半干旱地区卷云特征的激光雷达探测

Cirrus Cloud Measurement Using Lidar over Semi-Arid Areas

利用兰州大学半干旱气候与环境观测站（SACOL）2007年4~11月微脉冲激光雷达（MPL-4B）观测资料,统计分析了卷云的高度、厚度及其变化特征。采用透过率方法计算了卷云光学厚度,得到了卷云光学厚度与卷云厚度和云底高度的相关关系。结果表明,SACOL卷云出现的平均海拔高度为10.16±1.32 km;卷云厚度分布范围为0.30~2.80 km,平均值为1.10±0.49 km;光学厚度分布范围为0.003~1.057,平均值为0.17±0.16,SACOL卷云以光学厚度小于0.3的薄卷云为主;6、7、8月卷云出现高度较其他月大,厚度和光学厚度较小;卷云光学厚度与卷云厚度呈正的线性相关关系。

By using cirrus measurements with a Micro Pulse Lidar（MPL-4B） at the Semi-Arid Climate and Environment Observatory of Lanzhou University（SACOL） from April to November in 2007,the statistical analysis is made for both cirrus height and thickness.The optical depth of cirrus is derived through transmittance method,and the relationship of the cirrus optical depth depending on the cirrus thickness and cloud base height is got.The results show that the mean value of the cirrus height at the SACOL is 10.16±1.32 km above sea level.The cirrus thickness varies between 0.3 and 2.8 km,and the mean value is 1.10±0.49 km.The cirrus optical depth varies between 0.003 and 1.057,and the mean value is 0.17±0.16.Most cirrus observed at the SACOL is thin cirrus whose optical depth is less than 0.3.From June to August,the cirrus height is higher and the optical depth and thickness are less than those in other months.The results show that the cirrus optical depth and thickness follow a positive linear relation.