Observation of middle and upper atmospheric stability over Hainan, China based on sodium lidar

Sodium lidar, with its excellent temporal and spatial resolution, can accurately detect dynamic and chemical change information in the mesopause region, which is commonly considered to be an important tool for studying gravity wave (GW) disturbances and changes in the middle and upper atmosphere. In this study, based on Meridian Project nighttime sodium lidar data collected from 2010 to 2013 at the Haikou station (19.99°N, 110.34°E), a deep analysis of the seasonal distribution of stability parameters in the middle and upper atmosphere at Hainan low latitudes was reported. The result shows that Richardson numbers are mainly distributed between 0.75 and 2 for most of the year, with an average value of approximately 1.49. Compared to spring and autumn, atmospheric disturbances are more intense in summer and winter in Hainan. And by analyzing the seasonal distribution of horizontal wind disturbances and evolution of the sodium layer within single day, the unstable processes during disturbance events was explored in this paper. Additionally, it was found that some special events in autumn, lead the notable atmospheric disturbances during this season. The still active GW activities in winter may be the main reason for the unstable processes in the middle and upper atmosphere from November to December. Analysis of ionospheric data indicated correlation between atmospheric instability and the sporadic E-layer observed by nearby ground-based stations are weak, while GWs and other disturbances formed by Earth′s terrain and activities have a more significant impact on the shape and stability of the sodium layer. These above results can help us better understand the dynamic mechanisms of the middle and upper atmosphere at low latitudes and the global mid-to-low latitude atmospheric circulation processes.