A new method for deriving equatorial plasma bubble velocity by tracing OI 630 nm all-sky images

Abstract

A new method for estimating the equatorial plasma bubbles (EPBs) motions from airglow emission all-sky images is presented in this paper. This method, which is called cloud motion wind (CMW) and widely used in satellite observation of wind, could reasonably derive zonal and meridional velocity vectors of EPBs drift by tracking a series of successive airglow images. Airglow emission images data are available from all-sky airglow camera in Hainan Fuke (19.5°N, 109.2°E) supported by China Meridional Project, which can receive the 630.0 nm emission from ionosphere F region at low latitudes to observe plasma bubbles. A series of pretreatment technology is utilized to preprocess the raw observation. Then the regions of plasma bubble extracted from the images are divided into several small tracing windows, and each tracing window can find a target window in the searching area in following image, which is considered as the position tracing window moved to. According to this, velocity of each tracing window was calculated by CMW. The maximum correlation coefficient is adopted to analyze the velocity of plasma bubbles due to its better performance than histogram of oriented gradient. All-sky images from Hainan Fuke, an example on 17 September 2014, are analyzed to investigate the plasma bubble drift velocities using CMW. For comparison and validation, EPBs motions obtained from three traditional methods are also investigated. The advantages and disadvantages of using CMW are discussed. The results of CMW are compared with slant total electron contents data and show a good consistency, but some errors are also discussed.