Seasonal Variation in the Mesospheric Ca Layer and Ca⁺ Layer Simultaneously Observed over Beijing (40.41N, 116.01E)

In March 2020, an all-solid-state dual-wavelength narrow-band lidar system was deployed. A total of 226 nights spanning from March 2020 to July 2022 were employed in order to investigate the seasonal variations of calcium atoms and ions in the mesosphere over Beijing (40.41 degrees N, 116.01 degrees E). The Ca+ layer shows general annual variation, while a semiannual variation is observed on the Ca layer. The calcium atomic column densities ranged from 2.0 x 10(6) to 1.1 x 10(8) cm(-2), and the calcium ion column densities ranged from 1.6 x 10(6) to 4.2 x 10(8) cm(-2). The mean centroid heights of Ca+ and Ca are 98.6 km and 93.0 km, respectively, and the centroid heights of Ca+ and Ca are mostly influenced by annual variations. The seasonal variation in the Ca+ and Ca layers in Beijing exhibits similarities to that of K & uuml;hlungsborn (54 degrees N). While the peak density of Ca+ in Beijing are similar to those observed in K & uuml;hlungsborn, the peak density of the Ca layer in Beijing is about half of that reported in the Ca layer at 54 degrees N. We provide an explanation for the disparities in the column abundance and centroid altitude of the Ca layer between Yanqing and K & uuml;hlungsborn, discussing variations in neutralization among different metal ions.