Biomass burning events measured by lidars in EARLINET. Part I. Data analysis methodology

Abstract

Abstract. The methodology of analysing the biomass burning events recorded in the database of the European Aerosol Research Lidar Network in the frame of Aerosol Cloud and Trace Gases Research Infrastructure is presented. The period of 2008–2017 was chosen to analyse all of the events stored in the database under Forest Fire category for a number of 14 stations available. The data provided ranged from complete data sets (particle backscatter, extinction and linear depolarization ratio profiles) to single profiles (particle backscatter coefficient profile). Smoke layers geometry was evaluated and the mean optical properties within each layer were computed. The backtrajectories technique was used to double check the source of all pollution layers. The biomass burning layers were identified taking into account the presence of the fires along the backtrajectory. The biomass burning events are analysed by the means of the intensive parameters. The analysis was structured in three directions: I) common biomass burning source (fire) recorded by at least two stations, II) long-range transport from N. America, III) analysis over four geographical regions (SE Europe, NE Europe, Central Europe and SW Europe). Based on backtrajectories calculations and fires’ location, the lidar measurements can be labelled either as measurements of ‘single fire’ or ‘mixed fires’ (case I), measurements of N America fires or measurements of mixed N America and local fires (case II). The histogram of the fires’ location reveals the smoke sources for each region. For each region, statistics on intensive parameters is performed. The sources’ origin of the intensive parameters is categorized based on the continental origin of the air-mass (European, African, Asian, N American or a combination of them). The methodology presented here is meant to provide a perspective to explore large amount of lidar data and deliver novel approaches to analyse the intensive parameters based on the assigned biomass burning sources. A thorough consideration of all potential fires’ sources reveals that most of the time the lidar measurements characterise the smoke from a mixture of fires. A comprehensive discussion over all results (based on the intensive parameters and the sources’ location), will be given in a companion paper submitted to ACP EARLINET special issue.