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arXiv 2003.01823astro-ph.SR
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太阳耀斑预报的一种新方法

A New Approach to Solar Flare Prediction

Michael L. Goodman, Chiman Kwan, Bulent Ayhan, Eric L. Shang

备注：
37 pages, 15 figures. Corresponding author - Michael L. Goodman
发表信息：
Frontiers of Physics 15(3), 34601 (2020)
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摘要：

由于自由磁能量耗散，需要电流密度的所有三个分量来计算加热速率。在这里，我们提出了一个新的模型，以确定是否在活动区（AR）光球的电阻加热率的增加的时间与随后发生的M和X耀斑的日冕的第一次测试。一个数据驱动的，3D，非力自由磁流体动力学模型限制到近光球区域被用来计算的时间序列的完整的电流密度和电阻加热率每单位体积$(Q(t))$在每个像素的中性线区域（NLR）的14 AR。该模型是由太阳动力学观测卫星（SDO）上的日震和磁成像仪测量的磁场${\bf B}$的时间序列驱动的。在每个AR像素中，从${\bf B}$的时间序列中滤除由于SDO轨道运动引起的伪多普勒周期。对于每个AR，累积分布函数（CDF）的值的NLR面积积分$Q_i(t)$的$Q(t)$被发现是一个标度不变的幂律分布基本上相同的观测CDF的总能量释放在日冕耀斑。这表明日冕耀斑和光球$Q_i$是相关的，并由相同的过程驱动。该模型预测$Q_i$峰值的值高于背景值几个数量级。这些尖峰由电流密度的非无力分量中的尖峰驱动。这些尖峰的时间与几小时到几天后的M或X耀斑的时间有着明显的相关性。尖峰出现在颗粒化尺度上，可能是水平电流片加热的特征。研究还发现，NLR无符号磁通量变化率相对较大的时间也与随后的M和X耀斑以及$Q_i$尖峰的时间相关。

英文摘要：

All three components of the current density are required to compute the heating rate due to free magnetic energy dissipation. Here we present a first test of a new model developed to determine if the times of increases in the resistive heating rate in active region (AR) photospheres are correlated with the subsequent occurrence of M and X flares in the corona. A data driven, 3 D, non-force-free magnetohydrodynamic model restricted to the near-photospheric region is used to compute time series of the complete current density and the resistive heating rate per unit volume $(Q(t))$ in each pixel in neutral line regions (NLRs) of 14 ARs. The model is driven by time series of the magnetic field ${\bf B}$ measured by the Helioseismic & Magnetic Imager on the Solar Dynamics Observatory (SDO) satellite. Spurious Doppler periods due to SDO orbital motion are filtered out of the time series for ${\bf B}$ in every AR pixel. For each AR, the cumulative distribution function (CDF) of the values of the NLR area integral $Q_i(t)$ of $Q(t)$ is found to be a scale invariant power law distribution essentially identical to the observed CDF for the total energy released in coronal flares. This suggests that coronal flares and the photospheric $Q_i$ are correlated, and powered by the same process. The model predicts spikes in $Q_i$ with values orders of magnitude above background values. These spikes are driven by spikes in the non-force free component of the current density. The times of these spikes are plausibly correlated with times of subsequent M or X flares a few hours to a few days later. The spikes occur on granulation scales, and may be signatures of heating in horizontal current sheets. It is also found that the times of relatively large values of the rate of change of the NLR unsigned magnetic flux are also plausibly correlated with the times of subsequent M and X flares, and spikes in $Q_i$.

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