激光雷达和探空反演的混合层高度对比分析

本文利用2016年12月至2017年11月期间晴朗少云天气下的成都微脉冲激光雷达观测数据反演的混合层高度,与温江探空资料确定的混合层高度进行了对比和误差分析,结果表明:基于探空资料和激光雷达数据反演的混合层高度具有较好的一致性,两者相关系数达0.75,激光雷达反演的混合层高度略低于基于探空资料确定的值,在混合层高度为1000~2000m时,两种方法计算所得的值偏差幅度最小,约为20%;在1000m以内和2000m以上,偏差幅度略有增大,为26%;两种方法反演的混合层高度变化趋势较为一致,均呈现出12月、1月较低,4月、5月较高的特点;混合层高度具有明显的日变化特征:上午混合层高度迅速增高,午后增长速度减慢并发展到最大高度,日落后迅速降低;混合层内相对湿度的增加、残留层的存在是导致激光雷达反演混合层高度时产生较大误差的原因之一。

Comparison of Mixing Heights Determined by Lidar and Radiosonde Profiles in Chengdu

The mixing heights determined by the micro pulse lidar and radiosonde profile data on sunny days (from December 2016 to November 2017) in Chengdu are compared. The error analysis of mixing heights based on lidar is made. The results show that: The mixing heights determined by micro pulse lidar and radiosonde data have good consistency (the correlation coefficient is 0.75), which indicates that it is accurate to use the micro pulse lidar data to invert the mixing heights in Chengdu. The mixing heights inverted by lidar data are slightly lower than the values determined by radiosonde data. The deviation of the values which are determined by the two methods is very small (about 20%) when the mixing height is from 1000 m to 2000 m. The deviation increases slightly (26%) when the mixing heights are lower than 1000 m or higher than 2000 m. The variation trend of mixing heights determined by the two methods is relatively consistent, which are lower in December and January, and higher in April and May. The mixing heights determined by lidar have obvious diurnal variation characteristics. The mixing heights increase rapidly in the morning and the growth rates slowdown in the afternoon. The mixing heights reach the maximum in the afternoon, and decrease rapidly after sunset. The increase of relative humidity and the existence of the residual layer are the reasons that lead to the large error in the inversion of the mixing layer height based on lidar data.