Meteoric Ca Ion Transport From ∼80 to 300 km in the Midlatitude Nighttime Ionosphere

We report a world record of lidar profiling of metallic Ca⁺ ions up to 300 km in the midlatitude nighttime ionosphere during geomagnetic quiet time. Ca⁺ measurements (∼80–300 km) were made over Beijing (40.42°N, 116.02°E) with an Optical-Parametric-Oscillator-based lidar from March 2020 through June 2021. Main Ca⁺ layers (80–100 km) persist through all nights, and high-density sporadic Ca⁺ layers (∼100–120 km) frequently occur in summer. Thermosphere-ionosphere Ca⁺ (TICa⁺) layers (∼110–300 km) are likely formed via Ca⁺ uplifting from these sporadic layers. The lidar observations capture the complete evolution of TICa⁺ layers from onset to ending, revealing intriguing features. Concurrent ionosonde measurements show strong sporadic E layers developed before TICa⁺ and spread F onset. Neutral winds can partially account for observed vertical transport but enhanced electric fields are required to explain the results. Such lidar observations promise new insights into E- and F-region coupling and plasma inhomogeneities.