Document details

Forest Fire Smoke Layers Observed in the Free Troposphere over Portugal with a ...

Author(s): Preißler, Jana cv logo 1 ; Silva, Ana Maria cv logo 2 ; Wagner, Frank cv logo 3 ; Nepomuceno Pereira, Sérgio cv logo 4 ; Guerrero-Rascado, Juan Luis cv logo 5

Date: 2014

Persistent ID: http://hdl.handle.net/10174/11313

Origin: Repositório Científico da Universidade de Évora

Subject(s): atmospheric aerosols; Raman lidar; forest fires smoke


Description
Vertically resolved optical and microphysical properties of biomass burning aerosols, measured in 2011 with a multiwavelength Raman lidar, are presented.Thetransportation time, within 1-2 days (or less), pointed towards the presence of relatively fresh smoke particles over the site. Some strong layers aloftwere observedwith particle backscatter and extinction coefficients (at 355 nm) greater than 5Mm−1 sr−1 and close to 300Mm−1, respectively. The particle intensive optical properties showed features different from the ones reported for aged smoke, but rather consistent with fresh smoke.The ˚Angstr¨om 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 um, 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.
Document Type Article
Language Portuguese
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