Typical comparisons between plasma bubble and blob distributions at different altitudes over the Indian sector using a unique combination of satellite-based observations – a case study

Abstract

We report in this article, for the first time, on the altitudinal variations of ionospheric irregularities during post-sunset hours between 14 and 17 October 2001 at Indian longitudes by using a unique combination of Challenging Mini Satellite Payload (CHAMP), Republic of China Satellite (ROCSAT-1), and Defense Meteorological Satellite Programme (DMSP) satellites located at about 400, 650, and 850 km, respectively. It became possible for us to study the width of plasma bubbles and plasma blobs in the longitudinal (zonal) direction at different altitudes along with temporal variations of ion velocity components in horizontal (Vy) and vertical (Vz) directions as probed by ROCSAT-1 and DMSP satellites. The dominant features noticed in Vy and Vz components are their anti-correlation relationship at the ROCSAT-1 satellite’s altitude (mirroring effect). The most important observation from this study is that plasma bubbles are found to have occurred immediately after post-sunset hours, whereas plasma blobs were observed after three hours following the bubbles’ appearance time and continued until pre-sunrise hours at higher altitudes between around ±5° and ±20° from the magnetic equator, which indicate that the plasma blobs emanate from plasma bubbles that generated at the bottomside of the ionospheric F-layer shortly after sunset on similar lines to a few recent research studies. It is therefore believed that the polarized electric fields generated inside plasma bubbles might have played a role in the generation of higher-altitude plasma blobs. Importantly, the calculated power spectra of bubbles and blobs show a nearly equal trend, indicating that they are intricately connected with each other.