DIRECT AND INVERSE CASCADES IN THE ACCELERATION REGION OF THE FAST SOLAR WIND
DIRECT AND INVERSE CASCADES IN THE ACCELERATION REGION OF THE FAST SOLAR WIND
复制标题
快太阳风加速区的正向和反向级联
DOI：
10.3847/1538-4357/835/1/10
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M. Asgari
中科院分区：
文献类型：
--
作者：
A. A. Ballegooijen;M. Asgari
阿尔芬波被认为在日冕洞发出的快速太阳风的加热和加速中起着重要作用。主波和次波之间的非线性相互作用有可能将波能转移到较小的垂直尺度(“正级联”)或较大的尺度(“逆级联”)。在本文中，我们使用简化的磁流体动力学(RMHD)模拟来研究级联速率如何依赖于垂直波数和离太阳中心的径向距离。对于背景大气平坦的模式，我们发现，在惯性范围()内，半径为1.4和无量纲波数之间的主波出现了逆级联()，而在其他地方则出现了直接级联()。对于具有密度涨落的模型，存在具有逆级联的多个区域。在这两种情况下，级联速率随垂直波数的变化而显著不同，表明级联是一个高度非局域的过程。由于逆级联，能量耗散率远低于唯象模型的预期，不足以维持背景大气的温度。我们得出的结论是，RMHD模型不能再现快速太阳风的观测特性。
Alfvén waves are believed to play an important role in the heating and acceleration of the fast solar wind emanating from coronal holes. Nonlinear interactions between the dominant waves and minority waves have the potential to transfer wave energy either to smaller perpendicular scales (“direct cascade”) or to larger scales (“inverse cascade”). In this paper we use reduced magnetohydrodynamic (RMHD) simulations to investigate how the cascade rates depend on perpendicular wavenumber and radial distance from the Sun center. For models with a smooth background atmosphere, we find that an inverse cascade ( ) occurs for the dominant waves at radii between 1.4 and and dimensionless wavenumbers in the inertial range ( ), and a direct cascade ( ) occurs elsewhere. For a model with density fluctuations, there are multiple regions with an inverse cascade. In both cases, the cascade rate varies significantly with perpendicular wavenumber, indicating that the cacsade is a highly nonlocal process. As a result of the inverse cascades, the energy dissipation rates are much lower than expected from a phenomenological model and are insufficient to maintain the temperature of the background atmosphere. We conclude that RMHD models are unable to reproduce the observed properties of the fast solar wind.
影响因子：
6.5
作者：
D. Banerjee;D. Pérez-Suárez;J. G. Doyle
通讯作者：
D. Banerjee;D. Pérez-Suárez;J. G. Doyle