Significant Day-time Ionospheric Perturbation by Thunderstorms along the West African and Congo Sector of Equatorial Region

B O Ogunsua,D Wang,R Jiang,J Yang,X Qie,J Bian,A Srivastava

doi:10.1038/s41598-020-65315-3

Abstract

The equatorial Congo has been recognized as the most active lightning chimney region in the Globe. Although the perturbation of tropospheric thunderstorms on the lower ionosphere has been noticed in the middle latitudes through their transient lightning electric fields or convective gravity waves, the effects on equatorial ionosphere and the horizontal extent of this perturbation remains a mystery because of the difficulties in extracting the effects due to the sporadic nature of the equatorial ionosphere. Here we present observational results showing solid evidence of deviations in ionospheric total electron content (TEC) and its direction of propagation associated with thunderstorms using the method of polynomial filtering, by utilizing the TEC measured from equatorial Global Positioning System (GPS) Receiver stations along the West African region-Congo Basin. The TEC deviations due to the thunderstorms were found to be mostly propagated in a specific direction from the point of the event, with the highest absolute peak TEC at ~±1.5 TECUs. The internal dynamics of the equatorial ionosphere have been found to be suppressed by large thunderstorm effects during the daytime, with negligible impact at night.

Highlights

The ionosphere is a system that can be dynamically perturbed, due to the direct external influences from solar dynamics and activities
We hereby focus on the following points of inquiry: The first point of inquiry is on how evident the total electron content (TEC) deviations are, due to thunderstorms at the equatorial regions, considering the high TEC gradients which are peculiar to the equatorial ionosphere especially at night
The results presented in this work show the TEC deviations for some Global Positioning System (GPS) TEC stations located within the region of the selected thunderstorm events, compared with other stations visible to the same GPS satellites at various distances from the point of thunderstorm event

Summary

Introduction

The ionosphere is a system that can be dynamically perturbed, due to the direct external influences from solar dynamics and activities (such as geomagnetic storms and solar radiations events). The study of the effect of thunderstorms on the African equatorial sector of the ionosphere is very important but challenging considering the peculiarities of the dynamics of the equatorial ionosphere, as the equator is generally known for a high degree of irregularities and high magnitude TEC gradients most especially at nighttime These irregularities could be associated with plasma depletion, plasma bubbles from spread F and sporadic E layer disruption or its formation with instabilities during pre-reversal enhancements (PRE) periods and other Rayleigh-Taylor instability based irregularities. We considered the nighttime responses for the purpose of comparison and validation

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Results

Conclusion