Estimation of the microphysical aerosol properties over Thessaloniki, Greece, during the SCOUT-O3 campaign with the synergy of Raman lidar and Sun photometer data

An experimental campaign was held at Thessaloniki, Greece (40.6 degrees N, 22.9 degrees E), in July 2006, in the framework of the integrated project Stratosphere-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere (SCOUT-O-3). One of the main objectives of the campaign was to determine the local aerosol properties and their impact on the UV irradiance at the Earth's surface. In this article, we present vertically resolved microphysical aerosol properties retrieved from the inversion of optical data that were obtained from a combined one-wavelength Raman/two-wavelength backscatter lidar system and a CIMEL Sun photometer. A number of assumptions were undertaken to overcome the limitations of the existing optical input data needed for the retrieval of microphysical properties. We found acceptable agreement with Aerosol Robotic Network retrievals for the fine-mode particle effective radius, which ranged between 0.11 and 0.19 for the campaign period. It is shown that under complex layering of the aerosols, general assumptions may result in unrealistic retrievals, especially in the presence of aged smoke aerosols. Furthermore, with this instrument setup, the inversion algorithm can also be applied successfully for the complex refractive index in cases of vertically homogeneous layers of continental polluted aerosols. For these inversion cases, the vertically resolved retrievals for the single-scattering albedo resulted in values around 0.9 at 532 nm, which were in very good agreement with estimates from airborne in situ observations obtained in the vicinity of the lidar site.