A new method to study variation of aerosol optical properties using 3-D reconstructions

摘要

3-D reconstruction of ambient particles was possible through the use of the FIB-SEM technique and visualization software. It included particle's inherent voids and inclusions whether they were light-absorbing or light-scattering phases. Absorption and scattering behavior of select 3-D reconstructions was resolved using DDA optical property model and compared to Mie scattering theory. DDA captured the complexities in particle morphology that other models like the Mie theory do not. Efficiencies in scattering, extinction, absorption and backscattering were evaluated in this study. Preliminary results indicate that the shape of the particle was the dominating factor affecting the variation of optical properties and that backscattering efficiency was the most sensitive to differences in shape. These results suggest that assigning ambient particles as spheres in climate models could result in large errors in predicting radiative forcing. The use of FIB-SEM data to reconstruct the 3-D composition of individual particles creates an innovative and more realistic way to reproduce irregularly shaped ambient particles and study their optical properties using models like DDA.