北京延庆钠层上边界的平均特性研究

本文对北京延庆(116.0°E，40.5°N)钠荧光激光雷达2018年11月—2019年12月夜间的数据以1 h和1 km的时空分辨率进行了分析.获得了当地钠层上边界可达到的高度范围、其相应的季节变化、夜间演化等：延庆顶部钠层可达到110 km、120 km和130 km的概率分别为99.94%、84.46%和40.34%，由此得出，顶部钠层在大多数情况下可以达到120 km，突破了顶部钠层在105 km(或者110 km)的传统观点；上边界高度范围的季节变化规律为5—6月份最高，2—3月份最低；后半夜顶部钠层密度会有所增加.我们比较了偶发钠层、温度和流星注入与上边界高度范围的相关性，推测出偶发钠层对钠层上边界拓展有很大贡献，流星注入次之，温度影响最低.后半夜流星注入量增多跟此时顶部钠层密度增加有一定的相关性.对顶部钠层能够提高到120 km的这项研究，可以为拓展风温的探测高度提供理论依据.

Study on average characteristics of upper boundary of sodium layer in Yanqing,Beijing

In this paper, data from the sodium fluorescence lidar of Yanqing, Beijing (116.0°E, 40.5°N) for the night of November 2018-December 2019 were analysed at resolution of 1 km and 1 hour. The range of heights that can be reached at the upper boundary of the sodium layer, its corresponding seasonal variability, and nighttime evolution were obtained: the probabilities that the top sodium layer in Yanqing can reach 110 km, 120 km and 130 km are 99.94%, 84.46% and 40.34%, respectively, leading to the conclusion that the top sodium layer can reach 120 km in most cases, breaking the traditional view that the top sodium layer is at 105 km (or 110 km); the seasonal pattern of the upper boundary is highest in May-June and lowest in February-March; the density of the top sodium layer increases during the second half of the night. We compare the correlations of sporadic sodium layer, temperature and meteor injection with the upper boundary altitude range and conclude that sporadic sodium layer contributes significantly to the expansion of the upper boundary of the sodium layer, followed by temperature and meteor injection. Moreover, the increased meteor injection in the latter half of the night correlates with the increased density of the top sodium layer at this time. The study of the ability to increase the top sodium layer to 120 km may provide a theoretical basis for extending the detection height of the wind temperature.