# Detection of acoustic-gravity waves in lower ionosphere by VLF radio waves

## TL;DR

This paper introduces a novel amplitude analysis method for detecting harmonic acoustic and gravity waves in the lower ionosphere using VLF radio wave reflections, revealing their global presence and dynamics.

## Contribution

The paper presents a new real-time amplitude analysis technique to study ionospheric waves via VLF radio wave reflection, highlighting their global oscillatory nature.

## Key findings

- Detection of acoustic and gravity waves in the lower ionosphere.
- Confirmation of global oscillation patterns at different atmospheric heights.
- Identification of wave periods corresponding to known atmospheric oscillations.

## Abstract

We present a new method to study harmonic waves in the low ionosphere (60 - 90 km) by detecting their effects on reflection of very low frequency (VLF) radio waves. Our procedure is based on amplitude analysis of reflected VLF radio waves recorded in real time, which yields an insight into the dynamics of the ionosphere at heights where VLF radio waves are being reflected. The method was applied to perturbations induced by the solar terminator motions at sunrises and sunsets. The obtained results show that typical perturbation frequencies found to exist in higher regions of the atmosphere are also present in the lower ionosphere, which indicates a global nature of the considered oscillations. In our model atmosphere, they turn out to be the acoustic and gravity waves with comparatively short and long periods, respectively.