Investigation of the possible dependence of equatorial plasma bubble with travelling ionospheric disturbances using airglow-imager at Abuja

Abstract

Airglow images obtained with the aid of a ground-based Airglow Imager (AGI) located at Abuja, Nigeria (Geographic: 7.39°E, 8.99°N; Dip latitude: −1.60°) have been used to study the possible relationship between the occurrence of Atmospheric Gravity Waves (AGWs) and Equatorial Plasma Bubbles (EPBs) to investigate the role AGW plays in the occurrence of EPB. Airglow images covering over two and half years (nighttime only), from June 2015 to August 2018 were used. Three filters of the airglow imager were used in this study, taking observation over 652 days (nights). Results show that AGW occurrence is random with no regular trend and very rare at the station compared with EPB. EPB is found to occur more frequently with local time and seasonal dependence. Peak occurrences of EPB are observed during the equinoctial months. Although concurrent occurrences of the two phenomena are very infrequent, results further show that whenever both phenomena occur simultaneously, the duration of occurrences tends to suggest there exists a relationship between them. The concurrent occurrence of the two phenomena is observed more during post-sunset than post-midnight hours whenever it happens. Although EPB occurs independently of AGW, the results show that on nights where we have concurrent occurrences, EPB occurrence tends to take place earlier than days of EPB occurrence without AGW. We, therefore, conclude from the results obtained in this study that, AGW is not the only factor that contributes to the occurrences of EPB at the station since the AGW observed might not have consistently propagated to the bottomside of the F layer due to its dissipation. However, whenever it occurs, AGW tends to influence the conditions that trigger the occurrence of EPB.