SuperDARN studies of magnetospheric ULF waves and boundaries

磁层 ULF 波和边界的 SuperDARN 研究

• 批准号: 227429-2010
• 负责人: Fenrich, Frances
• 金额: $ 1.97万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=454530
• 关键词: SuperDARN; studies; magnetospheric; ULF; waves

Ultra-low-frequency (ULF) waves propagating within the magnetic field and hot ionized gas (plasma) of interplanetary and near-Earth space constitute one of the most important means by which energy is exchanged within and between the outflowing stream of solar plasma, the solar wind, and the Earth's magnetic field environment, the magnetosphere. Magnetospheric ULF waves are known to be associated with important phenomena such as auroral arcs, substorms, radiation belt energization, and magnetic reconnection. Yet the source mechanism driving much of the discrete ULF wave activity in the magnetosphere remains unconfirmed and is currently a topic of considerable debate. In particular there is a class of ULF wave in the magnetosphere called the field line resonance (FLR) where the Earth's magnetic field lines resonate at their characteristic frequency like a standing wave on a string. Remarkably these FLRs are often observed at very discrete and reproducible frequencies and the reason for this is not understood. An emerging idea is that discrete oscillations in the solar wind directly drive ULF waves in the magnetosphere including the discrete FLRs. The first objective of this proposal is to determine what proportion of magnetospheric ULF waves are driven directly by a solar wind wave source. The second objective is to investigate how magnetospheric ULF waves evolve in time and space from the magnetopause boundary to the inner magnetosphere and down to the ionosphere. To achieve these objectives a database of magnetospheric ULF wave events will be compiled and analyzed using the Super Dual Auroral Radar Network (SuperDARN), an international network of high frequency radars which measures high latitude ionospheric plasma flows with high time and spatial resolution. SuperDARN convection maps will also be used to develop a new ionospheric convection gradient technique to study magnetospheric boundaries and dynamics.

在行星际和近地空间的磁场和热电离气体（等离子体）中传播的超低频（ULF）波构成了太阳等离子体流出流（太阳风）和地球磁场环境（磁层）内部和之间进行能量交换的最重要手段之一。 磁层超低频波与极光弧、亚暴、辐射带扰动和磁场重联等重要现象有关。 然而，驱动磁层中大部分离散ULF波活动的源机制仍未得到证实，目前是一个相当有争议的话题。 特别是在磁层中有一类称为场线共振（FLR）的超低频波，其中地球的磁场线以其特征频率共振，就像弦上的驻波。 值得注意的是，这些FLR经常在非常离散和可再现的频率下观察到，其原因尚不清楚。 一个新兴的想法是，太阳风中的离散振荡直接驱动磁层中的ULF波，包括离散的FLR。 这项建议的第一个目标是确定磁层超低频波的比例是由太阳风波源直接驱动的。 第二个目标是研究磁层超低频波从磁层顶边界到内磁层再到电离层的时空演化。 为了实现这些目标，将利用超级双极光雷达网（SuperDARN）汇编和分析磁层超低频波事件数据库，该雷达网是一个国际高频雷达网，以高时间和空间分辨率测量高纬度电离层等离子体流。 超级DARN对流图还将用于开发新的电离层对流梯度技术，以研究磁层边界和动态。