Optical observation of plasma bubbles and comparative study of multiple methods of observing the ionosphere over China.

• The all-sky airglow imager and Digisonde data were used to investigate plasma bubbles. • Optical image processing was performed to obtain image products with high resolution. • Plasma bubbles appeared like long stripe and bifurcated vertically. • The distance between adjacent plasma bubbles was in the range of 100–400 km. • Plasma bubbles generally drifted eastward and the average drift velocity was 90 m/s. Ionospheric plasma bubbles and scintillation phenomena often occur at low latitudes in China. The all-sky airglow imager located at Fuke station in Hainan (19.5°N, 109.2°E) is part of the Meridian project in China. In this work, we used mainly the observation data obtained by the imager and a digisonde to study plasma bubbles. Optical image processing—including image enhancement, azimuth correction and image projection—was performed on the original airglow observation images, and clear high-resolution images of the bubbles were obtained. Based on these, the morphological features, spatial and temporal variations, spatial scale, drift velocity of the plasma bubbles in the F region of the ionosphere were investigated and analyzed. The plasma bubbles appeared as long, dark stripes on the bright airglow emission background. Their large-scale structures often bifurcated vertically, and were usually tilted westward with north-south extension along the magnetic field lines. The east-west scale of the plasma bubbles was usually greater than 200 km and these increased gradually with time. Moreover, the distance between the adjacent plasma bubbles also increased over time, and was in the 100–400 km range. Plasma bubbles generally drifted eastward with an average drift velocity of approximately 90 m/s. The occurrence and duration of the plasma bubbles were compared with digisonde observations, and it was shown that plasma bubbles lasted for nearly four hours. Additionally, the main characteristics of the plasma bubbles were obtained using both optical and radio observations and the study of which can be beneficial for monitoring and predicting ionospheric scintillations. [ABSTRACT FROM AUTHOR]