中文摘要：

利用延庆瑞利激光雷达（40.47°N,115.97°E）2012年1-2月及2012年5月至2013年4月的探测数据,分析得到北京上空60~80 km高度140个晚间的温度廓线,对这一区域内的低中间层逆温层现象（Lower Mesospheric Inversion Layer,Lower MIL）进行了统计分析,发现平均逆温幅度为23.4 K,平均垂直尺度为4.78 km,逆温层底部平均高度为68.2 km.约有2/3的逆温层存在随时间垂直传播现象,且大多为向下传播.此外,还观测到三个垂直传播速度相差近一倍的特殊双低层MIL演化现象.

英文摘要：

By using the measurement data of Rayleigh Lidar located in Yanqing, Beijing （40.47~N, 115.97~E） during the period from January to February 2012 and from May 2012 to April 2013, statistic characteristics of lower Mesosphere Inversion Layers （MIL） occurring between 60 and 80 km altitude over North China have been reported. The occurrence of lower MIL in Beijing was found to be 65% in this period. The mean bottom/top height was 68.2 km （73.0 km） and mean thickness was 4.8 kin. 47 inversion events propagated downward while 12 inversion events propagated upward in 91 lower MIL events. Notably, 3 double lower MIL events vertically propagated in quite different speed and direction. During the double lower MIL on 17 May 2012, the upper MIL and the lower MIL propagated downward with vertical speed of 610 m.h-1 and 460 m.h-1 respectively. And during the double lower MIL observed on 8 February 2013, the upper spread propagated upward while the lower spread propagated downward with vertical speed of 512 m·h-1 and 263 m·h-1 respectively. However, during the double lower-MIL on 18 February 2013, the lower MIL was spreading downward with a speed of 1300 m·h-1 with inversion amplitude increasing. After the amplitude reached its maximum value, a weak shallow upper-MIL was split out from the MIL. All these are analyzed in detail.