Por: Jana Preissler

Data: 23 de Maio

Hora: 14:30
Local: Anfiteatro 1 - CLAV

Abstract:

Ground based lidar systems enable the temporally and vertically resolved detection of atmospheric aerosols. Laser light emitted by the instrument is scattered on particles. The backscattered photons are then detected by the lidar. Thus, optical properties of atmospheric particles can be obtained, like particle extinction and backscatter coefficients, particle depolarisation, Ångström exponents and aerosol optical depths. However, in case of ground based lidar measurements the vertically resolved data is only available at one point. For this study, lidar data from two EARLINET (European Aerosol Research Lidar Network) stations located in the southern part of the Iberian Peninsula (Granada, Spain and Évora, Portugal) were combined. Furthermore, sun-photometer and satellite data were used in order to study the vertical and horizontal distribution of aerosol plumes and to characterise the aerosols. The distance between the two stations is about 410 km. The ground-based lidar systems in Granada and Évora both enable the determination of the particle extinction coefficients at 355 and 532 nm, the particle backscatter coefficients at 355, 532 and 1064 nm as well as the depolarisation ratio at 532 nm. Considered were aerosol layers above the boundary layer, which were observed by both lidar stations. Three cases of free tropospheric aerosol layers have been studied: Forest fire smoke from North America observed between about 5 and 7 km asl on 13 June 2011; Saharan dust between 2 and 5 km asl in the night from 26 to 27 June 2011; and another layer of Saharan dust detected between 3 and 4 km asl on 29 August 2011. For all three cases profiles of the extinction and backscatter coefficients as well as lidar ratios, Ångström exponents and the linear particle depolarisation ratio from ground-based lidar measurements in Granada and Évora will be presented and compared.