GEM: Development of a Three-dimensional (3-D) Diffusion Code as a Radiation Belt Module in the Geospace General Circulation Model (GGCM)

GEM：开发三维 (3-D) 扩散代码作为地球空间环流模型 (GGCM) 中的辐射带模块

• 批准号: 0603191
• 负责人: Yuri Shprits
• 金额: --
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-15 至 2010-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0603191&HistoricalAwards=false
• 关键词: GEM; Development; Three; dimensional; Diffusion

This project will develop a Radiation Belt Module (RBM) for the Geospace environment Modeling (GEM) Geospace General Circulation Model (GGCM). The RBM will facilitate a major advance in our understanding of energetic electron non-adiabatic dynamics, since, for the first time, all dominant physical process, which affect radiation belt electrons, will be simultaneously evaluated. The RBM will be driven by the coupled Rice Convection Model (RCM) of the inner magnetosphere and magnetohydrodynamic (MHD) codes to describe the global magnetosphere. It will consequently provide the capability of predicting changes in the radiation belts based solely on solar disturbances. In the collisionless magnetospheric environment, wave particle interactions provide the dominant mechanism for pitch-angle scattering, energy diffusion and anomalous cross-field transport. The current understanding of such processes has now matured to a level where realistic quantitative models can be constructed. In the RBM, such processes will be quantified by 3-D diffusion coefficients, based on the anticipated power spectral density of scattering waves. Radial diffusion rates will be obtained from the properties of ULF waves simulated by the MHD code. A parameterization scheme for the global distribution of VLF waves and EMIC waves will be developed, based on the flux of injected ring current electrons and ions provided by the RCM. A quasi-linear diffusion code will be used to evaluate the rates of pitch-angle scattering and energy diffusion on a global scale. Numerical integration of the 3-D diffusion equation will provide a simulation of the response of radiation belt electrons to solar disturbances. The proposed study is central to three challenges in the 2002 NRC Decadal report: (1) Understanding the space environment of Earth and other solar system bodies and their dynamical response to external and internal influences, (2) Understanding the basic physical principals manifest in processes observed in solar and space plasmas, and (3) Developing near real-time predictive capability for understanding and quantifying the impact on human activities of dynamical processes at the Sun, in the interplanetary medium, and in the Earth's magnetosphere. The UCLA Visualization Portal facilities will be used to construct 3-D movies of the variability of radiation belt electrons during storms. Results from the study will be integrated into courses for a new Collaborative Laboratory and Space Plasma Physics Interdisciplinary Degree Program at UCLA, and will be shown at UCLA visualization portal for graduate students.

本项目将为地球空间环境建模（GEM）和地球空间环流模型（GGCM）开发一个辐射带模块（RBM）。RBM将有助于我们对高能电子非绝热动力学的理解取得重大进展，因为这是第一次，所有影响辐射带电子的主要物理过程将同时得到评估。RBM将由内部磁层的Rice对流模型（RCM）和磁流体动力学（MHD）代码耦合驱动，以描述全球磁层。因此，它将提供仅根据太阳扰动预测辐射带变化的能力。在无碰撞磁层环境中，波粒相互作用是俯仰角散射、能量扩散和异常跨场输运的主要机制。目前对这些过程的理解已经成熟到可以构建现实的定量模型的程度。在RBM中，基于散射波的预期功率谱密度，这些过程将通过三维扩散系数来量化。径向扩散率将由MHD代码模拟的ULF波的性质得到。基于RCM提供的注入环电流电子和离子的通量，提出了VLF波和主位波全局分布的参数化方案。拟线性扩散代码将用于在全球范围内评估俯仰角散射和能量扩散的速率。三维扩散方程的数值积分将提供辐射带电子对太阳扰动响应的模拟。拟议的研究是2002年NRC十年报告中三个挑战的核心：(1)了解地球和其他太阳系天体的空间环境及其对外部和内部影响的动态响应；(2)了解在太阳和空间等离子体中观测到的过程中体现的基本物理原理；(3)发展接近实时的预测能力，以了解和量化太阳、行星际介质和地球磁层的动态过程对人类活动的影响。加州大学洛杉矶分校可视化门户设施将用于构建风暴期间辐射带电子变化的3d电影。该研究的结果将被整合到加州大学洛杉矶分校新的合作实验室和空间等离子体物理跨学科学位课程的课程中，并将在加州大学洛杉矶分校的研究生可视化门户网站上显示。