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

该项目将为地球空间环境模型(GEM)地球空间环流模式(GGCM)开发辐射带模块(RBM)。RBM将促进我们对高能电子非绝热动力学的理解的重大进展，因为将首次同时评估影响辐射带电子的所有主要物理过程。RBM将由内部磁层的耦合赖斯对流模型(RCM)和描述全球磁层的磁流体动力学(MHD)代码驱动。因此，它将提供仅根据太阳扰动预测辐射带变化的能力。在无碰撞的磁层环境中，波粒相互作用提供了俯仰角散射、能量扩散和异常跨场输运的主要机制。目前对这类过程的理解已经成熟到可以构建现实的量化模型的程度。在RBM中，这样的过程将根据预期的散射波功率谱密度，通过三维扩散系数来量化。径向扩散率将由MHD程序模拟的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，将发展一个全球VLF波和EMIC波分布的参数化方案。拟线性扩散代码将用于评估全球范围内的俯仰角散射率和能量扩散率。三维扩散方程的数值积分将提供辐射带电子对太阳扰动的响应的模拟。这项拟议的研究是2002年NRC十年报告中的三项挑战的核心：(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力学反应，(2)了解在太阳和空间等离子体中观察到的过程中体现的基本物理原理，以及(3)发展近实时预测能力，以了解和量化太阳、行星际介质和地球磁层的动力过程对人类活动的影响。加州大学洛杉矶分校的可视化门户设施将被用来构建风暴期间辐射带电子变化的3D电影。这项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中，并将在加州大学洛杉矶分校为研究生提供的可视化门户网站上展示。

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.