The Earth's ionosphere, extending about 80 to 1,000 km above the Earth's surface, connects the outer space and the middle atmosphere. It's an important part and key layer in the whole Sun-Earth system.

However, the understanding of the equatorial ionospheric responses to thunderstorms remains a mystery due to the peculiarities in the dynamics of the ionosphere over this region.

In a recently published study in Scientific Reports, the Congo Basin, located in the equatorial region, is studied because the lightning and severe thunderstorms in the region are considered to be the most active all over the world.

In the study, Dr. Babalola Ogunsua, a postdoctoral fellow from Nigeria with Prof. QIE Xiushu's research group from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences traced the thunderstorm effect through ground-based World Wide Lightning Location Network (WWLLN) observations, in combination with the ionospheric total electron content (TEC) measured from the communication path between the Global Positioning System (GPS) satellite and the GPS receiver station in the West Africa-Congo basin.

The researchers found solid evidence of tropospheric thunderstorms' impact on the ionospheric electron content. Ogunsua said, "We found that changes in the ionospheric electron content resulting from thunderstorms propagated from the location of the thunderstorm to a specific direction, with high peaks of the total electron content deviation, and the gravity waves induced by thunderstorms oscillated between 16 and 76 minutes."

 An illustration of the atmospheric wave dynamics from convective processes and ionospheric responses (Image by Babalola Ogunsua)  

"The dynamics of the equatorial ionosphere are suppressed by the impact of thunderstorm activity during the day with visible gravity wave effects, and the effect of the gravity wave is negligible at night due to the plasma bubbles and large scale TEC deviation," said Prof. QIE.

This study provides a better understanding of the equatorial ionosphere in terms of its responses to extreme tropospheric events, with additional information for improved modeling of the equatorial ionosphere.