M-I Coupling: Physics Based Algorithm for the High Latitude Conductance and Its Implications

M-I耦合：基于物理的高纬度电导算法及其意义

• 批准号: 0334615
• 负责人: Konstantinos Papadopoulos
• 金额: $ 12万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-02-15 至 2007-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0334615&HistoricalAwards=false
• 关键词: Coupling; Physics; Based; Algorithm; Latitude

The objective of this research is to develop a physics-based module of the ionospheric conductivity that incorporates anomalous heating due to the electrojet instability driven by strong convection electric fields in the ionosphere. Reliable dynamic ionospheric conductance and energy dissipation modules covering the entire range of the solar wind input are critical elements in the construction of global electrodynamic ionosphere-magnetosphere models, such as the Geospace General Circulation Model (GGCM), the Global Ionospheric Model (GIM) and the TIME-GCM Model. Furthermore, they are critical in the representation of the ionospheric boundary in global magneto-hydrodynamic codes. A semi-empirical model based on a simple prescription is used in the LFM model, while an assimilation model, the Assimilating Mapping of Ionospheric Electrodynamics (AMIE) is the frontrunner for incorporation to the GGCM. The modeling and comparison with data shows that the above models perform well under conditions of moderate ( 20 mV/m) local ionospheric electric fields. Under strong ( 20 mV/m) local ionospheric electric fields, an important energy dissipation mechanism due to the electron Hall current becomes important. This process is not included in the traditional ionospheric electrodynamic energy budget, since the current and the electric field are orthogonal to each other. The dissipation is thus anomalous and is attributed to well known and experimentally documented Farley-Buneman two-stream electrojet instability. Electron temperatures in excess of 2000 K have been observed by the EISCAT radar and earlier by the Chatanika radar at E-region altitudes. The process, in addition to acting as a non-Ohmic dissipation, results in changes in the Pederson and Hall conductances by modifying the electron recombination coefficient and thus increasing the resultant plasma density. In this study, appropriate algorithms will be developed for incorporation in the AMIE, GIM, TIME-GCM and to global MHD codes. The new conduction module will be disseminated to the broader space science community to assess its ability to represent the observed saturation of the polar cap potential. The most challenging aspects of this research are the treatment of cross scale coupling and the incorporation of collisionless microphysics effects into fluid and electrodynamic models in the form of anomalous transport. The study will expose students to interdisciplinary research because it involves computer simulations and modeling with applications to fusion and plasma physics, meteorology, and overall to studies of complex physical and biological systems.

这项研究的目的是开发一个基于物理学的电离层电导率模块，其中包括由于电离层中强对流电场驱动的电射流不稳定性引起的异常加热。可靠的动态电离层电导和能量耗散模型覆盖太阳风输入的整个范围，是建立全球电动力电离层-磁层模式的关键要素，如地球空间环流模式（GGCM）、全球电离层模式（GIM）和TIME-GCM模式。此外，他们是至关重要的电离层边界的全球磁流体动力学代码的表示。一个半经验模式的基础上的一个简单的处方中使用的LFM模式，而同化模式，电离层电动力学的同化映射（AMIE）是领跑者纳入GGCM。模拟和数据比较表明，上述模型在中等（20 mV/m）的电离层局部电场条件下具有较好的性能。在强（20 mV/m）的局部电离层电场下，由于电子霍尔电流的重要能量耗散机制变得重要。这个过程不包括在传统的电离层电动能量预算中，因为电流和电场彼此正交。因此，耗散是异常的，并归因于众所周知的和实验记录的Farley-Buneman双流电射流不稳定性。电子温度超过2000 K已经被EISCAT雷达和更早的Chatanika雷达在E区高度观测到。该过程，除了作为一个非欧姆耗散，结果在佩德森和霍尔电导的变化，通过修改电子复合系数，从而增加了所得的等离子体密度。在这项研究中，适当的算法将被开发纳入AMIE，GIM，TIME-GCM和全球MHD代码。新的传导模块将分发给更广泛的空间科学界，以评估其表示观测到的极冠电位饱和度的能力。这项研究的最具挑战性的方面是跨尺度耦合的治疗和将无碰撞的微观物理效应纳入流体和电动力学模型的异常传输的形式。这项研究将使学生接触到跨学科的研究，因为它涉及计算机模拟和建模，应用于融合和等离子体物理学，气象学，以及复杂的物理和生物系统的研究。