一次严重灰霾过程的气溶胶光学特性垂直分布

利用激光雷达在广州地区一次严重灰霾过程进行探测,并反演气溶胶消光系数及退偏比,分析边界层结构演变对气溶胶消光系数廓线分布的影响.结果表明,气溶胶主要在1.5km以下.发生灰霾天气时,霾层达到1km,午后可达1.5km,发生严重灰霾天气时,霾层只有500m.气溶胶消光系数随高度分布在清洁过程中呈线性递减,标高为1490m,在灰霾过程中呈指数递减,标高为789.5m.从气溶胶消光系数廓线变化可以很好地反演边界层结构的演变.气溶胶消光系数在残留层顶出现极大值.气溶胶退偏比有明显的日变化,白天的退偏比比夜间的高,午后出现峰值.该次过程气溶胶的退偏比小于0.2.本地气溶胶廓线只有在清洁过程时与Elterman廓线接近.

The vertical distribution of aerosol optical properties in a severe haze event

This study uses lidar data to investigate a severe haze event in the Guangzhou area. We analyze the impact of the boundary layer structure evolution on the distribution of aerosol extinction coefficient profile, based on the aerosol extinction coefficient and depolarization ratio retrievals. Results show that aerosol particles mainly concentrate below 1.5km in this event. The haze layer mostly extends to 1km and up to 1.5km in the afternoon under moderate haze condition, but only up to 500m under severe haze condition. During clean days, the aerosol extinction coefficient decreases linearly with height, and the scale height at the altitude of 1490m. In contrast, it decreases exponentially and the scale height maximizes at the altitude of 789.5m during haze days. The evolution of boundary layer is well represented by the change of aerosol extinction coefficient profile. The aerosol extinction coefficient peaks at the top of the residual layer. The aerosol depolarization ratio exhibits strong diurnal variation with higher value during daytime than at night and maximum value in the afternoon. In this event, the aerosol depolarization ratio is mostly less than 0.2. Only the clean days display local aerosol profile that is close to the Elterman profile.