论文标题
关于太阳风和磁流失动力湍流的Elsasser增量的统计
On the Statistics of Elsasser Increments in Solar Wind and Magnetohydrodynamic Turbulence
论文作者
论文摘要
我们使用大量的风数据（1995年至2017年之间收集）附近1 AU研究了ELSASSER增量的经验概率分布函数（PDF）的依赖性。将经验PDF与从$ 2048^3 $矩形网格上稳定驱动的同质降低MHD湍流的高分辨率数值模拟获得的经验PDF进行了比较。通过使用基于太阳风平均特性的有条件分析，获得了大量的Alfvénic增量统计样本。发现从观测值和数值模拟获得的PDF尾巴在惯性范围内具有指数性的行为，指数减小可以满足形式的$α_l\ propto l^{ - μ} $的幂律，其中$ l $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $左右，用于仿真和0.4的模拟和0.4。假设其指数行为扩展到任意较大的增量，以确定结构函数缩放定律在非常高的阶段。我们的结果表明，有关ELSASSER增量PDF的潜在普遍缩放定律以及研究太阳风观测中高阶统计的替代方法。
We investigate the dependency with scale of the empirical probability distribution functions (PDF) of Elsasser increments using large sets of WIND data (collected between 1995 and 2017) near 1 au. The empirical PDF are compared to the ones obtained from high-resolution numerical simulations of steadily driven, homogeneous Reduced MHD turbulence on a $2048^3$ rectangular mesh. A large statistical sample of Alfvénic increments is obtained by using conditional analysis based on the solar wind average properties. The PDF tails obtained from observations and numerical simulations are found to have exponential behavior in the inertial range, with an exponential decrement that satisfies power-laws of the form $α_l\propto l^{-μ}$, where $l$ the scale size, with $μ$ around 0.2 for observations and 0.4 for simulations. PDF tails were extrapolated assuming their exponential behavior extends to arbitrarily large increments in order to determine structure function scaling laws at very high orders. Our results points to potentially universal scaling laws governing the PDF of Elsasser increments and to an alternative methodology to investigate high-order statistics in solar wind observations.
