Characterization of fresh and aged biomass burning events using multiwavelength Raman lidar and mass spectrometry

• Published in: Journal of geophysical research. Atmospheres Vol. 118; no. 7; pp. 2956 - 2965
• Main Authors: Nicolae, D., Nemuc, A., Müller, D., Talianu, C., Vasilescu, J., Belegante, L., Kolgotin, A.
• Format: Journal Article
• Language: English
• Published: Hoboken, NJ Blackwell Publishing Ltd 16-04-2013; John Wiley & Sons
• Subjects: aerosol mass spectrometry; aerosol microphysical properties; Aerosols; Aircraft components; Albedo; AMS; Atmospheric evolution; Biomass; Biomass burning; biomass burning aerosols; Chemical analysis; Exponents; Geophysics; Lidar; Mass spectrometry; Refractive index; Refractivity; Smoke
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/jgrd.50324

This paper focuses on optical and microphysical properties of long‐range transported biomass burning (BB) aerosols and their variation with atmospheric evolution (ageing), as observed by a multiwavelength Raman lidar, part of EARLINET (European Aerosol LIdar NETwork). Chemical analysis of the atmospheric aerosol was done using a colocated aerosol mass spectrometer (AMS). One relevant optical parameter for the ageing process is the Ångström exponent. In our study, we find that it decreases from 2 for fresh to 1.4–0.5 for aged smoke particles. The ratio of lidar (extinction‐to‐backscatter) ratios (LR532/LR355) changes rapidly from values <1 for fresh to >1 for aged particles. The imaginary part of the refractive index is the most sensitive microphysical parameter. It decreases sharply from 0.05 to less than 0.01 for fresh and aged smoke particles, respectively. Single‐scattering albedo (SSA) varies from 0.74 to 0.98 depending on aerosol age and source. The AMS was used to measure the marker ions of wood‐burning particles during 2 days of measurements when the meteorological conditions favored the downward mixing of aerosols from lofted layers. Particle size distribution and particle effective radius from both AMS and lidar are similar, i.e., particle effective radii were approximately 0.27 µm for fresh BB aerosol particles. Microphysical aerosol properties from inversion of the lidar data agree with similar studies carried out in different regions on the globe. Our study shows that the Ångström exponent LR532/LR355 and the imaginary part of the refractive index can be used to clearly distinguish between fresh and aged smoke particles.
Key Points
variation of microphysical properties of biomass burning aerosol from lidarAngstrom exponent, LR532/LR355, imaginary part‐ refractive index good indicatorscharacteristics of biomass burning aerosols from lidar and mass spectrometry