Long-Term Comparison of Lidar Derived Aerosol Optical Depth Between Two Operational Algorithms and Sun Photometer Measurements for Thessaloniki, Greece

Abstract

Results of a multi-year comparison of the aerosol optical depth, derived by two operational algorithms based on lidar measurements with a Raman/elastic backscatter lidar in Thessaloniki, Greece and ground-based sun photometer observations are presented. Measurements from the European Aerosol Research Lidar Network (EARLINET) database processed with the operational algorithm of Aristotle University of Thessaloniki (AUTH) for the period 2001–2007, have been reprocessed with the Single Calculus Chain (SCC) algorithm. The SCC algorithm was developed within the EARLINET to provide high quality, standardized aerosol optical products in near real time. The objective of this study is to verify for the case of Thessaloniki, the long-term consistency of the aerosol load estimates between the operational and the SCC derived data, in order to adopt the SCC for operational processing. The observed differences would introduce inhomogeneities in the time series when switching to SCC, so a full reprocessing is required. An investigation of the parameters affecting the comparisons is presented, considering the differences in the algorithms.