title: Forest fire smoke layers observed in the free troposphere over Portugal with a multiwavelength Raman lidar: optical and microphysical properties.
abstract: Vertically resolved optical and microphysical properties of biomass burning aerosols, measured in 2011 with a multiwavelength Raman lidar, are presented. The transportation time, within 1-2 days (or less), pointed towards the presence of relatively fresh smoke particles over the site. Some strong layers aloft were observed with particle backscatter and extinction coefficients (at 355 nm) greater than 5 Mm(-1)sr(-1) and close to 300 Mm(-1), respectively. The particle intensive optical properties showed features different from the ones reported for aged smoke, but rather consistent with fresh smoke. The Ångström exponents were generally high, mainly above 1.4, indicating a dominating accumulation mode. Weak depolarization values, as shown by the small depolarization ratio of 5% or lower, were measured. Furthermore, the lidar ratio presented no clear wavelength dependency. The inversion of the lidar signals provided a set of microphysical properties including particle effective radius below 0.2 μm, which is less than values previously observed for aged smoke particles. Real and imaginary parts of refractive index of about 1.5-1.6 and 0.02i, respectively, were derived. The single scattering albedo was in the range between 0.85 and 0.93; these last two quantities indicate the nonnegligible absorbing characteristics of the observed particles.
authors.affiliation: Évora Geophysics Center, Rua Romão Ramalho 59, 7000 Évora, Portugal ; Andalusian Institute for Earth System Research IISTA-CEAMA, University of Granada, Autonomous Government of Andalusia, Avenida del Mediterráneo s/n, 18006 Granada, Spain.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Nepomuceno Pereira
authors.affiliation: Évora Geophysics Center, Rua Romão Ramalho 59, 7000 Évora, Portugal ; Centre for Climate and Air Pollution Studies (C-CAPS), National University of Ireland Galway, University Road, Galway, Ireland.
authors.forename: Jana
authors.identifier: 0000-0002-8636-5646
authors.initials: J
authors.lastname: Preißler
authors.affiliation: Évora Geophysics Center, Rua Romão Ramalho 59, 7000 Évora, Portugal ; Andalusian Institute for Earth System Research IISTA-CEAMA, University of Granada, Autonomous Government of Andalusia, Avenida del Mediterráneo s/n, 18006 Granada, Spain ; Department of Applied Physics, University of Granada, Fuentenueva s/n, 18071 Granada, Spain.
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: Guerrero-Rascado
authors.affiliation: Évora Geophysics Center, Rua Romão Ramalho 59, 7000 Évora, Portugal.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Silva
authors.affiliation: Évora Geophysics Center, Rua Romão Ramalho 59, 7000 Évora, Portugal ; Deutscher Wetterdienst, Meteorologisches Observatorium Hohenpeißenberg, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Wagner
mesh_terms: D004784:Environmental Monitoring; D005390:Fires; D065928:Forests; D006801:Humans; D011174:Portugal; D012906:Smoke
chemical_list: D012906:Smoke