Quantutative MHD Modeling of the Solar Transition Region Using Realistic Transport Coefficients

使用真实输运系数对太阳过渡区域进行定量 MHD 建模

• 批准号: 9816335
• 负责人: Michael Goodman
• 金额: --
• 依托单位: Catholic University of America
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-15 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9816335&HistoricalAwards=false
• 关键词: Quantutative; MHD; Modeling; Solar; Transition

ATM9816335absThe investigators will continue the development of a magnetohydrodynamic (MHD) model of the solar transition region. The transition region separates the solar chromosphere and the solar corona. It is a thin interface, a discontinuity, between the cooler, partially ionized chromosphere and the much hotter fully ionized corona. A large part of the extreme ultraviolet solar spectrum comes from the transition regions. In order to determine how the transition region is heated, it is necessary to combine observations with models that predict energy dissipation and thermal energy transport rates in the region of parameter space that describes the transition region. In an MHD model, this means that realistic expressions for the transport coefficients that determine resistive and viscous dissipation rates and thermal energy flux must be used, and evaluated, in the ranges of temperature, density, velocity, and magnetic field that characterize the transition region. Due to current limitations in computer speed, multi-dimensional, time dependent MHD simulations cannot use even remotely realistic values of these transport coefficients. The investigators will make modifications to an existing MHD model to include viscous effects, separate energy equations for electrons and protons, and a parametric representation of the net radiative loss in terms of electron temperature and density. The model will help resolve the controversy as to what degree the transition region is heated by in situ viscous dissipation, and dissipation of conduction and thermoelectric currents, as compared to the flux of thermal energy from the overlying corona

ATM9816335abs 研究人员将继续开发太阳过渡区域的磁流体动力学（MHD）模型。 过渡区将太阳色球层和日冕分开。 它是较冷的部分电离色球层和较热的完全电离日冕之间的薄界面，是一种不连续性。 极紫外太阳光谱的很大一部分来自过渡区域。 为了确定过渡区域如何被加热，有必要将观测结果与预测描述过渡区域的参数空间区域中的能量耗散和热能传输速率的模型相结合。 在 MHD 模型中，这意味着必须在表征过渡区域的温度、密度、速度和磁场范围内使用和评估确定电阻和粘性耗散率以及热能通量的输运系数的实际表达式。 由于当前计算机速度的限制，多维、时间相关的 MHD 模拟甚至无法使用这些传输系数的远程实际值。 研究人员将对现有的 MHD 模型进行修改，以包括粘性效应、电子和质子的独立能量方程，以及以电子温度和密度表示的净辐射损失的参数表示。 该模型将有助于解决与上层日冕的热能通量相比，过渡区域被原位粘性耗散、传导和热电流耗散加热的程度的争议