Influence of the Earth's atmosphere rotation on the spectrum of acoustic-gravity waves

TL;DR

This paper investigates how Earth's atmospheric rotation, considering both horizontal and vertical components, influences the spectrum and propagation boundaries of acoustic-gravity waves, highlighting the dominant role of the vertical component.

Contribution

It extends previous work by analyzing the combined effects of horizontal and vertical rotation components on acoustic-gravity waves, emphasizing the vertical component's dominant influence.

Findings

Vertical rotation component significantly affects gravity wave lower limits.

Horizontal component causes negligible modifications to wave boundaries.

Lower limit of gravity waves depends on latitude, equal to 2Ωsinφ.

Abstract

It was shown in a recent paper by Cheremnykh et al. (Advances in Space Research, 2022) that taking into account the rotation of the Earth's atmosphere leads to the appearance of a new region of evanescent waves with a continuous frequency spectrum on the diagnostic diagram of acoustic-gravity waves. The region is located below the lower limit of gravity waves, which is equal $2\Omega$ at all wavelengths, where $\Omega$ is the angular frequency of the atmosphere rotation. This result was obtained for high-latitude regions of the atmosphere, in which we can limit ourselves to considering only the vertical component of the Earth's rotation frequency. In the proposed paper we show that taking into account both components of the vector of the atmosphere rotation frequency $\overrightarrow{\Omega}$ - horizontal, $\Omega\cos\varphi$ , and vertical, $\Omega\sin\varphi$, where $\varphi$ is the Earth`s latitude, the dominant role in the acoustic-gravity waves propagation is played by the vertical component. It is shown that the horizontal component leads to an insignificant modification on the diagnostic diagram of the boundaries of the areas of acoustic and gravity waves, which can be neglected. Also shown that the strongest vertical component of the frequency affects the lower limit of gravity waves, which depends at all wavelengths on the latitude of the observation site and is equal to $2\Omega\sin\varphi$.