Large amplitude fluctuations, often with characteristics reminiscent of large amplitude Alfvén waves propagating away from the Sun, are ubiquitous in the solar wind. Such features are most frequently found within fast solar wind streams and most often at solar minimum. The fluctuations found in slow solar wind streams usually have a smaller relative amplitude, are less Alfvénic in character and present more variability. However, intervals of slow wind displaying Alfvénic correlations have been recently identified in different solar cycle phases. In the present paper we report Alfvénic slow solar wind streams seen during the maximum of solar activity that are characterized not only by a very high correlation between velocity and magnetic field fluctuations (as required by outwardly propagating Alfvén modes) – comparable to that seen in fast wind streams – but also by higher amplitude relative fluctuations comparable to those seen in fast wind. Our results suggest that the Alfvénic slow wind has a different origin from the slow wind found near the boundary of coronal holes, where the amplitude of the Alfvénic fluctuations decreases together with decreasing the wind speed.

中文翻译：

---

阿尔文太阳风中的大振幅波动

大振幅波动，通常具有让人联想到远离太阳传播的大振幅阿尔文波的特征，在太阳风中无处不在。这种特征最常见于快速太阳风流中，最常见于太阳活动极小期。在缓慢的太阳风流中发现的波动通常具有较小的相对幅度，在特征上较少阿尔芬奇并且呈现出更多的可变性。然而，最近在不同的太阳周期阶段发现了显示阿尔芬相关性的慢风间隔。在本文中，我们报告了在太阳活动最大期间看到的阿尔文慢太阳风流，其特征不仅在于速度和磁场波动之间非常高的相关性（如向外传播的阿尔文模式所要求的）——与快速风流——但也有更高幅度的相对波动，与在快风中看到的波动相当。我们的研究结果表明，阿尔文慢风的起源与在日冕孔边界附近发现的慢风不同，阿尔文波动的幅度随着风速的降低而减小。