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.

对地球等离子体片低速流动状态的性质进行了统计分析。 低流动状态等离子体片（即，安静时间等离子体片）被定义为PI先前研究的突发整体流事件（BBF事件）状态的补充。 低流量状态是等离子体片中的流的最可能状态，因为其包括92- 95%的可用等离子体片数据集。 这种流动状态具有平均流动模式，可以用等离子体片的2流体图像来解释。 将利用目前的磁场模型绘制这种流动模式在电离层上的分布图，并将审查这种模式对货币基金组织部门的依赖性。 非BBF流具有比等离子体片中的平均流速大许多倍的方差，并且即使在低AE条件下也持续存在。 流动的不稳定性可能允许等离子体片中的对流进行，与压力平衡不一致的论点相反。 因此，在不同的地磁条件下，在X-Y平面上的不同位置的流动变化，以及向地对流和流动变化之间的相关性将被研究。 流量的可变性将被纳入等离子体片平衡的定性模型。 安静等离子体片流场的理论指导下的统计分析渴望表征的等离子体片的基态的基本属性及其相关的全球磁层环流。