Five years of lidar ratio measurements over Potenza, Italy

摘要

Lidar technique is the most suitable for high vertical and temporal resolution aerosol profiling. In particular the Raman/elastic lidar combined approach allows independent determination of aerosol extinction and backscatter coefficient without any assumption about their relationship. This technique allows the determination of vertical profiles of the lidar ratio, i.e. the ratio of aerosol extinction and backscatter coefficients. In elastic lidar technique an assumption on the lidar ratio profile is needed for the retrieval of aerosol backscatter coefficient. To improve aerosol backscatter coefficient accuracy in the case of pure elastic backscatter lidar, a climatology of lidar ratio values for specific aerosol types is necessary. Five years of systematic lidar ratio measurements have been collected by means of a Raman/elastic lidar system operational at CNR-IMAA, since May 2000 in the framework of EARLINET, the first lidar network for tropospheric aerosol study on continental scale. The dependence of lidar ratio as a function of the altitude is analysed. A climatological analysis of the lidar ratio measurements in the Planetary Boundary Layer (PBL) and for Saharan dust intrusions is carried out. In addition, lidar ratio measurements concerning forest fires and volcanic eruptions are also analyzed.