HR: 09:18h
AN: A31C-04    [Abstracts]
TI: A study of radiative properties of fractal soot aggregates using the superposition T-matrix method
AU: * Liu, L
EM: lliu@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AU: Mishchenko, M I
EM: crmim@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AB: We employ the numerically exact superposition T-matrix method to perform extensive computations of scattering and absorption properties of soot aggregates with different compactness and size. The fractal dimension is used to quantify the mass dispersion of the particles. The optical properties of soot aggregates versus fractal dimension are a complex function of the refractive index of the material, the number of monomers, and the monomer radius a. It is shown that for a smaller a, when the fractal dimension is smaller than 2, the absorption cross section tends to be a constant, but increases rapidly when the fractal dimension is greater than 2. With a sufficient number of monomers and sufficiently large complex refractive index and monomer size, a reduction of light absorption is observed as the fractal dimension increases. The scattering cross section, on the other hand, increases monotonously as fractals evolve from chain-like to more densely packed ones, which is a strong manifestation of the importance of multiple scattering.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 0619 Electromagnetic theory
DE: 0669 Scattering and diffraction
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting