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Combining Multi-Wavelength AERONET SSA Retrievals with a MIE Model to Quantify the Size of Absorbing Aerosols and the In-Situ Lifetime of Sulfate
  • Xinying Wang,
  • Jason Blake Cohen,
  • Shuo Wang
Xinying Wang
Sun Yat-sen University
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Jason Blake Cohen
School of Environment Science and Spatial Informatics, China University of Mining and Technology

Corresponding Author:jasonbc@alum.mit.edu

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Shuo Wang
Chengdu University of Information Technology
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Energy, transport, urbanization and burning are responsible for changes in atmospheric BC. This work uses direct solar atmospheric column measurements of single scatter albedo [SSA] retrieved at multiple wavelengths from AERONET at 68 Asian sites over 17 years. A MIE model is solved across the wavelengths using a core-shell mixing approximation to invert the probabilistic BC, shell size, and UV SSA. Orthogonal patterns are obtained for urban, biomass burning [BB], and long-range transport [LRT] conditions, which are used to analyze and attribute source types of BC across the region. Large urban areas (thought to be dominated by urban BC) are observations during targeted times (shorter than seasonally) to yield significant contributions from non-urban BC. BB and LRT are observed to dominate Beijing and Hong Kong 2 months a year. LRT is observed during the clean Asian Monsoon season in both Nepal and Hong Kong, with sources identified from thousands of kilometers away. Computing the shift in shell size required to constrain the results approximates secondary aerosol growth in-situ, and subsequently aerosol lifetime, which is found to range from 11 days to a month, implying both a significant amount of BC above the boundary layer, and that BC generally has a longer lifetime than PM2.5. These findings are outside of the range of most modeling studies focusing on PM2.5, but are consistent with independent measurements from SP2 and modeling studies of BC that use core-shell mixing together with high BC emissions.