Theoretical Studies on Ionospheric Irregularities and Plasma Instabilities in the Magnetosphere

这笔赠款支持有关电离层和磁层物理物理的若干方面的工作。为赤道电离层开发的湍流模型将扩展到更复杂的极地电离层几何形状。沿极地磁场的密度梯度可能会使极地电离层中的湍流变得更加三维，而不是之前所认为的二维。对极地电离层不规则的雷达后向散射谱的观测证明了这一点。此外，还将就极地电离层中报告的电子异常加热问题开展工作。由于极地电离层中存在很高的电场，由PI和其他人发展的现有理论需要重新检查，以包括非线性效应。第三个项目将解决漂移波和E×B湍流的重整化群分析。最近发展了一种利用重整化群分析(RNG)来研究完全发展湍流的有力工具。其中一个重要的应用是推导用于数值计算的亚格子模型的精确算法。在地球物理尺度长度问题的一组偏微分方程组的任何数值计算中，自由度都非常大，即使在最大的超级计算机上进行实际计算，自由度也必须大大减少。核心问题是如何在不丢失基本物理学的情况下进行这样的减少。在另一个项目中，PI已经开发了一个基于RNG的Alfven波湍流亚网格模式。对于电离层物理，国际电离层研究所正在开发基于RNG的漂移波湍流和E×B湍流的亚网格模式，这些湍流普遍存在于E和F区域。

This grant supports work on several aspects of ionospheric and magnetospheric physcis. Turbulence models developed for the equatorial ionosphere will be extended to the more complex geometry of the polar ionosphere. The density gradient along the polar magnetic field is likely to make the turbulence in the polar ionosphere more 3-dimensional rather than 2-dimensional considered earlier. This is borne out by observations of the radar backscattered spectrum of the irregularities in the polar ionosphere. In addition, work will be done on the anomolous heating of electrons reported in the polar ionosphere. Because of the high electric fields present in the polar ionosphere existing theories developed by the PI and others require re- examination to include nonlinear effects. A third project will address renormalization group analysis of drift-wave and E x B turbulance. A powerful tool employing renormalization group analysis (RNG) has been recently developed for the study of fully developed turbulence. One of the important applications is the derivation of exact algorithms for subgrid modelling for numerical computation. In any numerical computation of a set of partial differenial equations for a problem on the geophysical scale length, the degrees of freedom are enormously large and freedom must be severely reduced for actual computation on even the largest supercomputers. The central issue is how to make such a reduction without losing the essential physics. In connection with another project the PI has already developed a RNG based subgrid model for Alfven wave turbulence. For ionospheric physics, the PI is developing RNG based subgrid models for drift-wave turbulence and E x B turbulence prevalent in E and F regions.