On the Characteristics and Dynamics of Evolving and Non-Evolving Equatorial Plasma Bubbles using Ionosonde Observations

This study investigates the characteristics of an evolving (active) and non-evolving (fossil) equatorial plasma bubbles (EPBs) using Digital Ionosonde located at an equatorial station, Tirunelveli (8.7 °N, 77.8 °E; Dip: 1.7 °N), India. The study compares “active” (evolving) bubbles and “fossil” (decaying) bubbles. Active bubbles contain large structures that break down into smaller irregularities as they develop. In contrast, fossil bubbles mainly consist of large-scale structures and move more steadily through the ionosphere. It was found that active bubbles are influenced by polarization electric fields, which makes their motion irregular and difficult to measure accurately. However, once these electric fields weaken, the fossil bubbles move smoothly with the surrounding plasma. Because of this, fossil bubbles can be used to better estimate how the ionospheric plasma is zonally drifting. The study also shows the importance of distinguishing between EPBs that form locally and those that drift in from elsewhere. This study helps to improve the prediction of signal disruptions in communication and navigation systems that depend on the ionosphere.