Collaborative Research: GEM: Propagation and Dissipation of Electromagnetic Ion Cyclotron Waves in the Magnetosphere and Ionosphere

合作研究：GEM：磁层和电离层中电磁离子回旋波的传播和耗散

• 批准号: 2247396
• 负责人: Mark Engebretson
• 金额: $ 10.69万
• 依托单位: Augsburg University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247396&HistoricalAwards=false
• 关键词: Collaborative; Research; GEM; Propagation; Dissipation

There are many types of plasma waves in the Earth's magnetosphere. For decades it has been observed that ultra-low frequency electromagnetic ion cyclotron (EMIC) waves in the Pc 1-2 frequency range (0.1-5 Hz) near the ion cyclotron frequency are a prominent feature of the magnetosphere-ionosphere system. These waves play an important role in heating ionospheric ions to magnetospheric energies, regulating pressure anisotropy in the magnetosphere, populating the magnetosphere with energetic heavy ions during substorms, and inducing enhanced protons. EMIC waves are known to be excited as left-hand polarized waves near the magnetic equator in the inner magnetosphere and reach the ground propagating along the magnetic field line. Higher-frequency EMIC waves are often filtered during wave propagation to the ground, while lower-frequency EMIC waves can effectively reach the ground. Understanding this phenomenon is complicated because EMIC waves can be affected by various physical processes, the plasma environment along the propagation path in the magnetosphere/ionosphere, and wave properties. The team proposed to understand better the propagation and dissipation of EMIC waves using models and both space and ground-based observations. This collaborative research project consists of scientists from four institutes, including two non-R1 colleges. This project aims to investigate the propagation and dissipation of EMIC waves in the magnetosphere and ionosphere by answering these four scientific questions: 1. How do EMIC waves reach the ground?2. How is EMIC wave propagation affected by geomagnetic activity?3. How does geomagnetic field topology, such as compressed and stretched magnetic field, affect wave propagation?4. What is the significance of EMIC wave polarization in the context of the above parameters and how are wave polarizations related with propagation?The team will employ a state-of-art full-wave simulation code, Petra-M, which uses the finite element method (FEM). One advantage of using the FEM is that various magnetic field topologies and background plasma parameters are easily adopted in the simulation code. The Petra-M code will utilize realistic terrestrial magnetic field topologies (dipole and compressed magnetic field) and density configurations from empirical density models. Wave simulations will be performed to examine wave generation and propagation. The team will also analyze recent observations of these waves by multiple satellites and compare them with the ground magnetometer network observations. To consider the EMIC wave propagation in the inner magnetosphere, the proposers will investigate the following characteristics of the EMIC wave events between space (GOES satellite) and ground, spatial distribution (L and MLT), relationship with solar and geomagnetic activity, the distance between GOES satellites and plasmapause locations, and wave properties such as polarization, frequency, and normal angle. For the EMIC waves in the outer magnetosphere, the team will also investigate space (MMS, THEMIS, and Cluster)-ground conjugate observations using high-latitude ground stations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球磁层中有许多类型的等离子体波。 几十年来，已经观察到，在离子回旋频率附近的PC 1-2频率范围（0.1-5 Hz）中，超低频率电磁离子（EMIC）波是磁层离子层系统的重要特征。 这些波在将电离层离子加热到磁层能量，调节磁层中的压力各向异性，在磁层中调节压力各向异性，在磁层中用能量重离子填充磁层，并诱导增强的质子。 已知EMIC波被激发，因为内部磁层的磁赤道附近的左侧极化波，并沿着磁场线传播的地面。 在波传播到地面时，通常会过滤高频的EMIC波，而低频的EMIC波可以有效地到达地面。 理解这种现象是复杂的，因为EMIC波可能会受到各种物理过程的影响，磁层/电离层中传播路径的等离子体环境以及波性能。 该团队提议使用模型以及空间和基于地面的观测值更好地了解EMIC波的传播和耗散。 该协作研究项目由来自四个机构的科学家组成，其中包括两所非R1大学。该项目旨在通过回答这四个科学问题：1。如何到达地面？2。 emic波传播如何受地磁活性影响？3。地磁场拓扑（例如压缩和拉伸磁场）如何影响波传播？4。在上述参数的上下文中，EMIC波极化的意义是什么？与传播相关的波极化如何？该团队将采用最先进的全波模拟代码Petra-M，该代码使用有限元方法（FEM）。 使用FEM的一个优点是，在模拟代码中很容易地采用了各种磁场拓扑和背景等离子体参数。 PETRA-M代码将利用经验密度模型的逼真的地面磁场拓扑（偶极子和压缩磁场）和密度构型。 将进行波浪模拟以检查波浪产生和传播。 该团队还将通过多个卫星分析这些波的最新观察结果，并将其与地面磁力计网络观测值进行比较。 为了考虑内部磁层中的EMIC波传播，提议者将研究空间（卫星）和地面，空间分布（L和MLT）之间的EMIC波事件的以下特征，与太阳能和地磁活性，卫星和层状位置和诸如极性，频率，频率，频率，频率，频率和频率的距离之间的距离。 对于外部磁层中的EMIC波，该团队还将使用高纬度地面站研究空间（MMS，Themis和cluster） - 地面共轭观测值。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识绩效和更广泛影响的审查审查的标准来通过评估来通过评估来支持的。