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

该项目将详细研究太阳风等离子体进入地球等离子体层的过程。这项调查将结合数据分析和模型模拟来跟踪整个磁层的太阳风等离子体。将选择行星际磁场（IMF）稳定数小时且等离子体层内有良好卫星覆盖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进行全面的模型数据比较，包括磁场和拓扑结构、流量、密度和温度。将被检查的具体位置包括等离子体层、低纬度边界层（LLBL）、日侧磁层和尖峰区。模型数据比较的目的是揭示太阳风等离子体的路径，进而揭示太阳风等离子体进入的位置和机制。将特别注意热的稀薄和冷的致密等离子体片之间的转变。研究将确定这种转变是否以连续的方式发生，或者是否存在关键的IMF方向，在该方向上，进入地点发生了不连续的变化。研究等离子体参数在磁层中不同位置随时间的变化将特别有助于确定等离子体片的形成机制。虽然电离层肯定有助于等离子体层的形成，但该项目将重点放在太阳风的作用上。然而，由于可以从卫星数据中获得成分测量，在许多情况下，将有可能区分这些等离子体源并评估它们的相对重要性。这项研究将直接影响空间天气研究，因为等离子层是内磁层等离子体的主要来源，而内磁层又是空间天气影响人类活动的主要区域之一。两名研究生将完成工作的重要部分，并将接受宝贵的实践培训。在本研究过程中，将编制以IMF时钟角急剧转变和/或SW密度与尾部冷致密等离子体片和热稀薄等离子体片（CDPS/HTPS）转变同时发生为特征的事件数据库。这个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.