Local Helioseismology and Correlation Tracking Analysis of Surface Structures in Realistic Simulations of Solar Convection
Local Helioseismology and Correlation Tracking Analysis of Surface Structures in Realistic Simulations of Solar Convection
复制标题
太阳对流真实模拟中的局地日震学和表面结构相关跟踪分析
DOI：
10.1086/511148
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
Å. Nordlund
中科院分区：
文献类型：
--
作者：
D. Georgobiani;Junwei Zhao;A. Kosovichev;D. Benson;R. Stein;Å. Nordlund
我们将时距日震学、局部相关跟踪和傅里叶时空滤波方法应用于太阳对流的真实超颗粒尺度模拟，并将结果与太阳和日光层观测站 (SOHO) 迈克尔逊多普勒成像仪 (MDI) 的高分辨率观测结果进行比较。我们的目标是研究地表和地下对流结构并测试日震测量。计算域的大小和网格足以解析从粒化到超粒化的各种对流尺度。对于大于颗粒的尺度，空间速度谱近似为幂律，随着尺寸的增加，速度幅度连续减小。除了颗粒化之外，不存在特殊的尺度，尽管可以看到超颗粒化尺度下功率的小幅增强。我们计算了 f 模式和 p 模式的时间距离图，并表明它与 SOHO MDI 观测结果一致。根据模拟数据，我们计算表面重力波（f 模式）的传播时间图。我们还将相关跟踪应用于光球中的模拟垂直速度，以计算相应的水平流。我们将这两者与实际的大规模（过滤后）模拟速度进行比较。所有三种方法都揭示了类似的大规模对流模式，并为时间距离方法提供了初步测试。
We apply time-distance helioseismology, local correlation tracking, and Fourier spatial-temporal filtering methods to realistic supergranule scale simulations of solar convection and compare the results with high-resolution observations from the Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI). Our objective is to investigate the surface and subsurface convective structures and test helioseismic measurements. The size and grid of the computational domain are sufficient to resolve various convective scales from granulation to supergranulation. The spatial velocity spectrum is approximately a power law for scales larger than granules, with a continuous decrease in velocity amplitude with increasing size. Aside from granulation no special scales exist, although a small enhancement in power at supergranulation scales can be seen. We calculate the time-distance diagram for f- and p-modes and show that it is consistent with the SOHO MDI observations. From the simulation data we calculate travel-time maps for surface gravity waves (f-mode). We also apply correlation tracking to the simulated vertical velocity in the photosphere to calculate the corresponding horizontal flows. We compare both of these to the actual large-scale (filtered) simulation velocities. All three methods reveal similar large-scale convective patterns and provide an initial test of time-distance methods.