Theoretical Study of Ground-Based Auroral Radio Emissions

该项目的目标是解决几个关键的理论问题，这些问题与在地面上观测到的从5kHz到5MHz的无线电波频率范围有关，这些无线电波被称为极光咆哮。在美国国家科学基金会之前的支持下，PI和他的同事们能够为两种类型的排放提供基本的解释-连续的咆哮是在F区域源附近的密度耗尽中产生的，而离散的咆哮是密度增强的特征模态。这两种类型的发射的一个关键共同因素是产生上层混合波或Z模波，并将其转换为电磁波。以往的研究项目主要集中在表征和理解上杂化/Z模波的产生过程。提出的研究重点将放在Z模波到电磁波的转换和/或耦合上。这样的研究是必要的，把连续和离散的咆哮排放理论在一个完全可行的基础上。

The objective of the project is to address several key theoretical issues relevant to the frequency-range from 5kHz to 5MHz radio waves observed on the ground in the auroral zone, known as auroral roars. With the previous support from NSF, the PI and his colleagues were able to provide basic explanations for two types of emissions - the continuum roars are generated within the density depletion near the F -region source, while the discrete roars are eigenmodes of density enhancements. A key ingredient common to both types of emissions are the generation of upper-hybrid, or Z -mode waves, and their conversion to electromagnetic waves. The previous research project was largely concerned with the characterization and understanding of the generation process of upper-hybrid/Z -mode waves. The focus of the proposed research will be on the conversion and/or coupling of Z -mode waves to electromagnetic waves. Such a study is essential to put the theories of continuum and discrete roar emissions on a fully viable footing.