基于微脉冲激光雷达观测资料的半干旱区沙尘天气消光效应分析

Analysis of Aerosol Extinction Coefficient Under Different Weather Condition Based on MPL Monitoring Data in the Semi-arid Region in Northwest China

利用兰州大学半干旱区气候与环境观测站（SOCAL）的微脉冲激光雷达（MPL）2008年4月30日至5月2日观测资料，对晴朗天气、浮沉天气及扬沙天气过程中气溶胶垂直分布的连续变化、物理机制进行了对比分析与探讨。结果表明MPL很好地反映出不同天气过程中大气气溶胶廓线的日变化特征：受人类活动影响，天气晴朗时，早晨9时开始在0—2km范围出现气溶胶聚集区，持续至15时，气溶胶平均消光系数〈0．20km-1；受沙尘输送影响，浮尘天气时，气溶胶聚集区高度范围为1—2km，高层气溶胶富集区高度范围为5—7km，气溶胶平均消光系数0．38km-1；扬沙天气时，气溶胶聚集区高度范围为0—1km，浓度远大于浮尘天气，但高层气溶胶浓度较小且分布较均匀，气溶胶平均消光系数〉0．50km-1。

Based on the daily observational data of the micro pulse laser radar （MPL） from April 30 to May 2 in the Semi - Arid Cli- mate and Environment Observatory of Lanzhou University（ SACOL）, the returned signals were measured and the aerosol extinction coef- ficient was calculated to analyze the variation of vertical distribution of aerosol extinction coefficient under different weather conditions. The results show when sky was clear, the aerosol accumulation area appeared in the range of 0 -2 km from 09：00 to 15：00 due to the influence of human activity, and the mean value of aerosol extinction coefficient was less than 0.20 km-~. Under the floating dust weather condition, the aerosol concentrated in lower level ranged from 1 to 2 km and higher level ranged from 5 to 7 km, which influ- enced by sand transport, and the mean value of aerosol extinction coefficient was 0.38 kin-1. Under the blowing sand weather condi- tion, the aerosol concentrated in the level of 0 - 1 km, and the aerosol concentration was so much higher than that under the floating dust weather condition, and in higher level, the aerosol distributed less and evenly, the mean value of aerosol extinction coefficient was more than 0.50 km-1.