Blanco-Cano X, Rojas-Castillo D, Kajdič P, Preisser L
Instituto de Geofísica Universidad Nacional Autónoma de México Circuito de la Investigación Científica s/n Ciudad Universitaria Mexico City Mexico.
Space Research Institute Austrian Academy of Sciences Graz Austria.
J Geophys Res Space Phys. 2023 Jul;128(7):e2022JA031221. doi: 10.1029/2022JA031221. Epub 2023 Jul 22.
Magnetosheath jets are localized plasma structures with high dynamic pressure which are frequently observed downstream of the Earth's bow shock. In this work we analyze Magnetospheric MultiScale magnetic field and plasma data and show that jets can be found in the quasi-perpendicular magnetosheath in regions permeated by Mirror mode waves (MMWs). We show that structures identified as jets by their enhanced dynamic pressure can have very different internal structure, with variable signatures in magnetic field magnitude and components, velocity, and density and can be associated to ion distribution functions of various types. This suggests that jets observed in the quasi-perpendicular magnetosheath are generated by different mechanisms. We find that jets can be related to traveling foreshocks, flux transfer events, and some have MMWs inside them. Our results suggest that some jets have a local source and their formation does not depend on upstream structures. We find that different types of ion distributions can exist inside the jets, while in some cases anisotropic distributions are present, in others counterstreaming distributions exist. We also show that for jets with MMWs inside them, ion distributions can be modulated. This highlights the importance of using ion distributions to identify and classify different types of jets.
磁鞘喷流是具有高动压的局部等离子体结构，经常在地球弓形激波下游观测到。在这项工作中，我们分析了磁层多尺度磁场和等离子体数据，结果表明，在准垂直磁鞘中由镜像模波（MMWs）渗透的区域可以发现喷流。我们表明，通过其增强的动压识别为喷流的结构可能具有非常不同的内部结构，在磁场大小和分量、速度和密度方面具有可变特征，并且可以与各种类型的离子分布函数相关联。这表明在准垂直磁鞘中观测到的喷流是由不同机制产生的。我们发现喷流可能与行进的前震、通量传输事件有关，并且有些喷流内部存在MMWs。我们的结果表明，一些喷流有局部源，其形成不依赖于上游结构。我们发现喷流内部可以存在不同类型的离子分布，在某些情况下存在各向异性分布，在其他情况下存在反向流动分布。我们还表明，对于内部有MMWs的喷流，离子分布可以被调制。这突出了利用离子分布来识别和分类不同类型喷流的重要性。
