Abstract View
Tracking the Evolution in Soot Aggregate Optical Properties Concurrently with its Morphology
OGOCHUKWU ENEKWIZU, Divjyot Singh, Alexei Khalizov, New Jersey Institute of Technology
Abstract Number: 154
Working Group: Carbonaceous Aerosol
Abstract
Radiative forcing by soot is strongly dependent on particle morphology and mixing state, which are complex and subject to significant change during atmospheric aging. The constantly evolving nature of soot is often overlooked in atmospheric models, resulting in significant uncertainties in their estimates of regional air quality and global climate. Our previous research has shown that fractal soot aggregates can restructure in the presence of particularly thin coatings. Recently, we developed an algorithm to model aggregate restructuring and found that individual aggregates with the same initial fractal parameters can end up with different levels of compactness. In this study, we examine the impact of structural evolution on the optical properties of thinly coated soot. We apply our restructuring algorithm to an ensemble of fractal aggregates with the same initial morphological parameters. As each aggregate restructures continuously from fractal to compact shape, we extract and save morphologies that match a set of predefined fractal parameters. Using Discrete Dipole Approximation (DDA), we compare the optical properties of our aggregates that were generated fractal and then restructured against those of aggregates that were generated compact. Additionally, we perform optical calculations on those fractal and compact aggregates after adding the coating material, which can be distributed in two different ways: a uniform layer or menisci localized in junctions between individual graphitic spheres in the aggregate. By tracking the evolution in optical properties of coated soot aggregates, the outcome of our findings will help improve the accuracy of radiative forcing by soot in atmospheric models.