中文摘要：

2011年3～4月，利用车载多普勒测风激光雷达系统在北京观象台（39°48’N，116°28’E）进行观测期间，在天气晴朗、无明显云的4月12日晚8时成功捕获到对流层顶附近薄卷云的存在。对激光雷达信号进行背景噪声剔除、平滑滤波和距离平方校正等处理后，时间一高度显示结果表明，该卷云位于约11km高度，厚约250m。利用Fernald方法反演激光雷达不同时刻和不同方向的观测信号，所获得大气消光系数剖面显示出该卷云存在明显时空变化，与探空资料对比显示其位于对流层顶。最后，通过对大气消光系数积分得到该层卷云光学厚度为0．02，透过率为98．02％，这与经常在南北纬30°间出现的对流层顶薄卷云（不可见卷云）具有相似性。

英文摘要：

When the mobile Doppler wind lidar was operated in Beijing observatory （39°48, N, 116°28＇ E） from March to April in 2011 ,a thin cirrus was captured successfully at 8 = 00 pm,April 12 ,with free of obvious cloud. The lidar signals are processed by reducing background noise, smoothing and range fsquare correcting. The time-height indication of lidar signals shows that the cirrus is about 11 km high and 250 m thick. The spatial and temporal changes of cirrus are analyzed through the extinction coefficients in different moments and directions. Compared with the radiosonde temperature, the cirrus is near the trop opause. Its optical depth is about 0.02 by integrating the extinction coefficient and the transmittance is a- bout 98.02% ,which are similar to those of the tropopause cirrus （sub-visual cirrus） between northern and southern 30° of latitude.