arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1807.01617astro-ph.SR
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预测太阳偶极矩需要多少个活动区?

How many active regions are necessary to predict the solar dipole moment?

T. Whitbread, A. R. Yeates, A. Muñoz-Jaramillo

摘要:

我们测试了最近的说法,即在第23个周期结束时,极场被少数大的,异常取向的区域削弱,并调查这对太阳周期预测意味着什么。我们使用二维表面通量输运模型从第21、22和23周期的磁图中分离出各个区域的贡献,发现虽然前10%的贡献者倾向于定义轴向偶极矩的突然大变化,但许多较弱区域的累积贡献不能忽略。为了在合理的程度上重建轴向偶极矩,当按贡献排序时,在周期23中需要比在周期21和22中更多的区域。我们认为,第23周最重要区域的负贡献确实可能是导致下一个周期最小值和低振幅周期24的弱极场的原因。我们还研究了一个地区的轴向偶极矩的贡献和它的出现纬度,通量和初始轴向偶极矩之间的关系。我们发现,一旦一个给定的区域的初始偶极矩已被测量,我们可以预测的长期偶极矩的贡献单独使用出现纬度。

英文摘要:

We test recent claims that the polar field at the end of Cycle 23 was weakened by a small number of large, abnormally oriented regions, and investigate what this means for solar cycle prediction. We isolate the contribution of individual regions from magnetograms for Cycles 21, 22 and 23 using a 2D surface flux transport model, and find that although the top ~10% of contributors tend to define sudden large variations in the axial dipole moment, the cumulative contribution of many weaker regions cannot be ignored. In order to recreate the axial dipole moment to a reasonable degree, many more regions are required in Cycle 23 than in Cycles 21 and 22 when ordered by contribution. We suggest that the negative contribution of the most significant regions of Cycle 23 could indeed be a cause of the weak polar field at the following cycle minimum and the low-amplitude Cycle 24. We also examine the relationship between a region's axial dipole moment contribution and its emergence latitude, flux, and initial axial dipole moment. We find that once the initial dipole moment of a given region has been measured, we can predict the long-term dipole moment contribution using emergence latitude alone.

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