Abstract
Abstract. The multi-wavelength lidar technique was applied to the study of a smoke event near Washington, DC on 26–28 August 2013. Satellite observations combined with transport model predictions imply that the smoke plume originated mainly from Wyoming/Idaho forest fires and its transportation to Washington, DC took approximately 5 days. The NASA Goddard Space Flight Center (GSFC) multi-wavelength Mie–Raman lidar was used to measure the smoke particle intensive parameters such as extinction and backscatter Ångström exponents together with lidar ratios at 355 and 532 nm wavelengths. For interpretation of the observed vertical profiles of the backscatter Ångström exponents γβ at 355–532 and 532–1064 nm, numerical simulation was performed. The results indicate that, for fine-mode dominant aerosols, the Ångström exponents γβ(355–532) and γβ(532–1064) have essentially different dependence on the particle size and refractive index. Inversion of 3 β + 2 α lidar observations on 27–28 August provided vertical variation of the particle volume, effective radius and the real part of the refractive index through the planetary boundary layer (PBL) and the smoke layer. The particle effective radius decreased with height from approximately 0.27 μm inside the PBL to 0.15 μm in the smoke layer, which was situated above the PBL. Simultaneously the real part of the refractive index in the smoke layer increased to mR ≈ 1.5. The retrievals demonstrate also that the fine mode is predominant in the particle size distribution, and that the decrease of the effective radius with height is due to a shift of the fine mode toward smaller radii.
Highlights
Biomass burning (BB) is one of the key sources of aerosol emission
The general problem of passive sensors is that the results are appropriate for the particle column properties; the separate contributions of smoke layers, which may be above the planetary boundary layer (PBL), and aerosols within the PBL cannot be separated in a straightforward way
Instrument: the measurements were performed with the multi-wavelength Mie–Raman lidar at NASA Goddard Space Flight Center (GSFC)
Summary
Biomass burning (BB) is one of the key sources of aerosol emission. During large forest fires particles can be injected into the upper troposphere and transported over long distances affecting air quality in the subsidence regions. Multi-wavelength Raman lidar retrievals of BB aerosol have already been presented by several groups for smoke of tropical, North American and Russian origin (e.g., Müller et al, 2005, 2007a; Ansmann et al, 2009; Tesche et al, 2009; Amiridis et al, 2011; Murayama et al, 2004; Baars et al, 2012; Nicolae et al, 2013). These measurements have shown that the characteristics of aged smoke particles and their vertical distribution are highly variable, even when particles of the same origin are considered. The second (coming) part of this study, briefly summarized should give a complex event characterization combining analysis of aerosol retrievals from MODIS with aerosol source attribution from back trajectories and the Goddard Chemistry, Aerosol, Radiation and Transport module in a global Earth system model framework (GEOS-5 GOCART) (Bian et al, 2013; Chin et al, 2002, 2014; Colarco et al, 2010)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call