中文摘要：

利用双波长激光雷达观测合肥地区地表气溶胶的波长指数,根据观测期间的风向信息,选择了城市污染和乡村扬尘气溶胶作为两次典型个例,分析相对湿度（RH）对气溶胶波长指数（AE）变化规律的影响。观测结果表明,两次个例相对湿度对波长指数的影响均较明显,但是两次个例中波长指数与相对湿度之间的相关性明显不同。扬尘个例期间,当相对湿度在49.2%～91.9%之间变化时,波长指数的变化范围为0.75～1.98。污染个例期间,当相对湿度在58.7%～96.0%之间变化时,波长指数的变化范围为0.2～1.56。污染个例期间,相对湿度与波长指数之间呈负相关性,导致该现象的原因可能是,当粒子尺度谱满足Junge分布时,由于亲水型粒子吸湿增长,导致其粒径增大以及波长指数减小。值得注意的是,扬尘个例期间,相对湿度与波长指数之间却呈正相关性,导致该现象的原因可能是粒子尺度谱分布是由污染细粒子和扬尘粗粒子组成的多模态分布。

英文摘要：

In order to determine the relative humidity（RH） impact on the aerosol ？ngstr？m exponent（AE）, a twowavelength lidar is employed to observe the aerosol AE, two typical case studies have been given at Hefei area based on the wind direction, one represents pollution aerosol case, and the other represents rural aerosol case. The result indicates that during the two cases the RH has a strong effect on the variety of the AE, but totally different correlation between the two parameters can be found. During the rural case, the RH is between 49.2%～91.9%, the AE is between 0.75～1.98, and the AE of the pollution case is between 0.2～1.56 when the RH changed between58.7%～96.0%. The pollution case presents a negative correlation between the RH and the AE, due to the aerosol hydrophilic growth with a Junge distribution. It is noteworthy that the rural case presents a positive correlation between the RH and the AE, the cause of this phenomenon is probably that particle size distribution is multimodal distribution composed of fine particles and coarse particles of dust pollution.