Equatorial plasma bubble zonal drift velocity variations in response to season, local time, and solar activity across Southeast Asia

Abstract

This work investigated the zonal drift velocity, VE, of equatorial plasma bubbles (EPBs) which was calculated from the zonal keogram of the rate of total electron content index obtained using the Global Positioning System data from the Malaysia Real-Time Kinematics GNSS Network over Southeast Asia across the period 2008 until 2013 (498 nights). In general, a long-term study on the VE of EPBs and its dependence on the season, local time, and solar activity over Southeast Asia by using Global Positioning System multipoint receivers has never been conducted before. The case study showed that the VE estimated from Malaysia Real-Time Kinematics GNSS Network was basically within a similar range to that of the 630-nm airglow images obtained at Kototabang, Indonesia. Furthermore, the VE of EPBs was higher during high solar-activity period, which was in line with past studies. The time range of the EPB VE peak is more accurately determined compared to previous studies. In high solar activity conditions, a peak of VE was observed at 2130 LT (equinox), 2200 LT (June solstice), and after 2300 LT (December solstice). After this peak, the EPB VE steadily decreased with time during the equinox and was varied throughout the night during June solstice. Moreover, it was found to differ with time from the evening to the postmidnight period during December solstice.