超米粒组织作为太阳活动周期变化的示踪剂
Supergranulation as a Tracer of Solar-Cycle Variability
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中文总结 AI 辅助
研究利用自动化框架，通过时间距离日震学推断的地下水平速度图识别和表征超米粒结构，分析16年SDO/HMI观测数据，揭示超米粒特性与太阳活动周期的关系，确立其为近表面对流变化的敏感示踪剂。
中文摘要 AI 辅助
超米粒组织是近表面太阳对流的主要尺度之一，为研究对流、自转和磁活动之间的相互作用提供了重要诊断。我们开发了一个自动化框架，利用从时间距离日震学推断出的地下水平速度图来识别和表征超米粒结构。该方法将高斯-拉普拉斯检测应用于水平速度散度图，并结合磁场掩蔽、基于散度的滤波和多峰抑制，以在宁静太阳和活动条件下分离超米粒单元。我们用此方法分析了16年的太阳动力学观测站/日震磁成像仪（SDO/HMI）观测数据，研究超米粒特性的时间和纬度变化。结果揭示了明显的太阳活动周期依赖性：平均超米粒直径在太阳极大值附近减小，在太阳极小值附近增大，且在较弱的第24太阳活动周中的超米粒比在较强的第25太阳活动周中更大。直径分布宽度在高磁活动期间增加，而检测到的超米粒数量仅显示出微弱的周期依赖性。检测到的超米粒内的平均速度散度与黑子数强烈反相关，表明磁对发散对流的抑制。超米粒直径和散度的时间-纬度分布紧密跟随太阳活动带的迁移，而水平速度的旋度显示出微弱的周期依赖性但明显的半球不对称性。这些结果确立了超米粒组织作为近表面对流中与太阳活动周期相关变化的敏感示踪剂。
英文摘要
Supergranulation is one of the dominant scales of near-surface solar convection and provides an important diagnostic for studying the interaction between convective flows, rotation, and magnetic activity. We develop an automated framework to identify and characterize supergranular structures using subsurface horizontal-velocity maps inferred from time-distance helioseismology. The method applies Laplacian-of-Gaussian detection to horizontal velocity divergence maps and combines this with magnetic-field masking, divergence-based filtering, and multi-peak rejection to isolate supergranular cells under both quiet-Sun and active conditions. Using this approach, we analyze 16 years of SDO/HMI observations spanning Solar Cycles 24 and 25 and investigate temporal and latitudinal variations of supergranular properties. The results reveal a clear solar-cycle dependence: the mean supergranular diameter decreases near solar maxima and increases around solar minima, with systematically larger supergranules in the weaker Solar Cycle 24 than in the stronger Solar Cycle 25. The width of the diameter distribution increases during high magnetic activity, whereas the number of detected supergranules shows only weak cycle dependence. The mean velocity divergence within detected supergranules is strongly anticorrelated with sunspot number, indicating magnetic suppression of divergent convective flows. Time-latitude distributions of supergranular diameter and divergence closely follow the migration of solar activity belts, while the curl of the horizontal velocity shows weak cycle dependence but pronounced hemispheric asymmetry. These results establish supergranulation as a sensitive tracer of solar-cycle-related changes in near-surface convection.
