Collaborative Research: GEM: Global Modeling of the Magnetosheath Using Comparisons Between MHD, Hybrid Simulations and Observations

该项目将对全球三维磁流体(MHD)模拟和地球磁鞘和磁层顶混合模拟的结果进行一系列系统的比较。混合模拟将把电子视为流体，但将离子视为动能粒子。这些模拟将相互比较，并与THEMIS和集群航天器飞行任务的观测结果进行比较。这些比较研究的结果将有可能确定发生在磁鞘及其边界上的局部动力学过程在哪里、如何以及在多大程度上改变了对其大尺度性质和动力学的MHD预测。这项研究将极大地提高对局部过程对从太阳风到磁层的大规模质量、能量和动量传输的影响的理解，并将确定可以可靠地使用全球MHD模拟的太阳风等离子体体系和IMF取向。全球MHD模拟已经成为模拟太阳风与地球相互作用的标准方法--S磁层。这样的模型对于预测磁暴等空间天气影响至关重要。然而，航天器观测揭示了这种相互作用中的一些效应，这些效应不是MHD模拟所能描述的。这个项目将提高我们对MHD模拟何时以及在什么条件下可以用于空间天气预报的理解。该项目还将包括一个教育部分，让一名研究生参与研究的各个方面。

This project will perform of a series of systematic comparisons between the results of global three-dimensional magnetohydrodynamic (MHD) simulations and hybrid simulations of Earth's magnetosheath and magnetopause. The hybrid simulations will treat the electrons as a fluid but will treat the ions as kinetic particles. The simulations will be compared with each other as well as with observations from the THEMIS and Cluster spacecraft missions. Results of these comparative studies will make it possible to determine where, how, and to which extent local kinetic processes occurring in the magnetosheath and at its boundaries alter the MHD predictions of its large-scale properties and dynamics. The research will considerably improve the understanding of the effects of local processes on the large-scale transport of mass, energy, and momentum from the solar wind to the magnetosphere and will ascertain the solar wind plasma regimes and IMF orientations for which global MHD simulations can be used reliably.Global MHD simulations have been the standard approach to modeling how the solar wind interacts with Earth?s magnetosphere. Such modeling is crucial to predicting space weather effects such as magnetic storms. Spacecraft observations, however, have revealed a number of effects in that interaction that cannot be described by MHD simulations. This project will improve our understanding of when and under what conditions MHD simulations can be relied on for space weather forecasting. The project will also include an educational component by involving a graduate student who will participate in every aspect of the research.