Lidar Observations of Thermosphere-Ionospheric Ca+ at Mohe (122.3°E, 53.5°N)

The ionosphere is an open area, affected by solar activity or geomagnetic activity, and affected by the lower atmosphere. Moreover, previous studies believed that metallic iron ions were a necessary condition for the formation of ionospheric irregularities, but so far there are no favorable observations to support it. In this paper, we use a Ca⁺ lidar at Mohe to explore the relationship between metal ions and ionospheric irregularities. The reason for choosing Mohe Station is that this region is at the northernmost point of China and is on the edge of the sub-aurora zone during the peak year of solar activity. Mohe thermosphere and ionosphere Ca⁺ (TICa⁺) is associated with Spread F or may be related with magnetic storms. The TICa⁺ generally occurred before dawn. In addition, the density of main Ca⁺ layer (80–120 km) in the autumn months is low, and the upper TICa⁺ (120–300 km) event density is also low with an order of 10 cm⁻³. However, during magnetic storm periods, the density of TICa⁺ increased with an order of 100 cm⁻³, which is comparable to or higher than summer results.