Observation and analysis of plasma bubbles in Hainan during the magnetic storm in March 2015

The ionospheric plasma bubbles over Hainan during the super geomagnetic storm in March 2015 are studied using airglow images of 630 nm emission from all-sky imager, digisonde and echo intensity data of Viral Hemorrhagic Fever (VHF) radar over Hainan Fuke Station (19.5°N, 109.1°E) from the Chinese Meridian Project, horizontal magnetic component data from the Dalat geomagnetic station (11.9°N, 108.5°E; GL:2.5°) and PHU Thuy geomagnetic station (21.0°N, 105.9°E; GL:11.5°), and interplanetary magnetic field and solar wind velocity data from the ACE satellite. The results indicate that plasma bubbles before and after magnetic storm are observed during post-sunset hours, along with a uplift of the ionospheric virtual height. During the storm, the uplift of the ionospheric virtual height is significantly suppressed, and no plasma bubbles are detected at the Fuke station. Analysis of the variations in the interplanetary electric/magnetic fields and horizontal geomagnetic components suggests that during the geomagnetic storm, the ionospheric Pre-reversal enhancement electric field is likely suppressed successively by the westward shielding electric field and the disturbance dynamo electric field. This suppression reduced the Rayleigh-Taylor instability, thus inhibiting the development of plasma bubbles/ionospheric irregularity structures.