Tesche Matthias, Ansmann Albert, Müller Detlef, Althausen Dietrich, Engelmann Ronny, Hu Min, Zhang Yuanghang
Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany.
Appl Opt. 2007 Sep 1;46(25):6302-8. doi: 10.1364/ao.46.006302.
Aerosol Raman lidar observations of profiles of the particle extinction and backscatter coefficients and the respective extinction-to-backscatter ratio (lidar ratio) were performed under highly polluted conditions in the Pearl River Delta (PRD) in southern China in October 2004 and at Beijing during a clear period with moderately polluted to background aerosol conditions in January 2005. The anthropogenic haze in the PRD is characterized by volume light-extinction coefficients of particles ranging from approximately 200 to 800 Mm(-1) and lidar ratios mostly between 40 and 55 sr (average of 47+/-6 sr). Almost clean air masses were observed throughout the measurements of the Beijing campaign. These air masses originated from arid desert-steppe-like regions (greater Gobi area). Extinction values usually varied between 100 and 300 Mm(-1), and the lidar ratios were considerably lower (compared with PRD values) with values mostly from 30 to 45 sr (average of 38+/-7 sr). Gobi dust partly influenced the observations. Unexpectedly low lidar ratios of approximately 25 sr were found for a case of background aerosol with a low optical depth of 0.05. The low lidar ratios are consistent with Mie-scattering calculations applied to ground-based observations of particle size distributions.
2004年10月在中国南方珠江三角洲（PRD）高度污染条件下以及2005年1月在北京清洁时段且气溶胶条件为中度污染至背景水平时，利用气溶胶拉曼激光雷达对颗粒物消光系数、后向散射系数以及各自的消光与后向散射比（激光雷达比）的垂直分布进行了观测。珠江三角洲的人为霾特征表现为颗粒物的体积消光系数约为200至800Mm⁻¹，激光雷达比大多在40至55sr之间（平均为47±6sr）。在北京观测期间，整个测量过程中几乎都观测到了清洁气团。这些气团源自干旱的类似沙漠草原的地区（大戈壁地区）。消光值通常在100至300Mm⁻¹之间变化，并且激光雷达比（与珠江三角洲的值相比）要低得多，大多在30至45sr之间（平均为38±7sr）。戈壁沙尘对观测有一定影响。对于一个光学厚度低至0.05的背景气溶胶情况，发现了意外低的约25sr的激光雷达比。这些低激光雷达比与应用于地面观测的颗粒物粒径分布的米氏散射计算结果一致。
