GEM: Modeling of Magnetosphere-Ionsophere Coupling (MIC) at High and Mid-Latitudes

磁层和电离层的耦合是高纬度和中纬度磁层动力学的一个关键问题。关于这种动态的大部分可用信息来自地面磁力计阵列和电离层雷达，它们可以对这些过程进行多点观测。该项目将模拟电磁能量通过该系统的传播，以更好地理解磁层和电离层过程与地面观测到的特征之间的关系。本研究中使用的主要工具是线性三维磁流体动力学（MHD）波建模代码，该代码以非正交偶极子坐标投射，以便更好地模拟磁层场线的较低海拔部分。该代码已成功地用于模拟Pc1脉冲通过电离层波导的传播和Pc3在日侧磁层场线共振的形成。该代码是对描述外磁层对流的全球MHD模型和模拟内磁层热粒子对流的Rice对流模型（RCM）的补充。因此，它将有助于更好地理解低海拔地区的电动力学磁层-电离层耦合过程，而其他两种模式都没有很好地涵盖这一过程。波模拟代码非常适合于比较磁层和电离层不同点的观测结果。因此，该项目将比较卫星、电离层雷达和地面磁力计的数据与模型的结果。研究将集中在三个方面：(1)极低频波在等离子层中的传播；(2)磁暴期间高纬度和中纬度电场之间的耦合；(3)电离层响应场向电流的反馈动力学。这些问题中的第一个将涉及扩展目前可用的代码，以包括电离层的动力学。这些扩展已经包含在代码的简单版本中。第二个和第三个问题将受益于模型的改进，其中电离层密度和电导率在所有三个维度上都是变化的，包括昼夜不对称性和等离子层密度随当地时间的变化。这项工作将主要由研究生完成，他们将接受科学计算艺术方面的训练，以及解释数值结果以及卫星、雷达和地面磁力计获得的数据所必需的物理理解。此外，该工作将通过开发可集成到地球空间环流模型（GGCM）的磁层-电离层耦合模型，为地球空间环境建模（GEM）计划服务。

The coupling of the magnetosphere and ionosphere is a critical problem to the dynamics of the magnetosphere at both high and mid-latitudes. Much of the information that is available about this dynamics comes from arrays of ground magnetometers and ionospheric radars that can give multi-point observations of these processes. This project will model the propagation of electromagnetic energy through this system to better understand the relationship between magnetospheric and ionospheric processes and the observed signatures on the ground. The main tool to be used in this investigation is a linear three-dimensional Magneto-HydroDynamics (MHD) wave modeling code that has been cast in non-orthogonal dipole coordinates in order to better model the lower altitude parts of magnetospheric field lines. This code has been successfully used to model of the propagation of Pc1 pulsations through the ionospheric waveguide and the formation of Pc3 field line resonances in the dayside magnetosphere. This code is complementary to both global MHD models that describe convection in the outer magnetosphere and to the Rice Convection Model (RCM) that models hot particle convection in the inner magnetosphere. As such, it will be useful as a means to better understand the electrodynamic magnetosphere-ionosphere coupling processes at low altitudes that are not well covered by either of these other two models. The wave modeling code is well suited to comparing observations at various points in the magnetosphere and ionosphere. Thus, the project will compare date from satellites, ionospheric radars, and ground magnetometers with the results from the model. The research will focus on three specific topics: (1) The propagation of ULF waves in the plasmasphere, (2) the coupling between electric fields at high and mid-latitudes during magnetic storms, and (3) The feedback dynamics of the ionosphere in response to field-aligned currents. The first of these problems will involve the extension of currently available code to include the dynamics of the ionosphere. These extensions have already been included in simpler versions of the code. The second and third problems will benefit from model improvements in which the ionospheric density and conductivity are varied in all three dimensions, including day-night asymmetry and the variation of plasmasphere density with local time. This work will largely be done by graduate students, who will be trained in the art of scientific computation as well as the physics understanding necessary to interpret the results of not only the numerical results but also the data obtained by satellites, radars, and ground magnetometers. In addition, the work will serve the purposes of the Geospace Environment Modeling (GEM) program by developing a magnetosphere-ionosphere coupling model that can be integrated into a Geospace General Circulation Model (GGCM).