Aerosol size distribution measurements using a multispectral lidar system
Authors: Kolenda Juergen, Mielke Bernd, Rairoux Patrick, Stein Bernhard, Weidauer D., Wolf Jean-Pierre, Woeste Ludger H., Castagnoli F., Del Guasta M., Morandi M., Sacco V.M., Stefanutti Leopoldo, Venturi V., Zuccagnoli L.
Autors Affiliation: Freie Univ. Berlin, Berlin, Ger
Abstract: A new inversion algorithm has been developed to determine the aerosol size distribution from LIDAR signals obtained at several wavelengths. This algorithm is based on a non-linear fit of the backscattered measurements using a set of predetermined functions. Two function types have been taken into account to describe the size distribution of tropospheric aerosols: Junge distribution for clear atmosphere and log normal distribution for fogs and clouds. This method has been tested using a four-wavelength lidar system (300 nm, 600 nm, 695 nm, 760 nm). Lidar measurements made in Central Switzerland (Rigi), characterized by a specific micro- climate, allowed us to determine size distribution profiles of tropospheric aerosols in different meteorological conditions: clear, hazy, and cloudy atmosphere. The distribution parameters (concentration, mean radius, standard deviation) have since been obtained. Stratospheric clouds and aerosols, created by the Pinatubo eruption, have been measured above Berlin, Germany and Sodankyla, Finland with a lidar at five wavelengths: 355 nm, 532 nm (Nd:YAG), 750 nm, 800 nm, and 850 nm (flashlamp-pumped Ti:Sapphire). These measurements were used to characterize the size distribution of these volcanic aerosols in order to estimate their influence on radiative transfers. Depolarization measurements were performed to distinguish between different types of aerosols.
KeyWords: Aerosols; Algorithms, Backscattered measurements; Depolarization; Junge distribution; Multispectral lidat system, Optical radarDOI: 10.1117/12.138527