Numerical investigation on the Ångström exponent of black carbon aerosol

摘要: Black carbon (BC) plays an important role on the global and regional climate, whereas there are significant uncertainties its optical properties. Among various properties, Angstrom exponent (AE) indicates spectral variation of particle-optic interaction is widely used to understand aerosol We consider influence BC geometry properties assess sensitivity AE particle size distribution. The fractal aggregates with different dimensions represent realistic particles, popular equivalent volume spherical spheroidal models also considered for comparison. Even if become highly compact spherical, their still significantly from those spheres or spheroids. Meanwhile, Rayleigh-Debye-Gans approximation can hardly provide accurate results all quantities dimensions. extinction (EAE) absorption (AAE) sensitive both With becoming more (from aggregate spheroid sphere), becomes EAE AAE distributions vary between 1.10–1.63 0.87–1.50, respectively, spheroids have wider ranges. Furthermore, at smaller wavelengths (between 0.35 µm 0.55 µm) distribution than that given by larger 0.55 µm 0.88 µm).