Vortex flows in the solar chromosphere - I. Automatic detection method
Vortex flows in the solar chromosphere - I. Automatic detection method
复制标题
太阳色球层的涡流——一、自动检测方法
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
S. Wedemeyer
中科院分区：
文献类型：
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作者：
Y. Kato;S. Wedemeyer
太阳“磁龙卷风”是由从上层对流区和光球层延伸到日冕的旋转磁场结构产生的。最近的研究表明，这类旋转特征是大气动力学的一个组成部分，并且发生在大范围的空间尺度上。对磁龙卷风进行系统的统计研究是了解其形成及其在太阳大气中质量和能量传输中的作用的必要的下一步。为此，我们开发了一种新的自动检测方法的色球漩涡，这意味着可观察到的太阳龙卷风的签名，或更一般地说，色球涡流和旋转运动。与现有的依赖于目视检查的研究不同，我们的新方法结合了线积分卷积（LIC）成像技术和代表二维平面上涡流的标量。我们已经测试了两种检测算法，增强涡度和涡度强度量的基础上，通过将它们应用到三维数值模拟的太阳大气CO5BOLD。结果表明，涡量强度法在各方面都上级增强涡量法。应用该方法对太阳大气的数值模拟揭示了非常丰富的小尺度，短暂的色球涡旋流，没有发现以前的目视检查。
Solar “magnetic tornadoes” are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.