机制。我们利用太阳动力学观测台（SDO）上的大气成像组件（AIA）和日震磁成像仪（HMI）的高时空分辨率观测资料，对空腔的结构和演化进行了探索。虽然它存在了一年多，但我们从2013年3月21日到2013年10月31日对环极空腔进行了详细的研究。我们的研究强化了现有的极性冠细丝形成理论，该理论涉及形成任何极性冠空腔的两个基本过程，以及我们在这里研究的长寿命空腔。首先，在(1)分布在不同经度的数十个衰减活动区的尾部与(2)极日冕洞内的单极磁场之间形成环极空腔的下伏极性反转线（PIL）。其次，腔体的长寿命是由沿PIL的持续磁通抵消维持的。通量通过地面经向流动和扩散持续向极区输送。持续的通量抵消导致极日冕空洞的缩小。
In this article, we report a study of the longest-lived polar crown cavity of Solar Cycle 24, using an observation from 2013, and propose a physical mechanism to explain its sustained existence. We used high temporal and spatial resolution observations from the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager (HMI) instruments on board the Solar Dynamics Observatory (SDO) to explore the structure and evolution of the cavity. Although it existed for more than a year, we examined the circumpolar cavity in great detail from 2013 March 21 to 2013 October 31. Our study reinforces the existing theory of formation of polar crown filaments that involves two basic processes to form any polar crown cavity as well as the long-lived cavity that we studied here. First, the underlying polarity inversion line (PIL) of the circumpolar cavity is formed between (1) the trailing part of dozens of decayed active regions distributed in different longitudes and (2) the unipolar magnetic field in the polar coronal hole. Second, the long life of the cavity is sustained by the continuing flux cancellation along the PIL. The flux is persistently transported toward the polar region through surface meridional flow and diffusion. The continuing flux cancellation leads to the shrinking of the polar coronal hole.