AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Modeling of Regional Age Distribution of Black Carbon
HONGLIANG ZHANG, Qi Ying, Michael Kleeman, Texas A&M University
Abstract Number: 334 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Black carbon (BC) containing particles in the atmosphere, emitted from incomplete combustion of fuels, coal and biomass, have significantly affect air quality and climate because of their ability to absorb/reflect solar radiation and to affect cloud formation. To evaluate the impacts of BC on regional and global scales it is necessary to have accurate descriptions of the mixing status of BC particles and their spatial and temporal evolutions.
In this study, the source-oriented externally mixed 3D CIT/UCD model is enhanced to represent the age distribution of particles so that it is not only possible to determine the temporal and spatial variations of the particles and their source-origins but also their “aging” status (chemical compositions, optical properties). The source and age resolved 3D CIT/UCD model is applied to study the age distribution of BC in Southeast Texas. The model correctly predicts the overall concentrations of BC when compared to a base case simulation without age-resolved particle representation. Age-resolved simulation suggests that BC emitted within 0-3 hours contribute approximately 70-90% in urban Houston and about 20-40% in rural areas. Significant diurnal variations in the relative contributions to BC are predicted by the model. Highest contributions of fresh particles occur at morning and early evening traffic hours due to increased emission and lower mixing. The high level of fresh BC in the Southeast Texas area means that they could have a strong regional impact on aerosol optical and hygroscopic properties, and thus affect cloud formation and radiation balance.