论文标题
马尔可夫湍流在动力学尺度上的磁层多尺度观察
Magnetospheric Multiscale Observations of Markov Turbulence on Kinetic Scales
论文作者
论文摘要
在我们先前的研究中，我们检查了太阳风和磁层等离子体的湍流，包括大型惯性磁性流动力尺度上的马尔可夫特征。在这里，我们介绍了基于磁层多尺度任务在较小的动力学尺度下，磁场波动的统计分析结果。在我们在光谱分析上的结果下，非常大的斜率约为-16/3，我们在这种动力学方面应用马尔可夫过程方法来湍流。结果表明，满足了Chapman-Kolmogorov方程，并且描述幂律依赖性漂移和扩散的最低阶kramers-Moyal系数与广义的Ornstein-uhlenbeck过程一致。 Fokker-Planck方程的解决方案与实验概率密度函数一致，该功能通过动力学域表现出通用的全球尺度不变性。特别是，对于中等尺度，我们的kappa分布由各种具有重尾的峰形形状描述，其较大的kappa参数值将减少到高斯分布中，以用于大惯性尺度。这表明湍流级联反应也可以通过很小的尺度上描述。在动力学尺度上获得的结果可能有助于更好地理解有关湍流的物理机制
In our previous studies we have examined solar wind and magnetospheric plasmas turbulence, including Markovian character on large inertial magneto-hydrodynamic scales. Here we present the results of statistical analysis of magnetic field fluctuations in the Earth's magnetosheath based on Magnetospheric Multiscale mission at much smaller kinetic scales. Following our results on spectral analysis with very large slopes of about -16/3, we apply Markov processes approach to turbulence in this kinetic regime. It is shown that the Chapman-Kolmogorov equation is satisfied and the lowest-order Kramers-Moyal coefficients describing drift and diffusion with a power-law dependence are consistent with a generalized Ornstein-Uhlenbeck process. The solutions of the Fokker-Planck equation agree with experimental probability density functions, which exhibit a universal global scale invariance through the kinetic domain. In particular, for moderate scales we have the kappa distribution described by various peaked shapes with heavy tails, which with large values of kappa parameter are reduced to the Gaussian distribution for large inertial scales. This shows that the turbulence cascade can be described by the Markov processes also on very small scales. The obtained results on kinetic scales may be useful for better understanding of the physical mechanisms governing turbulence
