Collaborative Research: Theory and Numerical Simulations of Intermittent Turbulence in Geospace

合作研究：地球空间间歇湍流的理论和数值模拟

• 批准号: 0637400
• 负责人: Tom Chang
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0637400&HistoricalAwards=false
• 关键词: Collaborative; Research; Theory; Numerical; Simulations

This project will quantitatively address the phenomenon of intermittent turbulence in geospace, with particular emphasis placed on the multifractal nature of the plasma fluctuations observed in the magnetotail and plasma sheet. Detailed spectra and other stochastic properties will be deduced and evaluated from first principles both theoretically and numerically. These results will be compared with actual in-situ experimental observations using modern statistical methods. The sporadic and localized interactions of magnetic coherent structures arising from the plasma resonances can be the source for the observed intermittent turbulence in geospace. Power spectra and local intermittency measures using wavelet analyses will be calculated to display the spottiness of the small-scale turbulent fluctuations and the non-uniformity of coarse-grained dissipation that can lead to magnetic topological reconfigurations. The technique of the dynamic renormalization group will be applied to the study of the scaling properties of the multifractal fluctuations. The structure functions and singular spectra will being quantitatively evaluated in detail and compared with the results obtained from actual experimental observations.

该项目将定量地解决地球空间中间歇性湍流现象，特别强调在磁尾和等离子体片中观察到的等离子体波动的多重分形性质。详细的光谱和其他随机性质将从理论和数值上的第一性原理推导和评估。这些结果将与使用现代统计方法的实际现场实验观测结果进行比较。等离子体共振引起的磁相干结构的偶发和局域相互作用可能是地球空间中观测到的间歇性湍流的来源。利用小波分析计算功率谱和局部间歇度量，以显示小尺度湍流波动的斑点性和可能导致磁拓扑重构的粗粒度耗散的不均匀性。将动态重整化群技术应用于多重分形波动的标度性质研究。对结构函数和奇异谱进行了详细的定量评价，并与实际实验观测结果进行了比较。