TURBULENT DIFFUSION IN THE PHOTOSPHERE AS DERIVED FROM PHOTOSPHERIC BRIGHT POINT MOTION
TURBULENT DIFFUSION IN THE PHOTOSPHERE AS DERIVED FROM PHOTOSPHERIC BRIGHT POINT MOTION
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光球亮点运动引起的光球中的湍流扩散
DOI：
10.1088/0004-637x/743/2/133
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Abramenko V
中科院分区：
文献类型：
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作者：
Abramenko V
根据大熊太阳天文台新太阳望远镜对太阳颗粒化的观测结果，探讨了太阳宁静区、冕洞和活动区斑中亮点的自行。我们自动检测和跟踪BP，并推导出它们的均方位移作为时间的函数（从每个BP的出现开始）为所有可用的时间间隔。在所有三种磁环境中，我们发现了超扩散制度的存在，这是最明显的时间间隔内的10 - 300秒。超扩散，通过光谱指数γ来测量，γ是均方位移光谱的斜率，从斑区（γ = 1.48）到宁静太阳区（γ = 1.53）再到冕洞（γ = 1.67），超扩散逐渐增加。我们还发现，湍流扩散系数的变化与时间和空间尺度成正比。对于最小空间尺度（22 km）和最小时间尺度（10 s），冕洞和宁静太阳区的辐射强度分别为22和19 km 2 s-1，而对于谱斑区，最小时间尺度为15 s时，辐射强度约为12 km 2 s-1。我们用我们的BP跟踪程序对三维MHD模型的太阳对流数据进行了处理，发现了γ = 1.45的超扩散现象。得到了湍流扩散系数与尺度和γ的关系式。
On the basis of observations of solar granulation obtained with the New Solar Telescope of Big Bear Solar Observatory, we explored proper motion of bright points (BPs) in a quiet-sun area, a coronal hole, and an active region plage. We automatically detected and traced BPs and derived their mean-squared displacements as a function of time (starting from the appearance of each BP) for all available time intervals. In all three magnetic environments, we found the presence of a super-diffusion regime, which is the most pronounced inside the time interval of 10–300 s. Super-diffusion, measured via the spectral index, γ, which is the slope of the mean-squared displacement spectrum, increases from the plage area (γ= 1.48) to the quiet-sun area (γ= 1.53) to the coronal hole (γ= 1.67). We also found that the coefficient of turbulent diffusion changes in direct proportion to both temporal and spatial scales. For the minimum spatial scale (22 km) and minimum time scale (10 s), it is 22 and 19 km 2 s− 1 for the coronal hole and the quiet-sun area, respectively, whereas for the plage area it is about 12 km 2 s− 1 for the minimum time scale of 15 s. We applied our BP tracking code to three-dimensional MHD model data of solar convection and found the super-diffusion with γ= 1.45. An expression for the turbulent diffusion coefficient as a function of scales and γ is obtained.