Collaborative Research: GEM: Solar Wind Entry Sites, Paths, and Transport Mechanisms Deduced from Model-Data Comparison

该项目将详细调查太阳风等离子体进入地球等离子体片的情况。调查将采用数据分析和模型模拟相结合的方法进行，用于跟踪整个磁层的太阳风等离子体。将选择行星际磁场稳定数小时且等离子体片中卫星覆盖良好的时期作为研究的核心。将对磁层中不同位置的等离子体特性，包括磁场和拓扑结构、流量、密度和温度进行彻底的模型数据比较。将被检查的具体位置包括等离子体片，低纬度边界层（LLBL），昼侧磁层，和尖点区域。模型数据比较的目的是揭示太阳风等离子体的路径，以及随后的太阳风等离子体进入地点和机制。将特别注意热稀薄和冷稠密等离子体片之间的过渡。该研究将确定这种转变是否以连续的方式发生，或者是否存在临界IMF取向，在该取向处，进入位点发生不连续的变化。当确定等离子体片形成机制时，检查等离子体参数在磁层中不同位置随时间的变化将特别有帮助。虽然电离层肯定有助于等离子体片的形成，但该项目将侧重于太阳风的作用。然而，由于将从卫星数据中获得成分测量结果，在许多情况下，将有可能区分这些等离子体源并评估其相对重要性。这项研究将直接影响空间气象研究，因为等离子体片是内磁层等离子体的主要来源，而内磁层又是空间气象影响人类活动的主要区域之一。两名研究生将执行工作的重要组成部分，并将获得宝贵的实践培训。在这项研究的过程中，事件的数据库，其特征在于在IMF的时钟角和/或SW密度的急剧转变，同时冷稠密等离子体片和热稀薄等离子体片（CDPS/HTPS）的转变的尾巴将被编译。这一数据库将向公众开放。

This project will investigate in detail the entry of solar wind plasma into Earth's plasma sheet. The investigation will be conducted using a combination of data analysis and model simulations which will be used to track the solar wind plasma throughout the magnetosphere. Periods where the interplanetary magnetic field (IMF) is stable for several hours and there is good satellite coverage in the plasma sheet will be selected to form the core of the study. Thorough model-data comparisons of plasma properties, including magnetic field and topology, flow, density, and temperature, at different locations in the magnetosphere will be performed. The specific locations that will be examined include the plasma sheet, low-latitude boundary layer (LLBL), dayside magnetosphere, and cusp region. The purpose of the model-data comparisons is to reveal the path of the solar wind plasma and subsequently the solar wind plasma entry sites and mechanisms. Special attention will be given to the transitions between the hot tenuous and the cold dense plasma sheet. The research will determine whether such transitions occur in a continuous fashion or whether there are critical IMF orientations at which a discontinuous change in the entry sites occurs. Examining how the plasma parameters change at different locations versus time in the magnetosphere will be particularly helpful when identifying the plasma sheet formation mechanisms. Although the ionosphere certainly contributes to the formation of the plasma sheet, this project will focus on the role of the solar wind. However, because composition measurements will be available from the satellite data, in many cases it will be possible to distinguish between these plasma sources and assess their relative importance. This research will directly impact space weather studies because the plasma sheet is the primary source of plasma for the inner magnetosphere, which in turn is one of the main regions where space weather affects human activity. Two graduate students will perform significant parts of the work and will receive valuable hands-on training. In the course of this study a data base of events that are characterized by sharp transitions in the IMF clock angle and/or the SW density concurrent with cold dense plasma sheet and hot tenuous plasma sheet (CDPS/HTPS) transitions in the tail will be compiled. This data base will be made publicly available.