Detection of plasma bubble in ionosphere using GPS receivers in Southeast Asia

Abstract

The equatorial ionosphere most often shows a nighttime plasma irregularity that is commonly referred as equatorial plasma bubble (PBB). The occurrence of PBB could cause rapid fluctuations in the amplitude and phase of the propagation radio signals and crucial to communication and navigation systems. The PBB normally occur successively where one structure rising after another during the sunset time. However, the onset time and location of the PBB are ubiquitous because the seed of the initial perturbation is not completely understood. Although various observation systems have been developed to capture the EPB, each of the measurement is limited with space and time resolution. This study aims to observe 2D structure of the PBB using high-density GPS receivers in Southeast Asia. GPS data was collected from 127 GPS receivers in Southeast Asia with the spacing distances of 30-120 km from each other. Total electron content (TEC) was derived from the difference between two signals from each GPS satellite. The signature of the PBB was detected using rate of TEC change index (ROTI) for all the available satellites to receiver paths. The 2D structure of the PBB was obtained by averaging GPS ROTI into 0.45° latitude × 0.45° longitude grid and projected at 300 km altitude. A case study on the night of 18 Mac 2011 showed the births of six PBB structures during the passage of the solar terminator along the 95°E to 120°E longitude. The separation distance between the PBB structures varied from 300 to 600 km. The separation distance between the EPB structures play an important role in determining the source of the seeding mechanism that believed in a form of wavelike structure.