磁流体动力学太阳风湍流中可压缩能量级联的阿尔芬性效应：来自帕克太阳探测器、太阳轨道器和WIND观测的证据
Effects of Alfvénicity on the Compressible Energy Cascade in Magnetohydrodynamic Solar Wind Turbulence: Evidence from Parker Solar Probe, Solar Orbiter, and WIND observations
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales（布宜诺斯艾利斯大学，理学院）
- CONICET – Universidad de Buenos Aires, Instituto de Física Interdisciplinaria y Aplicada (INFINA)（阿根廷国家科学研究委员会–布宜诺斯艾利斯大学，交叉与应用物理研究所）
- Department of Physics, The University of Texas at Austin（德克萨斯大学奥斯汀分校，物理系）
- Department of Astronomy, University of Maryland, College Park（马里兰大学帕克分校，天文学系）
- Planetary Magnetospheres Laboratory, NASA Goddard Space Flight Center（NASA戈达德太空飞行中心，行星磁层实验室）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用多航天器观测数据，发现阿尔芬性和风速调控太阳风湍流中可压缩与不可压缩能量级联的比值，并揭示速度涨落是级联速率的主要预测因子。
AI中文摘要：
太阳风中可压缩磁流体动力学能量级联受阿尔芬性、等离子体涨落和质子温度的影响，然而这些因素如何调节可压缩与不可压缩能量传递在日心距离上的相对权重仍知之甚少。我们将可压缩和不可压缩精确关系应用于来自WIND（1天文单位）、帕克太阳探测器（<0.25天文单位）和太阳轨道器（0.3–1天文单位）的大量2小时区间样本，将区间按阿尔芬性（|σ_c|>0.75为阿尔芬性，|σ_c|<0.25为非阿尔芬性）和风速分类，并检查可压缩级联的类亚格洛姆项和纯可压缩项。速度涨落幅度是可压缩级联速率⟨|ε_c|⟩的最强预测因子，其次是密度和磁场涨落。在所有状态下，⟨|ε_c|⟩与⟨|ε_i|⟩紧密相关，其比值由阿尔芬性和风速组织：非阿尔芬性和阿尔芬性快风聚集在⟨|ε_c|⟩=⟨|ε_i|⟩附近，而阿尔芬性慢风表现出与内能贡献一致的系统性超出。最大的⟨|ε_c|⟩系统地出现在更热的区间中，在阿尔芬性慢风和非阿尔芬性风中，从冷事件到热事件增加两个数量级，这一趋势主要由纯可压缩项主导，而占主导的类亚格洛姆项控制整体级联幅度。因此，阿尔芬性和风速控制着跨日心距离的湍流能量传递效率，可压缩与不可压缩速率之间的紧密耦合表明，需要对太阳风耗散预算进行可压缩、多流体描述。
英文摘要：
The compressible MHD energy cascade in the solar wind is shaped by Alfvénicity, plasma fluctuations, and proton temperature, yet how these factors regulate the relative weight of compressible and incompressible energy transfer across heliocentric distances remains poorly understood. We apply compressible and incompressible exact relations to a large sample of 2-hour intervals from WIND (1~au), Parker Solar Probe ($<0.25$~au), and Solar Orbiter (0.3--1~au), classifying intervals as Alfvénic ($|σ_c|>0.75$) or non-Alfvénic ($|σ_c|<0.25$) and by wind speed, and examine the Yaglom-like and purely compressible components of the compressible cascade. Velocity fluctuation amplitude is the strongest predictor of the compressible cascade rate $\langle|\varepsilon_c|\rangle$, followed by density and magnetic field fluctuations. $\langle|\varepsilon_c|\rangle$ and $\langle|\varepsilon_i|\rangle$ are tightly correlated in all regimes, with their ratio organized by Alfvénicity and wind speed: non-Alfvénic and Alfvénic fast winds cluster along $\langle|\varepsilon_c|\rangle=\langle|\varepsilon_i|\rangle$, while Alfvénic slow wind shows a systematic excess consistent with internal energy contributions. The largest $\langle|\varepsilon_c|\rangle$ systematically occur in hotter intervals, with a two-decade increase from cool to hot events in Alfvénic slow and non-Alfvénic wind, a trend carried mainly by the purely compressible term, while the dominant Yaglom-like term controls the overall cascade magnitude. Alfvénicity and wind speed thus govern the efficiency of turbulent energy transfer across heliocentric distances, and the tight coupling between compressible and incompressible rates points to the need for compressible, multi-fluid descriptions of the solar wind dissipation budget.
