Evolution of plasma bubbles over Vietnam region observed using the CERTO beacon on board C/NOFS satellite

Abstract

Observation of evolution of plasma bubbles using the ground based reception of Coherent Electromagnetic Radio Tomography (CERTO) beacon signals from the Communications/Navigation Outage Forecasting System (C/NOFS) satellite on 25 January 2009 are presented. These observations are made from Bac Lieu, Vietnam (9.2°N, 105.6°E geographic, 1.7°N magnetic dip latitude). The ionosonde observations from Bac Lieu and Chumphon (10.7°N, 99.4°E, 3.3° magnetic dip latitude) show that there is a well developed equatorial spread-F (ESF) at 105°E longitude, whereas ESF was absent at 99°E longitude. Hence, the successive passes of C/NOFS reveal the evolutionary phases of plasma irregularities over 105°E longitude. This also enables to observe the corresponding VHF and UHF scintillations at their different phases of evolution and gives a measure of the spectral evolution of irregularities. The spectral characteristics obtained from successive passes bring out the signatures of the cascading process. This example shows the patchy nature of the ESF irregularities and the longitudinal variability of ESF during the deep solar minimum period.