A statistical study on the correlation between sporadic Ca⁺ layer and Es in Beijing (40.5°N, 116°E)

From April 2020 to June 2022, a Ca⁺ lidar with dual-wavelength and narrow-band emitting lasers utilizing all-solid-state technology was employed to conduct observations in Beijing (40.41°N, 116.01°E) for a total duration of 1797.79 hours over 280 nights. A total of 286 sporadic Ca⁺ layers were observed, with heights ranging from 88 to 120 km and densities varying from 5.33 to 2200 cm⁻³. We simultaneously observed the ionosonde, located 28 km from the lidar, and found a correlation of 61.89% between the sporadic Ca⁺ layer and the sporadic E layer. When the sporadic Ca⁺ layer has a downward phase trend, there is a correlation of 76.84%. By excluding the influence of ionosonde sensitivity, we focus only on calcium ions that have a density exceeding 140 cm⁻³, which exhibit a correlation of 82.25%. Above 100 km, the correlation significantly increases, reaching approximately 90%. Furthermore, the correlation between the sporadic Ca⁺ layer and the sporadic E layer is particularly noticeable during the summer season, reaching around 90%. This phenomenon can be attributed to the variations in metal ions that occur during different seasons.