Resonant Infrasonic Disturbances in Total-Electron-Content During a Severe Thunderstorm on 23 October 2021

Abstract

Deep convective clouds and lightning activity during thunderstorms imprint Infrasonic ($>$3 mili Hertz) oscillations in the ionospheric density or Traveling Ionospheric Disturbances (TIDs). The wave characteristics of these oscillations and the coupling mechanisms remain a subject of investigation, noting that the coupling energetics may alter the spectral and propagation characteristics. Moreover, the availability of numerous convective dynamics time scales makes the oscillation detection time uncertain. To study these aspects, the present work examines the spatial-temporal lightning flash rate during a severe thunderstorm (cloud top temperature −80°C) from the GOES16 infrared channel and the total electron content of the ionosphere from the GNSS network over the tropical Southern Hemisphere. The study finds TIDs amplification above the deep convective clouds. The strongest amplification occurs at the earliest, at 9 min, from the most intense lightning flash rate and propagates at the most probable speed of 400–1,100 m/s. In contrast to the spectral peak of the active storm, which is 1.2 mHz, the spectral peak of TIDs is 4.8 mHz. The results highlight the magnitude of coupling energetics to determine the wave propagation characteristics of infrasonic TIDs.