AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Measured Absorption Spectra of Aerosolized Carbonaceous Species and Their Influence on Climate Forcing
CHRISTOPHER ZANGMEISTER, James Radney, Rian You, Michael Zachariah, National Institute of Standards and Technology
Abstract Number: 312 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Understanding the impact of aerosol climate forcing requires quantitative measured of aerosol optical properties across a broad wavelength range. We present measured mass specific aerosol absorption spectra from elemental carbon allotropes, carbon black, flame generated soots, and brown carbon (BrC) from smoldering biomass generated from six species of North American wood. Data were measured between 500 nm and 840 nm and reported as mass specific absorption cross section (MAC) for each sample. The wavelength dependencies were determined using the absorption Ångström exponent (AAE). AAE were independent of measured MAC. The data indicate that carbonaceous aerosol absorption are highly dependent on sp2 bonding but independent of morphology. Particles generated from flames have morphology consistent with black carbon (BC) and the measured MAC was dependent on fuel and formation conditions. The MAC from flame generated particles varied between 3.8 m2 g-1 and 8.6 m2 g-1 at λ = 550 nm. Particles generated from smoldering biomass had AAEs between 3.5 and 6.2 with measured MAC from 0.014 m2 g-1 to 0.079 m2 g-1 at λ = 550 nm, nearly 2 orders of magnitude lower than flame generated soot. The results illustrate that to properly quantify carbonaceous aerosol absorption and to assess the impact of BC radiative forcing requires the measurement of aerosol with known mass across a broad spectral window.