Propagation of waves in the middle and upper atmosphere excited by intense events at the earth’s surface and lower atmosphere

Severe events in the Earth's surface and lower atmosphere—such as volcanic eruptions, earthquakes, typhoons, thunderstorms, and anthropogenic explosions—can excite various types of waves. These waves propagate into the middle/upper atmosphere and ionosphere in the form of acoustic and gravity waves, exerting significant impacts on these regions. Such events provide typical case studies for investigating the physical mechanisms of coupling between Earth's various spheres. This paper reviews the observational and research findings of Professor Xiao Zuo's team regarding the effects of severe events like earthquakes and typhoons on the ionosphere. The paper also highlights the establishment of a dual-layer airglow observation network over China and the utilization of this detection system to study the propagation characteristics and effects of gravity waves excited by events such as volcanic eruptions, typhoons, and thunderstorms in the middle/upper atmosphere and ionosphere. The research results reveal that although gravity waves generated by volcanic eruptions cannot propagate directly over long distances in the middle and upper atmosphere, they can achieve extensive and long-range transmission through ocean-atmosphere interactions. The background atmospheric structure plays a crucial role in gravity wave propagation, with atmospheric waveguides enabling anomalous long-distance propagation of gravity waves. Although small- to medium-scale gravity waves have difficulty directly propagating upward to the thermosphere, secondary wave mechanisms can effectively facilitate their propagation from the middle atmosphere to the upper atmosphere. Furthermore, studies on typhoon events provide direct observational evidence of how severe lower atmospheric events influence the upper atmosphere and ionosphere.