GEM: On the Quiet-Time Flow Variability in the Earth's Plasma Sheet

GEM：关于地球等离子体片中的安静时间流动变化

• 批准号: 9501545
• 负责人: Vassilis Angelopoulos
• 金额: $ 7.5万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9501545&HistoricalAwards=false
• 关键词: GEM; Quiet; Time; Flow; Variability

A statistical analysis of the properties of the low-speed flow state of the earth's plasma sheet is approved. The low flow state plasma sheet (i.e., the quiet-time plasma sheet), is defined as the complementary of the bursty bulk flow event (BBF event) state, previously studied by the PI. The low flow state is the most probable state of the flow in the plasma sheet as it comprises 92- 95% of the available plasma sheet datasets. This flow state possesses an average flow pattern that can be explained in terms of a 2-fluid picture of the plasma sheet. That flow pattern will be mapped on the ionosphere by use of current magnetic field models, and the dependence of that pattern on the IMF sector will be examined. The non-BBF flows have a variance that is many times larger than the average flow speed in the plasma sheet and persist even during low AE conditions. The unsteadiness of the flow may allow convection in the plasma sheet to proceed, contrary to the pressure balance inconsistency argument. Thus the flow variability under different geomagnetic conditions, and in different locations on the X-Y plane will be studied as well as the correlation between earthward convection and flow variability. The flow variability will be incorporated in a qualitative model of the plasma sheet equilibrium. The theory-guided statistical analysis of the quiet plasma sheet flow field aspires to characterize the basic properties of the ground state of the plasma sheet and its relevance to global magnetospheric circulation.

对地球等离子体层低速流动状态特性的统计分析已获得批准。 低流动状态血浆片（即安静时间血浆片）被定义为 PI 先前研究的突发整体流动事件（BBF 事件）状态的补充。 低流量状态是血浆片中最可能的流动状态，因为它包含 92-95% 的可用血浆片数据集。 这种流动状态具有平均流动模式，可以用血浆片的 2 流体图来解释。 将使用当前磁场模型将该流动模式映射到电离层上，并将检查该模式对 IMF 扇区的依赖性。 非 BBF 流的方差比血浆片中的平均流速大许多倍，并且即使在低 AE 条件下也持续存在。 流动的不稳定可能允许等离子体片中的对流继续进行，这与压力平衡不一致的论点相反。 因此，将研究不同地磁条件下和X-Y平面上不同位置的流量变率以及对地对流和流量变率之间的相关性。 流量变化将被纳入血浆片平衡的定性模型中。 对安静等离子体片流场进行理论引导的统计分析旨在表征等离子体片基态的基本特性及其与全球磁层环流的相关性。