E. Landulfo¹, A. Papayannis², P. Artaxo³, A. Zanardi de Freitas¹, N.D. Vieria Junior¹, G. Chourdakis², G. Tsaknakis² and M. P. Jorge⁴

¹Instituto de Pesquisas Energéticas e Nucleares, Centro de Lasers e Aplicações Avenida Lineu Prestes, 2242, Cidade Universitária, CEP 05508-900, São Paulo, SP, Brazil.
²National Technical University of Athens, Physics Department, Heroon Polytechniou 9, 15780 Zografou, Greece.
³Institut of Physics, University of S. Paulo, Brazil.
⁴Laboratório Associado de Meteorologia e Oceanografia, Centro de Previsão do Tempo e Estudos Climáticos, Instituto Nacional de Pesquisas Espaciais, Av. dos Astronautas, 1758 ,12201-970, Sao José dos Campos, SP, Brazil.

Every year enhanced concentrations of aerosol species result from biomass burning over the tropical (Amazon) and the Mediterranean forest regions, during the dry season (July – September). In the case of the tropical forest fires, the spatial scales of air pollution correspond to very large areas, of the order of several 106 km2, while they are limited to a few 104 km2 in the case of the Mediterranean forest fires. During the dry season, large-scale atmospheric subsidence over the Amazon typically traps surface gas and aerosol emissions in the lower troposphere, with lateral advection dominating vertical transport processes. Similar effects occurred during the forest fires probed in the Mediterranean region and presented in this study. In this paper we examine some typical biomass burning aerosol loads observed by the lidar technique. These biomass burning aerosols have been advected in the lower troposphere, from their source region to our observing site situated in a distance of about 3000 km (S. Paulo) and of only 15-100 km in the case of Athens. The lidar technique used is based on a single-wavelength backscattering lidar system, operating at 532 nm.

This comparative study considers the aerosol backscattering volume coefficient (baer) retrieved by using the Klett backward inversion technique, as well as the synergetic use of satellite data (TOMS aerosol index) and air mass backward trajectory analysis (only for the S. Paulo site). The comparison between the vertical profiles of baer between S. Paulo and Athens showed that: i) the pyrogenic aerosol loads are observed in the altitude range between 2-5 km height asl.(S. Paulo) and between 2-3.5 km asl. (Athens), ii) the aerosol backscattering volume coefficient (baer) measured over S. Paulo was of the order of 0.001 km-1sr-1, while over Athens reached a value of about 0.09 km-1sr-1. This large difference is explained due to the large dilution effects on the forest fire plume, when travelling from the Amazon to S. Paulo.