ICME-HSS相互作用区Alfven波的观测
Observation of Alfven wave in ICME-HSS interaction region
摘要：
阿尔文波（Alfvén wave，AW）是太阳发射的太阳风中最常见的波动。此外，行星际日冕物质抛射（ICME）和高速流（HSS）之间的相互作用也被多次观测到。然而，这种相互作用会产生AW吗？在这种情况下，AW的性质是什么仍然是一个悬而未决的问题。为了回答这个问题，我们研究了1999年10月21日在1AU处由Wind航天器观测到的ICME-HSS相互作用事件。我们已经使用了Walén测试来识别AW和估计Elsasser变量，以找到AW的特性。我们明确地发现，ICME占主导地位的向阳AW，而尾随HSS有很强的反向阳AW。我们认为ICME-HSS相互作用使ICME的MC变形，导致MC内的AWs。此外，ICME早期重联的存在也可能是其内部AW起源的主要原因。
英文摘要：
The Alfvén wave (AW) is the most common fluctuation present within the emitted solar wind from the Sun. Moreover, the interaction between interplanetary coronal mass ejection (ICME) and high-speed stream (HSS) has been observed on several occasions. However, can such interaction generate an AW? What will be the nature of AW in such a scenario remains an open question. To answer it, we have investigated an ICME-HSS interaction event observed on 21st October 1999 at 1 AU by Wind spacecraft. We have used the Walén test to identify AW and estimated Elsasser variables to find the characteristics of the AWs. We explicitly find that ICME were dominant with Sunward AWs, whereas the trailing HSS has strong anti-Sunward AW. We suggest that the ICME-HSS interaction deforms the MC of the ICME, resulting in the AWs inside the MC. In addition, the existence of reconnection within the ICME early stage can also be the leading cause of the origin of AW within it.
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