Optical properties of light absorbing carbon aggregates mixed with sulfate: assessment of different model geometries for climate forcing calculations
Journal article, 2012
Light scattering by light absorbing carbon (LAC) aggregates encapsulated into sulfate shells is computed by use of the discrete dipole method. Computations are performed for a UV, visible, and IR wavelength, different particle sizes, and volume fractions. Reference computations are compared to three classes of simplified model particles that have been proposed for climate modeling purposes. Neither model matches the reference results sufficiently well. Remarkably, more realistic core-shell geometries fall behind homogeneous mixture models. An extended model based on a core-shell-shell geometry is proposed and tested. Good agreement is found for total optical cross sections and the asymmetry parameter.
soot
proceedings of the royal society of london series a-mathematical physical
spheres
absorption cross-sections
aerosol-particles
t-matrix
1990
algorithms
wavelength
ang h
radiative properties
black carbon
electromagnetic scattering
Author
Michael Kahnert
Chalmers, Earth and Space Sciences, Global Environmental Measurements and Modelling
T. Nousiainen
University of Helsinki
H. Lindqvist
University of Helsinki
M. Ebert
Technische Universität Darmstadt
Optics Express
1094-4087 (ISSN) 10944087 (eISSN)
Vol. 20 9 10042-10058Aerosol Optics in Global Earth System Modelling (AGES)
Swedish Research Council (VR) (2011-3346), 2011-10-26 -- 2014-10-26.
Subject Categories
Meteorology and Atmospheric Sciences
DOI
10.1364/OE.20.010042