Measurements of aerosol extinction-to-backscatter ratio and its variation at Beijing

ABSTRACT The extinction-to-backscatter ratio, S1, is a crucial parameter for quantitative interpretation of lidar data. A new methodwill be presented for obtaining aerosol extinction-backscatter-ratio S in the aerosol layer near the ground by using OPC,visibility-meter and particle-monitors. According to the measured data in Beijing during two periods of August of 2001and January of 2002, the variation of S will be discussed. 1. INTRODUCTION Aerosol, dust, and pollutant gases produced by nature and human activities are trapped within the atmospheric boundarylayer (ABL) near the ground. The ABL is generally regarded as an important link between the earth's surface and thefree atmosphere. The ABL plays an important role in atmospheric circulation. The knowledge of aerosol verticalprofiles and their time variation in the layer is needed to fully understand this link. The aerosols have also importantimpact on human living condition. The knowledge of the aerosol vertical structure in the layer is important also forprediction and further improving air-quality, especially at the urban area. In order to monitor the variation of aerosol