First Observation of Ionospheric Plasma Bubble Signatures by Ca+ Lidar at Low Latitude

Abstract Ionospheric plasma bubbles refer to density depletion structures in the ionosphere, which are usually seen in the electron density profiles observed by radar, and have never been observed in the density profiles of metallic ions. In this letter, we report the first observation of plasma bubble signatures captured by lidar, manifested as depletion and bifurcation structures in the density profile of a Ca + patch appearing at F‐region height over low latitude. Different from majority of plasma bubbles observed by radar mainly seen in F‐region altitude, the bubble depletion signatures visualized by lidar at low latitude could be down to below the F layer bottom, that is, valley‐region altitude ∼150 km. The results highlight the possibility of plasma bubbles to create depletion structures in metallic ion profiles appearing at F region, and provide a new method to investigate plasma bubbles by lidar.