Magnetospheric Current Sheets and Boundary Layers

磁层电流片和边界层

• 批准号: 9422918
• 负责人: Bengt Sonnerup
• 金额: $ 34.31万
• 依托单位: Dartmouth College
• 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 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9422918&HistoricalAwards=false
• 关键词: Magnetospheric; Current; Sheets; Boundary; Layers

The proposed work represents continuation of an ongoing research program concerned with some of the physical processes and structures that occur in thin electrical current sheets and plasma boundary layers in the Earth's magnetosphere, with special emphasis on the magnetopause. This current sheet forms the outer boundary of the magnetosphere and separates it from the rapidly streaming solar wind. The proposed research is concerned with five related problem areas: o Construction, from spacecraft data, of magnetic field "transects" describing the draping of magnetic field inside or outside the magnetopause over elongated bulges moving in a transverse sense along that layer. The result will be a robust and thoroughly bench-marked data analysis tool that can be used by other researchers. Applications include, not just traveling bulges and waves on the magnetopause, but other moving current filaments, e.g., in the low latitude boundary layer or in the geomagnetic tail. o Construction of similar transects describing mesoscale magnetic structures, such as tearing mode islands, in the magnetopause itself. Again, the goal is to develop and test a robust data analysis tool that is expected to be of utility and importance for study of two-dimensional structures in the magnetopause. o Theoretical study of weakly nonlinear wave pulses propagating on the magnetopause and their relation to observed bulges moving along that year. o Theoretical study of strong nonlinearities in steady, two- dimensional, field-aligned MHD flows, including transitions between elliptic and hyperbolic states. Search for, and analysis of, illustrative events in spacecraft data. o Theoretical study of MHD flow in two-dimensional reconnection layers. In each area, the research will start with analytical and associated numerical work, including, where appropriate, the generation of synthetic spacecraft data for bench marking of the data analysis techniques; this phase will be followed by identificaion of sample events and by testing of the new techniques on spacecraft data, initially from AMPTE/IRM, but later in the project, from the CLUSTER mission.

这项提议的工作代表了一项正在进行的研究计划的继续，该研究计划涉及地球磁层中薄电流片和等离子体边界层中发生的一些物理过程和结构，特别强调磁层顶。这个电流片形成了磁层的外边界，并将其与快速流动的太阳风分开。提出的研究涉及五个相关的问题领域：o根据航天器数据构建磁场“横断面”，描述磁场在磁层顶内外沿该层横向移动的细长凸起上的悬垂。结果将是一个强大的和彻底的基准数据分析工具，可以被其他研究人员使用。应用范围不仅包括磁层顶的移动凸起和波，还包括其他移动电流细丝，例如，在低纬度边界层或地磁尾。o在磁层顶本身构建描述中尺度磁性结构的类似横断面，例如撕裂模式岛。同样，目标是开发和测试一种强大的数据分析工具，该工具有望在磁层顶的二维结构研究中发挥重要作用。o在磁层顶传播的弱非线性波脉冲的理论研究及其与观测到的当年移动的凸起的关系。对稳定的、二维的、场向的MHD流的强非线性的理论研究，包括椭圆态和双曲态之间的转换。搜索和分析宇宙飞船数据中的说明事件。o二维重连层中MHD流动的理论研究。在每一个领域，研究将从分析和有关的数值工作开始，包括酌情生成综合航天器数据，以便对数据分析技术进行基准测试；在此阶段之后，将确定样本事件，并对航天器数据的新技术进行测试，这些数据最初来自AMPTE/IRM，但在该项目后期，将来自CLUSTER任务。