大连地区一次沙尘过程的激光雷达观测研究

Lidar Detection of a Sand-dust Process in Dalian, Liaoning, China

利用激光雷达、PM10观测、地面及探空等综合观测资料,针对大连地区2006年4月7—8日的沙尘过程,基于Fernald积分法反演了沙尘过程气溶胶消光系数,分析了沙尘过程的时空分布特征及沙尘气溶胶的垂直结构,并对沙尘严重影响地面的原因进行了初步探讨。结果表明,激光雷达探测可以精确反映沙尘气溶胶的垂直结构和时空变化信息,并且能弥补人工气象观测的不足;此次沙尘影响高度较低,主体过境时沙尘层中心高度小于0.5km。沙尘层内消光系数最大达到0.96km-1;激光雷达反演得到的180m高度处的气溶胶消光系数与地面PM10浓度吻合较好;沙尘影响地面时,地面PM10浓度增大,相对湿度明显降低。大气低层逆温和近地面风速等气象条件对沙尘影响地面的时间和程度有很大作用。

A sand-dust process in Dalian on Apr 7 and 8, 2006 was monitored based on a Lidar system and conventional meteorological observation instruments, and then the temporal-spatial variation and impact of the sand-dust process was analyzed. The aerosol extinction coefficient was retrieved based on the Fernald integral method, and then the vertical structure of sand-dust aerosol was analyzed. The results indicated that the Lidar system remedied the defects of the conventional meteorological observation instruments, and it could collected the information on the vertical structure of sand-dust aerosol and the temporal-spatial variation of the sand-dust process. The height of the sand-dust center was lower than 0.5 km when the sand-dust event took place in Dalian on Apr 7 and 8, 2006 and the maximal aerosol extinction coefficient reached 0.96 km^-1. There was a strong correlation between the aerosol extinction coefficient at 180 m retrieved from the Lidar data and the concentration of PM10 at land surface. The concentration of PM10 at land surface increased and the relative humidity fell significantly when the sand-dust process sustained. The meteorological conditions such as inversion of lower atmospheric and wind speed near the ground had a great impact on the duration and intensity of the sand-dust event.