一、前言电离层物理学是地球物理学也是空间物理学中较老的一个分支学科。电离层是由于地球高层大气受太阳幅射作用而形成,似层状结构,故名电离层。它是一个近于电中性的等离子体介质,在其中传播的无线电波受到折射,反射,衰减等效应;临界频率就是电离层的等离子体频率,低于这一频率的电波被反射;而高于这一频率的电波则穿透而 I. INTRODUCTION Ionospheric physics is one of the older branches in geophysics and space physics. The ionosphere is due to the upper atmosphere of the Earth by the role of solar radiation formed, like layered structure, hence the name ionosphere. It is a near-neutral plasma medium in which the radio waves propagating are subject to refraction, reflections, decay, etc. The critical frequency is the ionospheric plasma frequency, and the waves below this frequency are reflected, while the high Waves at this frequency penetrate