地球磁鞘:结构、波动与湍流

The Earth's magnetosheath:Structures,waves and turbulence

地球磁鞘是位于弓激波和磁层顶之间的过渡区域.磁鞘作为太阳风和地球磁层直接作用的区域,其间发生的物理过程对磁层有着直接的影响,因此磁鞘的研究对于理解磁层动力学过程以及空间天气等具有重要的意义.地球磁鞘是研究等离子体动力学的天然实验室,在磁鞘中存在着多种多样的结构和波动现象;同时,磁鞘等离子体的湍动特性也为研究等离子体湍流提供了良好的条件.近年来,得益于Cluster和MMS等卫星的高精度等离子体和电磁场数据,磁鞘中的一些等离子体动力学过程得到了深入的研究.本文主要回顾近年来国内学者利用Cluster和MMS卫星数据在研究地球磁鞘的结构、波动和湍流方面取得的最新进展,同时也提出了一些尚未解决的问题和未来可能研究的方向.

When the solar wind encounters the blunt Earth's magnetosphere,a detached shock(i.e.,the bow shock)forms at a distance about ten Earth radii from the Earth.The Earth's magnetosheath is a spatially-bounded transition region between the bow shock and the magnetopause,which directly interfaces with the magnetosphere.As the dynamic processes occurring in the magnetosheath may directly influence the magnetosphere,research on the magnetosheath has an important impact on our understanding of the magnetospheric dynamics and space weather.The magnetosheath is a natural laboratory of plasma dynamics,exhibiting various types of structures and waves.Studying these structures and waves can help us understand the magnetosheath's dynamic processes and nonlinear wave-particle interactions.Also,the magnetosheath provides an advantage condition for studying plasma turbulence.Turbulence within the magnetosheath features a distinctive characteristic than the solar wind turbulence,which provides another important in-situ turbulence laboratory except for the solar wind.Thanks to the high-resolution plasma measurements from the Cluster and Magnetospheric Multiscale(MMS)mission,some dynamic phenomena can be studied by in-situ observations in the magnetosheath.This paper reviews recent advances in studying the structure,waves and turbulence of the Earth's magnetosheath.Moreover,we primarily focus on domestic research using the Cluster and MMS missions data.The review is organized a brief introduction to the magnetosheath is provided.Then,the related researches on structures,waves and turbulence are described in three sec-tions,respectively.At last,we also discuss some unsolved problems and the possible future research directions.