Turbulent Transport in a Three-dimensional Solar Wind
Turbulent Transport in a Three-dimensional Solar Wind
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DOI：
10.3847/1538-4357/aa60bc
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发表时间：
2017-03
期刊：
影响因子：
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通讯作者：
D. Shiota;G. Zank;L. Adhikari;P. Hunana;D. Telloni;R. Bruno
中科院分区：
文献类型：
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作者：
D. Shiota;G. Zank;L. Adhikari;P. Hunana;D. Telloni;R. Bruno
太阳风中的湍流对日冕和太阳风等离子体的加热以及太阳风和高能粒子的加速起着至关重要的作用。湍流源还没有被很好地理解，并且被认为部分地通过与太阳风和行星际磁场的大尺度不均匀性的相互作用和/或从太阳日冕传输而增强。为了研究与背景不均匀性和湍流源的相互作用，我们利用Zank等人的理论模型建立了一个新的三维MHD模型，其中包括湍流的输运和耗散。我们求解了三个矩或变量的时空演化、前向和后向波动模态的能量和剩余能量以及它们对应的三个相关长度。传输模型与非均匀太阳风的三维模型相结合。我们提出了耦合太阳风-湍流模型的结果，假设一个简单的倾斜偶极子磁配置，模拟太阳最小条件，以及几个比较的中间情况。通过考虑8种可能的太阳风和湍流源配置，我们发现大尺度太阳风和IMF的不均匀性以及湍流源的强度显著影响6 au内日球层湍流的分布。我们将一个完整的太阳极小期模型预测的湍流分布结果与太阳神号和尤利西斯号航天器的现场测量结果进行了比较，发现湍流强度的合成剖面与观测结果基本一致。
Turbulence in the solar wind can play essential roles in the heating of coronal and solar wind plasma and the acceleration of the solar wind and energetic particles. Turbulence sources are not well understood and thought to be partly enhanced by interaction with the large-scale inhomogeneity of the solar wind and the interplanetary magnetic field and/or transported from the solar corona. To investigate the interaction with background inhomogeneity and the turbulence sources, we have developed a new 3D MHD model that includes the transport and dissipation of turbulence using the theoretical model of Zank et al. We solve for the temporal and spatial evolution of three moments or variables, the energy in the forward and backward fluctuating modes and the residual energy and their three corresponding correlation lengths. The transport model is coupled to our 3D model of the inhomogeneous solar wind. We present results of the coupled solar wind-turbulence model assuming a simple tilted dipole magnetic configuration that mimics solar minimum conditions, together with several comparative intermediate cases. By considering eight possible solar wind and turbulence source configurations, we show that the large-scale solar wind and IMF inhomogeneity and the strength of the turbulence sources significantly affect the distribution of turbulence in the heliosphere within 6 au. We compare the predicted turbulence distribution results from a complete solar minimum model with in situ measurements made by the Helios and Ulysses spacecraft, finding that the synthetic profiles of the turbulence intensities show reasonable agreement with observations.